diff --git a/ruma-appservice-api/.builds/beta.yml b/ruma-appservice-api/.builds/beta.yml
new file mode 100644
index 00000000..ec105e03
--- /dev/null
+++ b/ruma-appservice-api/.builds/beta.yml
@@ -0,0 +1,27 @@
+image: archlinux
+packages:
+  - rustup
+sources:
+  - https://github.com/ruma/ruma-appservice-api
+tasks:
+  - rustup: |
+      # We specify --profile minimal because we'd otherwise download docs
+      rustup toolchain install beta --profile minimal -c rustfmt -c clippy
+      rustup default beta
+  - test: |
+      cd ruma-appservice-api
+
+      # We don't want the build to stop on individual failure of independent
+      # tools, so capture tool exit codes and set the task exit code manually
+      set +e
+
+      cargo fmt -- --check
+      fmt_exit=$?
+
+      cargo clippy --all-targets --all-features -- -D warnings
+      clippy_exit=$?
+
+      cargo test --verbose
+      test_exit=$?
+
+      exit $(( $fmt_exit || $clippy_exit || $test_exit ))
diff --git a/ruma-appservice-api/.builds/msrv.yml b/ruma-appservice-api/.builds/msrv.yml
new file mode 100644
index 00000000..635bffdb
--- /dev/null
+++ b/ruma-appservice-api/.builds/msrv.yml
@@ -0,0 +1,16 @@
+image: archlinux
+packages:
+  - rustup
+sources:
+  - https://github.com/ruma/ruma-appservice-api
+tasks:
+  - rustup: |
+      # We specify --profile minimal because we'd otherwise download docs
+      rustup toolchain install 1.39.0 --profile minimal
+      rustup default 1.39.0
+  - test: |
+      cd ruma-appservice-api
+
+      # Only make sure the code builds with the MSRV. Tests can require later
+      # Rust versions, don't compile or run them.
+      cargo build --verbose
diff --git a/ruma-appservice-api/.builds/nightly.yml b/ruma-appservice-api/.builds/nightly.yml
new file mode 100644
index 00000000..72c98254
--- /dev/null
+++ b/ruma-appservice-api/.builds/nightly.yml
@@ -0,0 +1,32 @@
+image: archlinux
+packages:
+  - rustup
+sources:
+  - https://github.com/ruma/ruma-appservice-api
+tasks:
+  - rustup: |
+      rustup toolchain install nightly --profile minimal
+      rustup default nightly
+
+      # Try installing rustfmt & clippy for nightly, but don't fail the build
+      # if they are not available
+      rustup component add rustfmt || true
+      rustup component add clippy || true
+  - test: |
+      cd ruma-appservice-api
+
+      # We don't want the build to stop on individual failure of independent
+      # tools, so capture tool exit codes and set the task exit code manually
+      set +e
+
+      if ( rustup component list | grep -q rustfmt ); then
+        cargo fmt -- --check
+      fi
+      fmt_exit=$?
+
+      if ( rustup component list | grep -q clippy ); then
+        cargo clippy --all-targets --all-features -- -D warnings
+      fi
+      clippy_exit=$?
+
+      exit $(( $fmt_exit || $clippy_exit ))
diff --git a/ruma-appservice-api/.builds/stable.yml b/ruma-appservice-api/.builds/stable.yml
new file mode 100644
index 00000000..28b8f0ff
--- /dev/null
+++ b/ruma-appservice-api/.builds/stable.yml
@@ -0,0 +1,29 @@
+image: archlinux
+packages:
+  - rustup
+sources:
+  - https://github.com/ruma/ruma-appservice-api
+tasks:
+  - rustup: |
+      # We specify --profile minimal because we'd otherwise download docs
+      rustup toolchain install stable --profile minimal -c rustfmt -c clippy
+      rustup default stable
+  - test: |
+      cd ruma-appservice-api
+
+      # We don't want the build to stop on individual failure of independent
+      # tools, so capture tool exit codes and set the task exit code manually
+      set +e
+
+      cargo fmt -- --check
+      fmt_exit=$?
+
+      cargo clippy --all-targets --all-features -- -D warnings
+      clippy_exit=$?
+
+      cargo test --verbose
+      test_exit=$?
