diff --git a/ruma-events/CHANGELOG.md b/ruma-events/CHANGELOG.md
index a561e4f6..9fbf17dc 100644
--- a/ruma-events/CHANGELOG.md
+++ b/ruma-events/CHANGELOG.md
@@ -10,6 +10,7 @@ Breaking changes:
   struct variants
   * This change removes the types `EventMatchCondition`, `RoomMemberCountCondition` and
     `SenderNotificationPermissionCondition`
+* Add PDU types: `pdu::{Pdu, PduStub}`
 
 Improvements:
 
diff --git a/ruma-events/src/lib.rs b/ruma-events/src/lib.rs
index 2b87bad2..91810ed7 100644
--- a/ruma-events/src/lib.rs
+++ b/ruma-events/src/lib.rs
@@ -147,6 +147,7 @@ pub mod forwarded_room_key;
 pub mod fully_read;
 pub mod ignored_user_list;
 pub mod key;
+pub mod pdu;
 pub mod presence;
 pub mod push_rules;
 pub mod receipt;
diff --git a/ruma-events/src/pdu.rs b/ruma-events/src/pdu.rs
new file mode 100644
index 00000000..75aad814
--- /dev/null
+++ b/ruma-events/src/pdu.rs
@@ -0,0 +1,325 @@
+//! Types for persistent data unit schemas
+//!
+//! The differences between the `RoomV1Pdu` schema and the `RoomV3Pdu` schema are
+//! that the `RoomV1Pdu` takes an `event_id` field (`RoomV3Pdu` does not), and
+//! `auth_events` and `prev_events` take `Vec<(EventId, EventHash)> rather than
+//! `Vec<EventId>` in `RoomV3Pdu`.
+//!
+//! The stubbed versions of each PDU type remove the `event_id` field (if any)
+//! and the `room_id` field for use in PDU templates.
+
+use std::{collections::BTreeMap, time::SystemTime};
+
+use js_int::UInt;
+use ruma_events::EventType;
+use ruma_identifiers::{EventId, RoomId, UserId};
+use serde::{Deserialize, Serialize};
+use serde_json::Value as JsonValue;
+
+/// Enum for PDU schemas
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(untagged)]
+pub enum Pdu {
+    /// PDU for room versions 1 and 2.
+    RoomV1Pdu(RoomV1Pdu),
+    /// PDU for room versions 3 and above.
+    RoomV3Pdu(RoomV3Pdu),
+}
+
+/// A 'persistent data unit' (event) for room versions 1 and 2.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct RoomV1Pdu {
+    /// Event ID for the PDU.
+    pub event_id: EventId,
+
+    /// The room this event belongs to.
+    pub room_id: RoomId,
+
+    /// The user id of the user who sent this event.
+    pub sender: UserId,
+
+    /// The `server_name` of the homeserver that created this event.
+    pub origin: String,
+
+    /// Timestamp (milliseconds since the UNIX epoch) on originating homeserver
+    /// of when this event was created.
+    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
+    pub origin_server_ts: SystemTime,
+
+    // TODO: Encode event type as content enum variant, like event enums do
+    /// The event's type.
+    #[serde(rename = "type")]
+    pub kind: EventType,
+
+    /// The event's content.
+    pub content: JsonValue,
+
+    /// A key that determines which piece of room state the event represents.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub state_key: Option<String>,
+
+    /// Event IDs for the most recent events in the room that the homeserver was
+    /// aware of when it created this event.
+    #[serde(skip_serializing_if = "Vec::is_empty")]
+    pub prev_events: Vec<(EventId, EventHash)>,
+
+    /// The maximum depth of the `prev_events`, plus one.
+    pub depth: UInt,
+
+    /// Event IDs for the authorization events that would allow this event to be
+    /// in the room.
+    #[serde(skip_serializing_if = "Vec::is_empty")]
+    pub auth_events: Vec<(EventId, EventHash)>,
+
+    /// For redaction events, the ID of the event being redacted.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub redacts: Option<EventId>,
+
+    /// Additional data added by the origin server but not covered by the
+    /// signatures.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, JsonValue>,
+
+    /// Content hashes of the PDU.
+    pub hashes: EventHash,
+
+    /// Signatures for the PDU.
+    pub signatures: BTreeMap<String, BTreeMap<String, String>>,
+}
+
+/// A 'persistent data unit' (event) for room versions 3 and beyond.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct RoomV3Pdu {
+    /// The room this event belongs to.
+    pub room_id: RoomId,
+
+    /// The user id of the user who sent this event.
+    pub sender: UserId,
+
+    /// The `server_name` of the homeserver that created this event.
+    pub origin: String,
+
+    /// Timestamp (milliseconds since the UNIX epoch) on originating homeserver
+    /// of when this event was created.
+    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
+    pub origin_server_ts: SystemTime,
+
+    // TODO: Encode event type as content enum variant, like event enums do
+    /// The event's type.
+    #[serde(rename = "type")]
+    pub kind: EventType,
+
+    /// The event's content.
+    pub content: JsonValue,
+
+    /// A key that determines which piece of room state the event represents.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub state_key: Option<String>,
+
+    /// Event IDs for the most recent events in the room that the homeserver was
+    /// aware of when it created this event.
+    pub prev_events: Vec<EventId>,
+
+    /// The maximum depth of the `prev_events`, plus one.
+    pub depth: UInt,
+
+    /// Event IDs for the authorization events that would allow this event to be
+    /// in the room.
+    pub auth_events: Vec<EventId>,
+
+    /// For redaction events, the ID of the event being redacted.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub redacts: Option<EventId>,
+
+    /// Additional data added by the origin server but not covered by the
+    /// signatures.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, JsonValue>,
+
+    /// Content hashes of the PDU.
+    pub hashes: EventHash,
+
+    /// Signatures for the PDU.
+    pub signatures: BTreeMap<String, BTreeMap<String, String>>,
+}
+
+/// PDU type without event and room IDs.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(untagged)]
+pub enum PduStub {
+    /// Stub for PDUs of room version 1 and 2.
+    RoomV1PduStub(RoomV1PduStub),
+
+    /// Stub for PDUs of room versions 3 and above.
+    RoomV3PduStub(RoomV3PduStub),
+}
+
+impl PduStub {
+    /// Helper method to get PDU from a PDU stub.
+    pub fn into_pdu(self, room_id: RoomId, event_id: EventId) -> Pdu {
+        match self {
+            PduStub::RoomV1PduStub(v1_stub) => {
+                Pdu::RoomV1Pdu(v1_stub.into_v1_pdu(room_id, event_id))
+            }
+            PduStub::RoomV3PduStub(v3_stub) => Pdu::RoomV3Pdu(v3_stub.into_v3_pdu(room_id)),
+        }
+    }
+}
+
+/// Stub for PDUs of room version 1 and 2.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct RoomV1PduStub {
+    /// The user id of the user who sent this event.