+
+      exit $(( $fmt_exit || $clippy_exit || $test_exit ))
+  # TODO: Add audit task once cargo-audit binary releases are available.
+  #       See https://github.com/RustSec/cargo-audit/issues/66
diff --git a/ruma-appservice-api/.gitignore b/ruma-appservice-api/.gitignore
new file mode 100644
index 00000000..fa8d85ac
--- /dev/null
+++ b/ruma-appservice-api/.gitignore
@@ -0,0 +1,2 @@
+Cargo.lock
+target
diff --git a/ruma-appservice-api/CHANGELOG.md b/ruma-appservice-api/CHANGELOG.md
new file mode 100644
index 00000000..69afd520
--- /dev/null
+++ b/ruma-appservice-api/CHANGELOG.md
@@ -0,0 +1,3 @@
+# 0.1.0
+
+Initial release.
diff --git a/ruma-appservice-api/Cargo.toml b/ruma-appservice-api/Cargo.toml
new file mode 100644
index 00000000..6aa3f802
--- /dev/null
+++ b/ruma-appservice-api/Cargo.toml
@@ -0,0 +1,20 @@
+[package]
+authors = ["Wim de With <wf@dewith.io>"]
+categories = ["api-bindings", "web-programming"]
+description = "Types for the endpoints in the Matrix application service API."
+homepage = "https://github.com/ruma/ruma-appservice-api"
+keywords = ["matrix", "chat", "messaging", "ruma"]
+license = "MIT"
+name = "ruma-appservice-api"
+readme = "README.md"
+repository = "https://github.com/ruma/ruma-appservice-api"
+version = "0.1.0"
+edition = "2018"
+
+[dependencies]
+ruma-api = "0.16.0"
+ruma-events = "0.21.0"
+ruma-identifiers = "0.16.1"
+serde = { version = "1.0.106", features = ["derive"] }
+serde_json = "1.0.52"
+url = { version = "2.1.1", features = ["serde"] }
diff --git a/ruma-appservice-api/LICENSE b/ruma-appservice-api/LICENSE
new file mode 100644
index 00000000..da7c1156
--- /dev/null
+++ b/ruma-appservice-api/LICENSE
@@ -0,0 +1,19 @@
+Copyright (c) 2019 Wim de With
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/ruma-appservice-api/README.md b/ruma-appservice-api/README.md
new file mode 100644
index 00000000..7d010ee5
--- /dev/null
+++ b/ruma-appservice-api/README.md
@@ -0,0 +1,16 @@
+# ruma-appservice-api
+
+**ruma-appservice-api** contains serializable types for the requests and responses for each endpoint in the [Matrix](https://matrix.org/) application service API specification.
+These types can be shared by application service and server code.
+
+## Minimum Rust version
+
+ruma-appservice-api requires Rust 1.39.0 or later.
+
+## Status
+
+This project is currently experimental and is very likely to change drastically.
+
+## License
+
+[MIT](http://opensource.org/licenses/MIT)
diff --git a/ruma-appservice-api/src/lib.rs b/ruma-appservice-api/src/lib.rs
new file mode 100644
index 00000000..a6372d51
--- /dev/null
+++ b/ruma-appservice-api/src/lib.rs
@@ -0,0 +1,13 @@
+//! Crate ruma_appservice_api contains serializable types for the requests and responses for each
+//! endpoint in the [Matrix](https://matrix.org/) application service API specification. These
+//! types can be shared by application service and server code.
+
+#![deny(
+    missing_copy_implementations,
+    missing_debug_implementations,
+    missing_docs
+)]
+// Since we support Rust 1.34.2, we can't apply this suggestion yet
+#![allow(clippy::use_self)]
+
+pub mod v1;
diff --git a/ruma-appservice-api/src/v1.rs b/ruma-appservice-api/src/v1.rs
new file mode 100644
index 00000000..75499ade
--- /dev/null
+++ b/ruma-appservice-api/src/v1.rs
@@ -0,0 +1,5 @@
+//! Endpoints for the r0.x.x versions of the application service API specification
+
+pub mod event;
+pub mod query;
+pub mod thirdparty;
diff --git a/ruma-appservice-api/src/v1/event.rs b/ruma-appservice-api/src/v1/event.rs
new file mode 100644
index 00000000..8721e54f
--- /dev/null
+++ b/ruma-appservice-api/src/v1/event.rs
@@ -0,0 +1,3 @@
+//! Endpoint for sending events.
+
+pub mod push_events;
diff --git a/ruma-appservice-api/src/v1/event/push_events.rs b/ruma-appservice-api/src/v1/event/push_events.rs
new file mode 100644
index 00000000..bef1ec46
--- /dev/null
+++ b/ruma-appservice-api/src/v1/event/push_events.rs
@@ -0,0 +1,28 @@
+//! [PUT /_matrix/app/v1/transactions/{txnId}](https://matrix.org/docs/spec/application_service/r0.1.2#put-matrix-app-v1-transactions-txnid)
+
+use ruma_api::ruma_api;
+use ruma_events::{collections::all, EventJson};
+
+ruma_api! {
+    metadata {
+        description: "This API is called by the homeserver when it wants to push an event (or batch of events) to the application service.",
+        method: PUT,
+        name: "push_events",
+        path: "/_matrix/app/v1/transactions/:txn_id",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// The transaction ID for this set of events.
+        ///
+        /// Homeservers generate these IDs and they are used to ensure idempotency of results.
+        #[ruma_api(path)]
+        pub txn_id: String,
+        /// A list of events.
+        #[ruma_api(body)]
+        pub events: Vec<EventJson<all::Event>>,
+    }
+
+    response {}
+}
diff --git a/ruma-appservice-api/src/v1/query.rs b/ruma-appservice-api/src/v1/query.rs
new file mode 100644
index 00000000..ee67d7b8
--- /dev/null
+++ b/ruma-appservice-api/src/v1/query.rs
@@ -0,0 +1,4 @@
+//! Endpoints for querying user IDs and room aliases
+
+pub mod query_room_alias;
+pub mod query_user_id;
diff --git a/ruma-appservice-api/src/v1/query/query_room_alias.rs b/ruma-appservice-api/src/v1/query/query_room_alias.rs
new file mode 100644
index 00000000..ea0e17fe
--- /dev/null
+++ b/ruma-appservice-api/src/v1/query/query_room_alias.rs
@@ -0,0 +1,23 @@
+//! [GET /_matrix/app/v1/rooms/{roomAlias}](https://matrix.org/docs/spec/application_service/r0.1.2#get-matrix-app-v1-rooms-roomalias)
+
+use ruma_api::ruma_api;
+use ruma_identifiers::RoomAliasId;
+
+ruma_api! {
+    metadata {
+        description: "This endpoint is invoked by the homeserver on an application service to query the existence of a given room alias.",
+        method: GET,
+        name: "query_room_alias",
+        path: "/_matrix/app/v1/rooms/:room_alias",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// The room alias being queried.
+        #[ruma_api(path)]
+        pub room_alias: RoomAliasId,
+    }
+
+    response {}
+}
diff --git a/ruma-appservice-api/src/v1/query/query_user_id.rs b/ruma-appservice-api/src/v1/query/query_user_id.rs
new file mode 100644
index 00000000..d45cccc3
--- /dev/null
+++ b/ruma-appservice-api/src/v1/query/query_user_id.rs
@@ -0,0 +1,23 @@
+//! [GET /_matrix/app/v1/users/{userId}](https://matrix.org/docs/spec/application_service/r0.1.2#get-matrix-app-v1-users-userid)
+
+use ruma_api::ruma_api;
+use ruma_identifiers::UserId;
+
+ruma_api! {
+    metadata {
+        description: "This endpoint is invoked by the homeserver on an application service to query the existence of a given user ID.",
+        method: GET,
+        name: "query_user_id",
+        path: "/_matrix/app/v1/users/:user_id",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// The user ID being queried.
+        #[ruma_api(path)]
+        pub user_id: UserId,
+    }
+
+    response {}
+}
diff --git a/ruma-appservice-api/src/v1/thirdparty.rs b/ruma-appservice-api/src/v1/thirdparty.rs
new file mode 100644
index 00000000..16e40245
--- /dev/null
+++ b/ruma-appservice-api/src/v1/thirdparty.rs
@@ -0,0 +1,73 @@
+//! Endpoints for third party lookups
+
+pub mod get_location_for_protocol;
+pub mod get_location_for_room_alias;
+pub mod get_protocol;
+pub mod get_user_for_protocol;
+pub mod get_user_for_user_id;
+
+use std::collections::BTreeMap;
+
+use ruma_identifiers::{RoomAliasId, UserId};
+
+use serde::{Deserialize, Serialize};
+
+/// Metadata about a third party protocol.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct Protocol {
+    /// Fields which may be used to identify a third party user.