+    pub sender: UserId,
+
+    /// The `server_name` of the homeserver that created this event.
+    pub origin: String,
+
+    /// Timestamp (milliseconds since the UNIX epoch) on originating homeserver
+    /// of when this event was created.
+    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
+    pub origin_server_ts: SystemTime,
+
+    // TODO: Encode event type as content enum variant, like event enums do
+    /// The event's type.
+    #[serde(rename = "type")]
+    pub kind: EventType,
+
+    /// The event's content.
+    pub content: JsonValue,
+
+    /// A key that determines which piece of room state the event represents.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub state_key: Option<String>,
+
+    /// Event IDs for the most recent events in the room that the homeserver was
+    /// aware of when it created this event.
+    pub prev_events: Vec<(EventId, EventHash)>,
+
+    /// The maximum depth of the `prev_events`, plus one.
+    pub depth: UInt,
+
+    /// Event IDs for the authorization events that would allow this event to be
+    /// in the room.
+    pub auth_events: Vec<(EventId, EventHash)>,
+
+    /// For redaction events, the ID of the event being redacted.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub redacts: Option<EventId>,
+
+    /// Additional data added by the origin server but not covered by the
+    /// signatures.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, JsonValue>,
+
+    /// Content hashes of the PDU.
+    pub hashes: EventHash,
+
+    /// Signatures for the PDU.
+    pub signatures: BTreeMap<String, BTreeMap<String, String>>,
+}
+
+impl RoomV1PduStub {
+    /// Converts a V1 PDU stub into a full V1 PDU.
+    pub fn into_v1_pdu(self, room_id: RoomId, event_id: EventId) -> RoomV1Pdu {
+        RoomV1Pdu {
+            event_id,
+            room_id,
+            sender: self.sender,
+            origin: self.origin,
+            origin_server_ts: self.origin_server_ts,
+            kind: self.kind,
+            content: self.content,
+            state_key: self.state_key,
+            prev_events: self.prev_events,
+            depth: self.depth,
+            auth_events: self.auth_events,
+            redacts: self.redacts,
+            unsigned: self.unsigned,
+            hashes: self.hashes,
+            signatures: self.signatures,
+        }
+    }
+}
+
+/// Stub for PDUs of room versions 3 and above.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct RoomV3PduStub {
+    /// The user id of the user who sent this event.
+    pub sender: UserId,
+
+    /// The `server_name` of the homeserver that created this event.
+    pub origin: String,
+
+    /// Timestamp (milliseconds since the UNIX epoch) on originating homeserver
+    /// of when this event was created.
+    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
+    pub origin_server_ts: SystemTime,
+
+    // TODO: Encode event type as content enum variant, like event enums do
+    /// The event's type.
+    #[serde(rename = "type")]
+    pub kind: EventType,
+
+    /// The event's content.
+    pub content: JsonValue,
+
+    /// A key that determines which piece of room state the event represents.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub state_key: Option<String>,
+
+    /// Event IDs for the most recent events in the room that the homeserver was
+    /// aware of when it created this event.
+    pub prev_events: Vec<EventId>,
+
+    /// The maximum depth of the `prev_events`, plus one.
+    pub depth: UInt,
+
+    /// Event IDs for the authorization events that would allow this event to be
+    /// in the room.
+    pub auth_events: Vec<EventId>,
+
+    /// For redaction events, the ID of the event being redacted.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub redacts: Option<EventId>,
+
+    /// Additional data added by the origin server but not covered by the
+    /// signatures.
+    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
+    pub unsigned: BTreeMap<String, JsonValue>,
+
+    /// Content hashes of the PDU.
+    pub hashes: EventHash,
+
+    /// Signatures for the PDU.
+    pub signatures: BTreeMap<String, BTreeMap<String, String>>,
+}
+
+impl RoomV3PduStub {
+    /// Converts a V3 PDU stub into a full V3 PDU.
+    pub fn into_v3_pdu(self, room_id: RoomId) -> RoomV3Pdu {
+        RoomV3Pdu {
+            room_id,
+            sender: self.sender,
+            origin: self.origin,
+            origin_server_ts: self.origin_server_ts,
+            kind: self.kind,
+            content: self.content,
+            state_key: self.state_key,
+            prev_events: self.prev_events,
+            depth: self.depth,
+            auth_events: self.auth_events,
+            redacts: self.redacts,
+            unsigned: self.unsigned,
+            hashes: self.hashes,
+            signatures: self.signatures,
+        }
+    }
+}
+
+/// Content hashes of a PDU.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct EventHash {
+    /// The SHA-256 hash.