+    pub user_fields: Vec<String>,
+    /// Fields which may be used to identify a third party location.
+    pub location_fields: Vec<String>,
+    /// A content URI representing an icon for the third party protocol.
+    pub icon: String,
+    /// The type definitions for the fields defined in `user_fields` and `location_fields`.
+    pub field_types: BTreeMap<String, FieldType>,
+    /// A list of objects representing independent instances of configuration.
+    pub instances: Vec<ProtocolInstance>,
+}
+
+/// Metadata about an instance of a third party protocol.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct ProtocolInstance {
+    /// A human-readable description for the protocol, such as the name.
+    pub desc: String,
+    /// An optional content URI representing the protocol.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub icon: Option<String>,
+    /// Preset values for `fields` the client may use to search by.
+    pub fields: BTreeMap<String, String>,
+    /// A unique identifier across all instances.
+    pub network_id: String,
+}
+
+/// A type definition for a field used to identify third party users or locations.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct FieldType {
+    /// A regular expression for validation of a field's value.
+    pub regexp: String,
+    /// A placeholder serving as a valid example of the field value.
+    pub placeholder: String,
+}
+
+/// A third party network location.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct Location {
+    /// An alias for a matrix room.
+    pub alias: RoomAliasId,
+    /// The protocol ID that the third party location is a part of.
+    pub protocol: String,
+    /// Information used to identify this third party location.
+    pub fields: BTreeMap<String, String>,
+}
+
+/// A third party network user.
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct User {
+    /// A matrix user ID representing a third party user.
+    pub userid: UserId,
+    /// The protocol ID that the third party user is a part of.
+    pub protocol: String,
+    /// Information used to identify this third party user.
+    pub fields: BTreeMap<String, String>,
+}
diff --git a/ruma-appservice-api/src/v1/thirdparty/get_location_for_protocol.rs b/ruma-appservice-api/src/v1/thirdparty/get_location_for_protocol.rs
new file mode 100644
index 00000000..6c791fd3
--- /dev/null
+++ b/ruma-appservice-api/src/v1/thirdparty/get_location_for_protocol.rs
@@ -0,0 +1,34 @@
+//! [GET /_matrix/app/v1/thirdparty/location/{protocol}](https://matrix.org/docs/spec/application_service/r0.1.2#get-matrix-app-v1-thirdparty-location-protocol)
+
+use std::collections::BTreeMap;
+
+use ruma_api::ruma_api;
+
+use super::Location;
+
+ruma_api! {
+    metadata {
+        description: "Fetches third party locations for a protocol.",
+        method: GET,
+        name: "get_location_for_protocol",
+        path: "/_matrix/app/v1/thirdparty/location/:protocol",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// The protocol used to communicate to the third party network.
+        #[ruma_api(path)]
+        pub protocol: String,
+        /// One or more custom fields to help identify the third party location.
+        // The specification is incorrect for this parameter. See matrix-org/matrix-doc#2352.
+        #[ruma_api(query_map)]
+        pub fields: BTreeMap<String, String>,
+    }
+
+    response {
+        /// List of matched third party locations.
+        #[ruma_api(body)]
+        pub locations: Vec<Location>,
+    }
+}
diff --git a/ruma-appservice-api/src/v1/thirdparty/get_location_for_room_alias.rs b/ruma-appservice-api/src/v1/thirdparty/get_location_for_room_alias.rs
new file mode 100644
index 00000000..270e2661
--- /dev/null
+++ b/ruma-appservice-api/src/v1/thirdparty/get_location_for_room_alias.rs
@@ -0,0 +1,29 @@
+//! [GET /_matrix/app/v1/thirdparty/location](https://matrix.org/docs/spec/application_service/r0.1.2#get-matrix-app-v1-thirdparty-location)
+
+use ruma_api::ruma_api;
+use ruma_identifiers::RoomAliasId;
+
+use super::Location;
+
+ruma_api! {
+    metadata {
+        description: "Retrieve an array of third party network locations from a Matrix room alias.",
+        method: GET,
+        name: "get_location_for_room_alias",
+        path: "/_matrix/app/v1/thirdparty/location",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// The Matrix room alias to look up.