+    pub sha256: String,
+}
diff --git a/ruma-events/tests/pdu.rs b/ruma-events/tests/pdu.rs
new file mode 100644
index 00000000..508c3de3
--- /dev/null
+++ b/ruma-events/tests/pdu.rs
@@ -0,0 +1,605 @@
+use std::{
+    collections::BTreeMap,
+    convert::TryFrom,
+    time::{Duration, SystemTime},
+};
+
+use matches::assert_matches;
+use ruma_events::{
+    pdu::{EventHash, Pdu, PduStub, RoomV1Pdu, RoomV1PduStub, RoomV3Pdu, RoomV3PduStub},
+    EventType,
+};
+use ruma_identifiers::{EventId, RoomId, UserId};
+use serde_json::{from_value as from_json_value, json, to_value as to_json_value};
+
+#[test]
+fn serialize_stub_as_v1() {
+    let mut signatures = BTreeMap::new();
+    let mut inner_signature = BTreeMap::new();
+    inner_signature.insert(
+        "ed25519:key_version".to_string(),
+        "86BytesOfSignatureOfTheRedactedEvent".to_string(),
+    );
+    signatures.insert("example.com".to_string(), inner_signature);
+
+    let mut unsigned = BTreeMap::new();
+    unsigned.insert("somekey".to_string(), json!({"a": 456}));
+
+    let v1_stub = RoomV1PduStub {
+        sender: UserId::try_from("@sender:example.com").unwrap(),
+        origin: "matrix.org".to_string(),
+        origin_server_ts: SystemTime::UNIX_EPOCH + Duration::from_millis(1_592_050_773_658),
+        kind: EventType::RoomPowerLevels,
+        content: json!({"testing": 123}),
+        state_key: Some("state".to_string()),
+        prev_events: vec![(
+            EventId::try_from("$previousevent:matrix.org").unwrap(),
+            EventHash { sha256: "123567".to_string() },
+        )],
+        depth: 2_u32.into(),
+        auth_events: vec![(
+            EventId::try_from("$someauthevent:matrix.org").unwrap(),
+            EventHash { sha256: "21389CFEDABC".to_string() },
+        )],
+        redacts: Some(EventId::try_from("$9654:matrix.org").unwrap()),
+        unsigned,
+        hashes: EventHash { sha256: "1233543bABACDEF".to_string() },
+        signatures,
+    };
+    let pdu_stub = PduStub::RoomV1PduStub(v1_stub);
+    let json = json!({
+        "sender": "@sender:example.com",
+        "origin": "matrix.org",
+        "origin_server_ts": 1_592_050_773_658 as usize,
+        "type": "m.room.power_levels",
+        "content": {
+            "testing": 123
+        },
+        "state_key": "state",
+        "prev_events": [
+            [ "$previousevent:matrix.org", {"sha256": "123567"} ]
+        ],
+        "depth": 2,
+        "auth_events": [
+            ["$someauthevent:matrix.org", {"sha256": "21389CFEDABC"}]
+        ],
+        "redacts": "$9654:matrix.org",
+        "unsigned": {
+            "somekey": { "a": 456 } },
+        "hashes": { "sha256": "1233543bABACDEF" },
+        "signatures": {
+            "example.com": { "ed25519:key_version":"86BytesOfSignatureOfTheRedactedEvent" }
+        }
+    });
+
+    assert_eq!(to_json_value(&pdu_stub).unwrap(), json);
+}
+
+#[test]
+fn serialize_stub_as_v3() {
+    let mut signatures = BTreeMap::new();
+    let mut inner_signature = BTreeMap::new();
+    inner_signature.insert(
+        "ed25519:key_version".to_string(),
+        "86BytesOfSignatureOfTheRedactedEvent".to_string(),
+    );
+    signatures.insert("example.com".to_string(), inner_signature);
+
+    let mut unsigned = BTreeMap::new();
+    unsigned.insert("somekey".to_string(), json!({"a": 456}));
+
+    let v3_stub = RoomV3PduStub {
+        sender: UserId::try_from("@sender:example.com").unwrap(),
+        origin: "matrix.org".to_string(),
+        origin_server_ts: SystemTime::UNIX_EPOCH + Duration::from_millis(1_592_050_773_658),
+        kind: EventType::RoomPowerLevels,
+        content: json!({"testing": 123}),
+        state_key: Some("state".to_string()),
+        prev_events: vec![EventId::try_from("$previousevent:matrix.org").unwrap()],
+        depth: 2_u32.into(),
+        auth_events: vec![EventId::try_from("$someauthevent:matrix.org").unwrap()],
+        redacts: Some(EventId::try_from("$9654:matrix.org").unwrap()),
+        unsigned,
+        hashes: EventHash { sha256: "1233543bABACDEF".to_string() },
+        signatures,
+    };
+    let pdu_stub = PduStub::RoomV3PduStub(v3_stub);
+    let json = json!({
+        "sender": "@sender:example.com",
+        "origin": "matrix.org",
+        "origin_server_ts": 1_592_050_773_658 as usize,
+        "type": "m.room.power_levels",
+        "content": {
+            "testing": 123
+        },
+        "state_key": "state",
+        "prev_events": [ "$previousevent:matrix.org" ],
+        "depth": 2,
+        "auth_events": ["$someauthevent:matrix.org" ],
+        "redacts": "$9654:matrix.org",
+        "unsigned": {
+            "somekey": { "a": 456 } },
+        "hashes": { "sha256": "1233543bABACDEF" },
+        "signatures": {
+            "example.com": { "ed25519:key_version":"86BytesOfSignatureOfTheRedactedEvent" }
+        }
+    });
+
+    assert_eq!(to_json_value(&pdu_stub).unwrap(), json);
+}
+
+#[test]
+fn test_deserialize_stub_as_v1() {
+    let json = json!({
+        "auth_events": [
+            [
+                "$abc123:matrix.org",
+                {
+                    "sha256": "Base64EncodedSha256HashesShouldBe43BytesLong"
+                }
+            ]
+        ],
+        "content": {
+            "key": "value"
+        },
+        "depth": 12,
+        "event_id": "$a4ecee13e2accdadf56c1025:example.com",
+        "hashes": {
+            "sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
+        },
+        "origin": "matrix.org",
+        "origin_server_ts": 1_234_567_890,
+        "prev_events": [
+            [
+                "$abc123:matrix.org",
+                {
+                    "sha256": "Base64EncodedSha256HashesShouldBe43BytesLong"
+                }
+            ]
+        ],
+        "redacts": "$def456:matrix.org",
+        "room_id": "!abc123:matrix.org",
+        "sender": "@someone:matrix.org",
+        "signatures": {
+            "example.com": {
+                "ed25519:key_version:": "86BytesOfSignatureOfTheRedactedEvent"
+            }
+        },
+        "state_key": "my_key",
+        "type": "m.room.message",
+        "unsigned": {
+            "key": "value"
+        }
+    });
+    let parsed = from_json_value::<PduStub>(json).unwrap();
+
+    match parsed {
+        PduStub::RoomV1PduStub(v1_stub) => {
+            assert_eq!(
+                v1_stub.auth_events.first().unwrap().0,
+                EventId::try_from("$abc123:matrix.org").unwrap()
+            );
+            assert_eq!(
+                v1_stub.auth_events.first().unwrap().1.sha256,
+                "Base64EncodedSha256HashesShouldBe43BytesLong"
+            );
+        }
+        PduStub::RoomV3PduStub(_) => panic!("Matched V3 stub"),
+    }
+}
+
+#[test]
+fn deserialize_stub_as_v3() {
+    let json = json!({
+        "auth_events": [
+            "$abc123:matrix.org"
+        ],
+        "content": {
+            "key": "value"
+        },
+        "depth": 12,
+        "event_id": "$a4ecee13e2accdadf56c1025:example.com",
+        "hashes": {
+            "sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
+        },
+        "origin": "matrix.org",
+        "origin_server_ts": 1_234_567_890,
+        "prev_events": [
+                "$abc123:matrix.org"
+        ],
+        "redacts": "$def456:matrix.org",
+        "room_id": "!abc123:matrix.org",
+        "sender": "@someone:matrix.org",
+        "signatures": {
+            "example.com": {
+                "ed25519:key_version:": "86BytesOfSignatureOfTheRedactedEvent"
+            }
+        },
+        "state_key": "my_key",
+        "type": "m.room.message",
+        "unsigned": {
+            "key": "value"
+        }
+    });
+    let parsed = from_json_value::<PduStub>(json).unwrap();
+
+    match parsed {
+        PduStub::RoomV1PduStub(_) => panic!("Matched V1 stub"),
+        PduStub::RoomV3PduStub(v3_stub) => {
+            assert_eq!(
+                v3_stub.auth_events.first().unwrap(),
+                &EventId::try_from("$abc123:matrix.org").unwrap()
+            );
+        }
+    }
+}
+
+#[test]
+fn serialize_pdu_as_v1() {
+    let mut signatures = BTreeMap::new();
+    let mut inner_signature = BTreeMap::new();
+    inner_signature.insert(
+        "ed25519:key_version".to_string(),
+        "86BytesOfSignatureOfTheRedactedEvent".to_string(),
+    );
+    signatures.insert("example.com".to_string(), inner_signature);
+
+    let mut unsigned = BTreeMap::new();
+    unsigned.insert("somekey".to_string(), json!({"a": 456}));
+
+    let v1_pdu = RoomV1Pdu {
+        room_id: RoomId::try_from("!n8f893n9:example.com").unwrap(),
+        event_id: EventId::try_from("$somejoinevent:matrix.org").unwrap(),
+        sender: UserId::try_from("@sender:example.com").unwrap(),
+        origin: "matrix.org".to_string(),
+        origin_server_ts: SystemTime::UNIX_EPOCH + Duration::from_millis(1_592_050_773_658),
+        kind: EventType::RoomPowerLevels,
+        content: json!({"testing": 123}),
+        state_key: Some("state".to_string()),
+        prev_events: vec![(
+            EventId::try_from("$previousevent:matrix.org").unwrap(),
+            EventHash { sha256: "123567".to_string() },
+        )],
+        depth: 2_u32.into(),
+        auth_events: vec![(
+            EventId::try_from("$someauthevent:matrix.org").unwrap(),
+            EventHash { sha256: "21389CFEDABC".to_string() },
+        )],
+        redacts: Some(EventId::try_from("$9654:matrix.org").unwrap()),
+        unsigned,
+        hashes: EventHash { sha256: "1233543bABACDEF".to_string() },
+        signatures,
+    };
+    let pdu = Pdu::RoomV1Pdu(v1_pdu);
+    let json = json!({
+        "room_id": "!n8f893n9:example.com",
+        "event_id": "$somejoinevent:matrix.org",
+        "sender": "@sender:example.com",
+        "origin": "matrix.org",
+        "origin_server_ts": 1_592_050_773_658 as usize,
+        "type": "m.room.power_levels",
+        "content": {
+            "testing": 123
+        },
+        "state_key": "state",
+        "prev_events": [
+            [ "$previousevent:matrix.org", {"sha256": "123567"} ]
+        ],
+        "depth": 2,
+        "auth_events": [
+            ["$someauthevent:matrix.org", {"sha256": "21389CFEDABC"}]
+        ],
+        "redacts": "$9654:matrix.org",
+        "unsigned": {
+            "somekey": { "a": 456 } },
+        "hashes": { "sha256": "1233543bABACDEF" },
+        "signatures": {
+            "example.com": { "ed25519:key_version":"86BytesOfSignatureOfTheRedactedEvent" }
+        }
+    });
+
+    assert_eq!(to_json_value(&pdu).unwrap(), json);
+}
+
+#[test]
+fn serialize_pdu_as_v3() {
+    let mut signatures = BTreeMap::new();
+    let mut inner_signature = BTreeMap::new();
+    inner_signature.insert(
+        "ed25519:key_version".to_string(),
+        "86BytesOfSignatureOfTheRedactedEvent".to_string(),
+    );
+    signatures.insert("example.com".to_string(), inner_signature);
+
+    let mut unsigned = BTreeMap::new();
+    unsigned.insert("somekey".to_string(), json!({"a": 456}));
+
+    let v3_pdu = RoomV3Pdu {
+        room_id: RoomId::try_from("!n8f893n9:example.com").unwrap(),
+        sender: UserId::try_from("@sender:example.com").unwrap(),
+        origin: "matrix.org".to_string(),
+        origin_server_ts: SystemTime::UNIX_EPOCH + Duration::from_millis(1_592_050_773_658),
+        kind: EventType::RoomPowerLevels,
+        content: json!({"testing": 123}),
+        state_key: Some("state".to_string()),
+        prev_events: vec![EventId::try_from("$previousevent:matrix.org").unwrap()],
+        depth: 2_u32.into(),
+        auth_events: vec![EventId::try_from("$someauthevent:matrix.org").unwrap()],
+        redacts: Some(EventId::try_from("$9654:matrix.org").unwrap()),
+        unsigned,
+        hashes: EventHash { sha256: "1233543bABACDEF".to_string() },
+        signatures,
+    };
+    let pdu_stub = Pdu::RoomV3Pdu(v3_pdu);
+    let json = json!({
+        "room_id": "!n8f893n9:example.com",
+        "sender": "@sender:example.com",
+        "origin": "matrix.org",
+        "origin_server_ts": 1_592_050_773_658 as usize,
+        "type": "m.room.power_levels",
+        "content": {
+            "testing": 123
+        },
+        "state_key": "state",
+        "prev_events": [ "$previousevent:matrix.org" ],
+        "depth": 2,
+        "auth_events": ["$someauthevent:matrix.org" ],
+        "redacts": "$9654:matrix.org",
+        "unsigned": {
+            "somekey": { "a": 456 } },
+        "hashes": { "sha256": "1233543bABACDEF" },
+        "signatures": {
+            "example.com": { "ed25519:key_version":"86BytesOfSignatureOfTheRedactedEvent" }
+        }
+    });
+
+    assert_eq!(to_json_value(&pdu_stub).unwrap(), json);
+}
+
+#[test]
+fn test_deserialize_pdu_as_v1() {
+    let json = json!({
+        "room_id": "!n8f893n9:example.com",
+        "event_id": "$somejoinevent:matrix.org",