+        #[ruma_api(query)]
+        pub alias: RoomAliasId,
+    }
+
+    response {
+        /// List of matched third party locations.
+        #[ruma_api(body)]
+        pub locations: Vec<Location>,
+    }
+}
diff --git a/ruma-appservice-api/src/v1/thirdparty/get_protocol.rs b/ruma-appservice-api/src/v1/thirdparty/get_protocol.rs
new file mode 100644
index 00000000..726336c6
--- /dev/null
+++ b/ruma-appservice-api/src/v1/thirdparty/get_protocol.rs
@@ -0,0 +1,28 @@
+//! [GET /_matrix/app/v1/thirdparty/protocol/{protocol}](https://matrix.org/docs/spec/application_service/r0.1.2#get-matrix-app-v1-thirdparty-protocol-protocol)
+
+use ruma_api::ruma_api;
+
+use super::Protocol;
+
+ruma_api! {
+    metadata {
+        description: "Fetches the metadata from the homeserver about a particular third party protocol.",
+        method: GET,
+        name: "get_protocol",
+        path: "/_matrix/app/v1/thirdparty/protocol/:protocol",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// The name of the protocol.
+        #[ruma_api(path)]
+        pub protocol: String,
+    }
+
+    response {
+        /// Metadata about the protocol.
+        #[ruma_api(body)]
+        pub protocol: Protocol,
+    }
+}
diff --git a/ruma-appservice-api/src/v1/thirdparty/get_user_for_protocol.rs b/ruma-appservice-api/src/v1/thirdparty/get_user_for_protocol.rs
new file mode 100644
index 00000000..f9fb14a2
--- /dev/null
+++ b/ruma-appservice-api/src/v1/thirdparty/get_user_for_protocol.rs
@@ -0,0 +1,34 @@
+//! [GET /_matrix/app/v1/thirdparty/user/{protocol}](https://matrix.org/docs/spec/application_service/r0.1.2#get-matrix-app-v1-thirdparty-user-protocol)
+
+use std::collections::BTreeMap;
+
+use ruma_api::ruma_api;
+
+use super::User;
+
+ruma_api! {
+    metadata {
+        description: "Fetches third party users for a protocol.",
+        method: GET,
+        name: "get_user_for_protocol",
+        path: "/_matrix/app/v1/thirdparty/user/:protocol",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// The protocol used to communicate to the third party network.
+        #[ruma_api(path)]
+        pub protocol: String,
+        /// One or more custom fields that are passed to the AS to help identify the user.
+        // The specification is incorrect for this parameter. See matrix-org/matrix-doc#2352.
+        #[ruma_api(query_map)]
+        pub fields: BTreeMap<String, String>,
+    }
+
+    response {
+        /// List of matched third party users.
+        #[ruma_api(body)]
+        pub users: Vec<User>,
+    }
+}
diff --git a/ruma-appservice-api/src/v1/thirdparty/get_user_for_user_id.rs b/ruma-appservice-api/src/v1/thirdparty/get_user_for_user_id.rs
new file mode 100644
index 00000000..7ac655ef
--- /dev/null
+++ b/ruma-appservice-api/src/v1/thirdparty/get_user_for_user_id.rs
@@ -0,0 +1,29 @@
+//! [GET /_matrix/app/v1/thirdparty/user](https://matrix.org/docs/spec/application_service/r0.1.2#get-matrix-app-v1-thirdparty-user)
+
+use ruma_api::ruma_api;
+use ruma_identifiers::UserId;
+
+use super::User;
+
+ruma_api! {
+    metadata {
+        description: "Retrieve an array of third party users from a Matrix User ID.",
+        method: GET,
+        name: "get_user_for_user_id",
+        path: "/_matrix/app/v1/thirdparty/user",
+        rate_limited: false,
+        requires_authentication: true,
+    }
+
+    request {
+        /// The Matrix User ID to look up.
+        #[ruma_api(query)]
+        pub userid: UserId,
+    }
+
+    response {
+        /// List of matched third party users.
+        #[ruma_api(body)]
+        pub users: Vec<User>,
+    }
+}