+        "auth_events": [
+            [
+                "$abc123:matrix.org",
+                {
+                    "sha256": "Base64EncodedSha256HashesShouldBe43BytesLong"
+                }
+            ]
+        ],
+        "content": {
+            "key": "value"
+        },
+        "depth": 12,
+        "event_id": "$a4ecee13e2accdadf56c1025:example.com",
+        "hashes": {
+            "sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
+        },
+        "origin": "matrix.org",
+        "origin_server_ts": 1_234_567_890,
+        "prev_events": [
+            [
+                "$abc123:matrix.org",
+                {
+                    "sha256": "Base64EncodedSha256HashesShouldBe43BytesLong"
+                }
+            ]
+        ],
+        "redacts": "$def456:matrix.org",
+        "room_id": "!abc123:matrix.org",
+        "sender": "@someone:matrix.org",
+        "signatures": {
+            "example.com": {
+                "ed25519:key_version:": "86BytesOfSignatureOfTheRedactedEvent"
+            }
+        },
+        "state_key": "my_key",
+        "type": "m.room.message",
+        "unsigned": {
+            "key": "value"
+        }
+    });
+    let parsed = from_json_value::<Pdu>(json).unwrap();
+
+    match parsed {
+        Pdu::RoomV1Pdu(v1_pdu) => {
+            assert_eq!(
+                v1_pdu.auth_events.first().unwrap().0,
+                EventId::try_from("$abc123:matrix.org").unwrap()
+            );
+            assert_eq!(
+                v1_pdu.auth_events.first().unwrap().1.sha256,
+                "Base64EncodedSha256HashesShouldBe43BytesLong"
+            );
+        }
+        Pdu::RoomV3Pdu(_) => panic!("Matched V3 PDU"),
+    }
+}
+
+#[test]
+fn deserialize_pdu_as_v3() {
+    let json = json!({
+        "room_id": "!n8f893n9:example.com",
+        "auth_events": [
+            "$abc123:matrix.org"
+        ],
+        "content": {
+            "key": "value"
+        },
+        "depth": 12,
+        "event_id": "$a4ecee13e2accdadf56c1025:example.com",
+        "hashes": {
+            "sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
+        },
+        "origin": "matrix.org",
+        "origin_server_ts": 1_234_567_890,
+        "prev_events": [
+                "$abc123:matrix.org"
+        ],
+        "redacts": "$def456:matrix.org",
+        "room_id": "!abc123:matrix.org",
+        "sender": "@someone:matrix.org",
+        "signatures": {
+            "example.com": {
+                "ed25519:key_version:": "86BytesOfSignatureOfTheRedactedEvent"
+            }
+        },
+        "state_key": "my_key",
+        "type": "m.room.message",
+        "unsigned": {
+            "key": "value"
+        }
+    });
+    let parsed = from_json_value::<Pdu>(json).unwrap();
+
+    match parsed {
+        Pdu::RoomV1Pdu(_) => panic!("Matched V1 PDU"),
+        Pdu::RoomV3Pdu(v3_pdu) => {
+            assert_eq!(
+                v3_pdu.auth_events.first().unwrap(),
+                &EventId::try_from("$abc123:matrix.org").unwrap()
+            );
+        }
+    }
+}
+
+#[test]
+fn convert_v1_stub_to_pdu() {
+    let mut signatures = BTreeMap::new();
+    let mut inner_signature = BTreeMap::new();
+    inner_signature.insert(
+        "ed25519:key_version".to_string(),
+        "86BytesOfSignatureOfTheRedactedEvent".to_string(),
+    );
+    signatures.insert("example.com".to_string(), inner_signature);
+
+    let mut unsigned = BTreeMap::new();
+    unsigned.insert("somekey".to_string(), json!({"a": 456}));
+
+    let v1_stub = RoomV1PduStub {
+        sender: UserId::try_from("@sender:example.com").unwrap(),
+        origin: "matrix.org".to_string(),
+        origin_server_ts: SystemTime::UNIX_EPOCH + Duration::from_millis(1_592_050_773_658),
+        kind: EventType::RoomPowerLevels,
+        content: json!({"testing": 123}),
+        state_key: Some("state".to_string()),
+        prev_events: vec![(
+            EventId::try_from("$previousevent:matrix.org").unwrap(),
+            EventHash { sha256: "123567".to_string() },
+        )],
+        depth: 2_u32.into(),
+        auth_events: vec![(
+            EventId::try_from("$someauthevent:matrix.org").unwrap(),
+            EventHash { sha256: "21389CFEDABC".to_string() },
+        )],
+        redacts: Some(EventId::try_from("$9654:matrix.org").unwrap()),
+        unsigned: (&unsigned).clone(),
+        hashes: EventHash { sha256: "1233543bABACDEF".to_string() },
+        signatures: (&signatures).clone(),
+    };
+
+    assert_matches!(
+        v1_stub.into_v1_pdu(
+            RoomId::try_from("!n8f893n9:example.com").unwrap(),
+            EventId::try_from("$somejoinevent:matrix.org").unwrap()
+        ),
+        RoomV1Pdu {
+            room_id,
+            event_id,
+            sender,
+            origin,
+            origin_server_ts,
+            kind,
+            content,
+            state_key,
+            prev_events,
+            depth,
+            auth_events,
+            redacts,
+            unsigned,
+            hashes: EventHash { sha256 },
+            signatures,
+        } if room_id == RoomId::try_from("!n8f893n9:example.com").unwrap()
+            && event_id == EventId::try_from("$somejoinevent:matrix.org").unwrap()
+            && sender == UserId::try_from("@sender:example.com").unwrap()
+            && origin == "matrix.org"
+            && origin_server_ts == SystemTime::UNIX_EPOCH + Duration::from_millis(1_592_050_773_658)
+            && kind == EventType::RoomPowerLevels
+            && content == json!({"testing": 123})
+            && state_key == Some("state".to_string())
+            && prev_events[0].0 == EventId::try_from("$previousevent:matrix.org").unwrap()
+            && prev_events[0].1.sha256 == "123567"
+            && depth == 2_u32.into()
+            && auth_events.first().unwrap().0 == EventId::try_from("$someauthevent:matrix.org").unwrap()
+            && auth_events.first().unwrap().1.sha256 == "21389CFEDABC"
+            && redacts == Some(EventId::try_from("$9654:matrix.org").unwrap())
+            && unsigned == (&unsigned).clone()
+            && sha256 == "1233543bABACDEF"
+            && signatures == (&signatures).clone()
+    );
+}
+
+#[test]
+fn convert_v3_stub_to_pdu() {
+    let mut signatures = BTreeMap::new();
+    let mut inner_signature = BTreeMap::new();
+    inner_signature.insert(
+        "ed25519:key_version".to_string(),
+        "86BytesOfSignatureOfTheRedactedEvent".to_string(),
+    );
+    signatures.insert("example.com".to_string(), inner_signature);
+
+    let mut unsigned = BTreeMap::new();
+    unsigned.insert("somekey".to_string(), json!({"a": 456}));
+
+    let v3_stub = RoomV3PduStub {
+        sender: UserId::try_from("@sender:example.com").unwrap(),
+        origin: "matrix.org".to_string(),
+        origin_server_ts: SystemTime::UNIX_EPOCH + Duration::from_millis(1_592_050_773_658),
+        kind: EventType::RoomPowerLevels,
+        content: json!({"testing": 123}),
+        state_key: Some("state".to_string()),
+        prev_events: vec![EventId::try_from("$previousevent:matrix.org").unwrap()],
+        depth: 2_u32.into(),
+        auth_events: vec![EventId::try_from("$someauthevent:matrix.org").unwrap()],
+        redacts: Some(EventId::try_from("$9654:matrix.org").unwrap()),
+        unsigned: (&unsigned).clone(),
+        hashes: EventHash { sha256: "1233543bABACDEF".to_string() },
+        signatures: (&signatures).clone(),
+    };
+
+    assert_matches!(
+        v3_stub.into_v3_pdu(RoomId::try_from("!n8f893n9:example.com").unwrap()),
+        RoomV3Pdu {
+            room_id,
+            sender,
+            origin,
+            origin_server_ts,
+            kind,
+            content,
+            state_key,
+            prev_events,
+            depth,
+            auth_events,
+            redacts,
+            unsigned,
+            hashes: EventHash { sha256 },
+            signatures,
+        } if room_id == RoomId::try_from("!n8f893n9:example.com").unwrap()
+            && sender == UserId::try_from("@sender:example.com").unwrap()
+            && origin == "matrix.org"
+            && origin_server_ts == SystemTime::UNIX_EPOCH + Duration::from_millis(1_592_050_773_658)
+            && kind == EventType::RoomPowerLevels
+            && content == json!({"testing": 123})
+            && state_key == Some("state".to_string())
+            && prev_events == vec![EventId::try_from("$previousevent:matrix.org").unwrap()]
+            && depth == 2_u32.into()
+            && auth_events == vec![EventId::try_from("$someauthevent:matrix.org").unwrap()]
+            && redacts == Some(EventId::try_from("$9654:matrix.org").unwrap())
+            && unsigned == (&unsigned).clone()
+            && sha256 == "1233543bABACDEF"
+            && signatures == (&signatures).clone()
+    );
+}
diff --git a/ruma-federation-api/CHANGELOG.md b/ruma-federation-api/CHANGELOG.md
index bed78bb5..581a742a 100644
--- a/ruma-federation-api/CHANGELOG.md
+++ b/ruma-federation-api/CHANGELOG.md
@@ -1,5 +1,9 @@
 # [unreleased]
 
+Breaking Changes:
+
+* Replace `RoomV3Pdu` with `ruma_events::pdu::{Pdu, PduStub}`.
+
 Improvements:
 
 * Add endpoints:
@@ -15,6 +19,7 @@ Improvements:
         create_join_event_template::v1
     },
     query::get_room_information::v1,
+    transactions::send_transaction_message::v1,
     version::get_server_version::v1
   ```
 
diff --git a/ruma-federation-api/src/lib.rs b/ruma-federation-api/src/lib.rs
index ef6a1c66..ef95d3f6 100644
--- a/ruma-federation-api/src/lib.rs
+++ b/ruma-federation-api/src/lib.rs
@@ -2,69 +2,10 @@
 
 #![warn(missing_docs)]
 
-use std::{collections::BTreeMap, time::SystemTime};
-
-use ::serde::{Deserialize, Serialize};
-use js_int::UInt;
-use ruma_events::EventType;
-use ruma_identifiers::{EventId, RoomId, UserId};
-use serde_json::Value as JsonValue;
-
 mod serde;
 
 pub mod directory;
 pub mod discovery;
 pub mod membership;
 pub mod query;
-
-/// A 'persistent data unit' (event) for room versions 3 and beyond.
-#[derive(Deserialize, Serialize)]
-pub struct RoomV3Pdu {
-    /// The room this event belongs to.
-    pub room_id: RoomId,
-    /// The user id of the user who sent this event.
-    pub sender: UserId,
-    /// The `server_name` of the homeserver that created this event.
-    pub origin: String,
-    /// Timestamp (milliseconds since the UNIX epoch) on originating homeserver
-    /// of when this event was created.
-    #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
-    pub origin_server_ts: SystemTime,
-
-    // TODO: Replace with event content collection from ruma-events once that exists
-    /// The event's type.
-    #[serde(rename = "type")]
-    pub kind: EventType,
-    /// The event's content.
-    pub content: JsonValue,
-
-    /// A key that determines which piece of room state the event represents.
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub state_key: Option<String>,
-    /// Event IDs for the most recent events in the room that the homeserver was
-    /// aware of when it created this event.
-    pub prev_events: Vec<EventId>,
-    /// The maximum depth of the `prev_events`, plus one.
-    pub depth: UInt,
-    /// Event IDs for the authorization events that would allow this event to be
-    /// in the room.
-    pub auth_events: Vec<EventId>,
-    /// For redaction events, the ID of the event being redacted.
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub redacts: Option<EventId>,
-    /// Additional data added by the origin server but not covered by the
-    /// signatures.
-    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-    pub unsigned: BTreeMap<String, JsonValue>,
-    /// Content hashes of the PDU.
-    pub hashes: EventHash,
-    /// Signatures for the PDU.
-    pub signatures: BTreeMap<String, BTreeMap<String, String>>,
-}
-
-/// Content hashes of a PDU.
-#[derive(Clone, Debug, Deserialize, Serialize)]
-pub struct EventHash {
-    /// The SHA-256 hash.
-    pub sha256: String,
-}
+pub mod transactions;
diff --git a/ruma-federation-api/src/membership/create_join_event/mod.rs b/ruma-federation-api/src/membership/create_join_event/mod.rs
index 4c6d2730..4e965454 100644
--- a/ruma-federation-api/src/membership/create_join_event/mod.rs
+++ b/ruma-federation-api/src/membership/create_join_event/mod.rs
@@ -2,11 +2,9 @@
 
 pub mod v1;
 
-use ruma_events::EventJson;
+use ruma_events::{pdu::Pdu, EventJson};
 use serde::{Deserialize, Serialize};
 
-use crate::RoomV3Pdu;
-
 /// Full state of the room.
 #[derive(Clone, Debug, Deserialize, Serialize)]
 pub struct RoomState {
@@ -14,7 +12,7 @@ pub struct RoomState {
     pub origin: String,
     /// The full set of authorization events that make up the state of the room,
     /// and their authorization events, recursively.
-    pub auth_chain: Vec<EventJson<RoomV3Pdu>>,
+    pub auth_chain: Vec<EventJson<Pdu>>,
     /// The room state.
-    pub state: Vec<EventJson<RoomV3Pdu>>,
+    pub state: Vec<EventJson<Pdu>>,
 }
diff --git a/ruma-federation-api/src/membership/create_join_event/v1.rs b/ruma-federation-api/src/membership/create_join_event/v1.rs
index e4403f04..499ce3e9 100644
--- a/ruma-federation-api/src/membership/create_join_event/v1.rs
+++ b/ruma-federation-api/src/membership/create_join_event/v1.rs
@@ -1,15 +1,10 @@
 //! [PUT /_matrix/federation/v1/send_join/{roomId}/{eventId}](https://matrix.org/docs/spec/server_server/r0.1.3#put-matrix-federation-v1-send-join-roomid-eventid)
 
-use std::{collections::BTreeMap, time::SystemTime};
-
-use js_int::UInt;
 use ruma_api::ruma_api;
-use ruma_events::EventType;
-use ruma_identifiers::{EventId, RoomId, UserId};
-use serde_json::Value as JsonValue;
+use ruma_events::pdu::PduStub;
+use ruma_identifiers::{EventId, RoomId};
 
 use super::RoomState;
-use crate::{EventHash, RoomV3Pdu};
 
 ruma_api! {
     metadata {
@@ -29,44 +24,9 @@ ruma_api! {
         #[ruma_api(path)]
         pub event_id: EventId,
 
-        /// The user id of the user who sent this event.
-        pub sender: UserId,
-        /// The `server_name` of the homeserver that created this event.
-        pub origin: String,
-        /// Timestamp (milliseconds since the UNIX epoch) on originating homeserver
-        /// of when this event was created.
-        #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
-        pub origin_server_ts: SystemTime,
-
-        // TODO: Replace with event content collection from ruma-events once that exists
-        /// The event's type.
-        #[serde(rename = "type")]
-        pub kind: EventType,
-        /// The event's content.
-        pub content: JsonValue,
-
-        /// A key that determines which piece of room state the event represents.
-        #[serde(skip_serializing_if = "Option::is_none")]
-        pub state_key: Option<String>,
-        /// Event IDs for the most recent events in the room that the homeserver was
-        /// aware of when it created this event.
-        pub prev_events: Vec<EventId>,
-        /// The maximum depth of the `prev_events`, plus one.
-        pub depth: UInt,
-        /// Event IDs for the authorization events that would allow this event to be
-        /// in the room.
-        pub auth_events: Vec<EventId>,
-        /// For redaction events, the ID of the event being redacted.
-        #[serde(skip_serializing_if = "Option::is_none")]
-        pub redacts: Option<EventId>,
-        /// Additional data added by the origin server but not covered by the
-        /// signatures.
-        #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-        pub unsigned: BTreeMap<String, JsonValue>,
-        /// Content hashes of the PDU.
-        pub hashes: EventHash,
-        /// Signatures for the PDU.
-        pub signatures: BTreeMap<String, BTreeMap<String, String>>,
+        /// PDU type without event and room IDs.
+        #[ruma_api(body)]
+        pub pdu_stub: PduStub,
     }
 
     response {
@@ -76,29 +36,3 @@ ruma_api! {
         pub room_state: RoomState,
     }
 }
-
-impl Request {
-    /// Helper method to get event ID and PDU (with room ID) from the request
-    /// parameters.
-    pub fn into_id_and_v3_pdu(self) -> (EventId, RoomV3Pdu) {
-        (
-            self.event_id,
-            RoomV3Pdu {
-                room_id: self.room_id,
-                sender: self.sender,
-                origin: self.origin,
-                origin_server_ts: self.origin_server_ts,
-                kind: self.kind,
-                content: self.content,
-                state_key: self.state_key,
-                prev_events: self.prev_events,
-                depth: self.depth,
-                auth_events: self.auth_events,
-                redacts: self.redacts,
-                unsigned: self.unsigned,
-                hashes: self.hashes,
-                signatures: self.signatures,
-            },
-        )
-    }
-}
diff --git a/ruma-federation-api/src/membership/create_join_event_template/v1.rs b/ruma-federation-api/src/membership/create_join_event_template/v1.rs
index a25af1fd..84f88699 100644
--- a/ruma-federation-api/src/membership/create_join_event_template/v1.rs
+++ b/ruma-federation-api/src/membership/create_join_event_template/v1.rs
@@ -2,11 +2,9 @@
 
 use js_int::UInt;
 use ruma_api::ruma_api;
-use ruma_events::EventJson;
+use ruma_events::{pdu::Pdu, EventJson};
 use ruma_identifiers::{RoomId, UserId};
 
-use crate::RoomV3Pdu;
-
 ruma_api! {
     metadata {
         description: "Send a request for a join event template to a resident server.",
@@ -34,6 +32,6 @@ ruma_api! {
         /// The version of the room where the server is trying to join.
         pub room_version: Option<UInt>,
         /// An unsigned template event.
-        pub event: EventJson<RoomV3Pdu>,
+        pub event: EventJson<Pdu>,
     }
 }
diff --git a/ruma-federation-api/src/serde.rs b/ruma-federation-api/src/serde.rs
index 3808d8c5..9054a487 100644
--- a/ruma-federation-api/src/serde.rs
+++ b/ruma-federation-api/src/serde.rs
@@ -1,3 +1,4 @@
 //! Modules for custom serde de/-serialization implementations.
 
+pub mod pdu_process_response;
 pub mod room_state;
diff --git a/ruma-federation-api/src/serde/pdu_process_response.rs b/ruma-federation-api/src/serde/pdu_process_response.rs
new file mode 100644
index 00000000..57c0a807
--- /dev/null
+++ b/ruma-federation-api/src/serde/pdu_process_response.rs
@@ -0,0 +1,156 @@
+use std::{collections::BTreeMap, fmt};
+
+use ruma_identifiers::EventId;
+use serde::{
+    de::{Deserializer, MapAccess, Visitor},
+    ser::{SerializeMap, Serializer},
+    Deserialize, Serialize,
+};
+
+pub fn serialize<S>(
+    response: &BTreeMap<EventId, Result<(), String>>,
+    serializer: S,
+) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    let mut map = serializer.serialize_map(Some(response.len()))?;
+    for (key, value) in response {
+        let wrapped_error = WrappedError {
+            error: match value {
+                Ok(_) => None,
+                Err(error) => Some(error.clone()),
+            },
+        };
+        map.serialize_entry(&key, &wrapped_error)?;
+    }
+    map.end()
+}
+
+pub fn deserialize<'de, D>(
+    deserializer: D,
+) -> Result<BTreeMap<EventId, Result<(), String>>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    deserializer.deserialize_map(PduProcessResponseVisitor)
+}
+
+#[derive(Deserialize, Serialize)]
+struct WrappedError {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    error: Option<String>,
+}
+
+struct PduProcessResponseVisitor;
+
+impl<'de> Visitor<'de> for PduProcessResponseVisitor {
+    type Value = BTreeMap<EventId, Result<(), String>>;
+
+    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("A map of EventIds to a map of optional errors")
+    }
+
+    fn visit_map<M>(self, mut access: M) -> Result<Self::Value, M::Error>
+    where
+        M: MapAccess<'de>,
+    {
+        let mut map = BTreeMap::new();
+
+        while let Some((key, value)) = access.next_entry::<EventId, WrappedError>()? {
+            let v = match value.error {
+                None => Ok(()),
+                Some(error) => Err(error),
+            };
+            map.insert(key, v);
+        }
+        Ok(map)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::{collections::BTreeMap, convert::TryFrom};
+
+    use ruma_identifiers::EventId;
+    use serde_json::{json, value::Serializer as JsonSerializer};
+
+    use super::{deserialize, serialize};
+
+    #[test]
+    fn serialize_error() {
+        let mut response: BTreeMap<EventId, Result<(), String>> = BTreeMap::new();
+        response.insert(
+            EventId::try_from("$someevent:matrix.org").unwrap(),
+            Err("Some processing error.".into()),
+        );
+
+        let serialized = serialize(&response, JsonSerializer).unwrap();
+        let json = json!({
+            "$someevent:matrix.org": { "error": "Some processing error." }
+        });
+        assert_eq!(serialized, json);
+    }
+
+    #[test]
+    fn serialize_ok() {
+        let mut response: BTreeMap<EventId, Result<(), String>> = BTreeMap::new();
+        response.insert(EventId::try_from("$someevent:matrix.org").unwrap(), Ok(()));
+
+        let serialized = serialize(&response, serde_json::value::Serializer).unwrap();
+        let json = json!({
+            "$someevent:matrix.org": {}
+        });
+        assert_eq!(serialized, json);
+    }
+
+    #[test]
+    fn deserialize_error() {
+        let json = json!({
+            "$someevent:matrix.org": { "error": "Some processing error." }
+        });
+
+        let response = deserialize(json).unwrap();
+        let event_id = EventId::try_from("$someevent:matrix.org").unwrap();
+
+        let event_response = response.get(&event_id).unwrap().clone().unwrap_err();
+        assert_eq!(event_response, "Some processing error.");
+    }
+
+    #[test]
+    fn deserialize_null_error_is_ok() {
+        let json = json!({
+            "$someevent:matrix.org": { "error": null }
+        });
+
+        let response = deserialize(json).unwrap();
+        let event_id = EventId::try_from("$someevent:matrix.org").unwrap();
+
+        assert!(response.get(&event_id).unwrap().is_ok());
+    }
+
+    #[test]
+    fn desieralize_empty_error_is_err() {
+        let json = json!({
+            "$someevent:matrix.org": { "error": "" }
+        });
+
+        let response = deserialize(json).unwrap();
+        let event_id = EventId::try_from("$someevent:matrix.org").unwrap();
+
+        let event_response = response.get(&event_id).unwrap().clone().unwrap_err();
+        assert_eq!(event_response, "");
+    }
+
+    #[test]
+    fn deserialize_ok() {
+        let json = json!({
+            "$someevent:matrix.org": {}
+        });
+        let response = deserialize(json).unwrap();
+        assert!(response
+            .get(&EventId::try_from("$someevent:matrix.org").unwrap())
+            .unwrap()
+            .is_ok());
+    }
+}
diff --git a/ruma-federation-api/src/transactions.rs b/ruma-federation-api/src/transactions.rs
new file mode 100644
index 00000000..e889b1f5
--- /dev/null
+++ b/ruma-federation-api/src/transactions.rs
@@ -0,0 +1,3 @@
+//! Endpoints for exchanging transaction messages between homeservers.
+
+pub mod send_transaction_message;
diff --git a/ruma-federation-api/src/transactions/send_transaction_message/mod.rs b/ruma-federation-api/src/transactions/send_transaction_message/mod.rs
new file mode 100644
index 00000000..135bfb5f
--- /dev/null
+++ b/ruma-federation-api/src/transactions/send_transaction_message/mod.rs
@@ -0,0 +1,3 @@
+//! Endpoint to send live activity messages to another server.
+
+pub mod v1;
diff --git a/ruma-federation-api/src/transactions/send_transaction_message/v1.rs b/ruma-federation-api/src/transactions/send_transaction_message/v1.rs
new file mode 100644
index 00000000..0bc8f805
--- /dev/null
+++ b/ruma-federation-api/src/transactions/send_transaction_message/v1.rs
@@ -0,0 +1,59 @@
+//! [PUT /_matrix/federation/v1/send/{txnId}](https://matrix.org/docs/spec/server_server/r0.1.3#put-matrix-federation-v1-send-txnid)
+
+use std::{collections::BTreeMap, time::SystemTime};
+
+use ruma_api::ruma_api;
+use ruma_events::pdu::Pdu;
+use ruma_identifiers::EventId;
+use serde::{Deserialize, Serialize};
+use serde_json::Value as JsonValue;
+
+ruma_api! {
+    metadata {
+        description: "Send transaction messages to another server",
+        name: "send_transaction_message",
+        method: PUT,
+        path: "/_matrix/federation/v1/send/:transaction_id",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// A transaction ID unique between sending and receiving homeservers.
+        #[ruma_api(path)]
+        pub transaction_id: String,
+
+        /// The server_name of the homeserver sending this transaction.
+        pub origin: String,
+
+        /// POSIX timestamp in milliseconds on the originating homeserver when this transaction started.
+        #[serde(with = "ruma_serde::time::ms_since_unix_epoch")]
+        pub origin_server_ts: SystemTime,
+
+        /// List of persistent updates to rooms.
+        ///
+        /// Must not be more than 50 items.
+        pub pdus: Vec<Pdu>,
+
+        /// List of ephemeral messages.
+        ///
+        /// Must not be more than 100 items.
+        #[serde(skip_serializing_if = "Vec::is_empty")]
+        pub edus: Vec<Edu>,
+    }
+
+    response {
+        /// Map of event IDs and response for each PDU given in the request.
+        #[serde(with = "crate::serde::pdu_process_response")]
+        pub pdus: BTreeMap<EventId, Result<(), String>>,
+    }
+}
+
+/// Type for passing ephemeral data to homeservers.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct Edu {
+    /// Type of the ephemeral message.
+    pub edu_type: String,
+    /// Content of ephemeral message
+    pub content: JsonValue,
+}