diff --git a/src/api/client_server/mod.rs b/src/api/client_server/mod.rs
index afe5181e..a35d7a98 100644
--- a/src/api/client_server/mod.rs
+++ b/src/api/client_server/mod.rs
@@ -11,6 +11,7 @@ mod keys;
 mod media;
 mod membership;
 mod message;
+mod openid;
 mod presence;
 mod profile;
 mod push;
@@ -47,6 +48,7 @@ pub use keys::*;
 pub use media::*;
 pub use membership::*;
 pub use message::*;
+pub use openid::*;
 pub use presence::*;
 pub use profile::*;
 pub use push::*;
diff --git a/src/api/client_server/openid.rs b/src/api/client_server/openid.rs
new file mode 100644
index 00000000..42160410
--- /dev/null
+++ b/src/api/client_server/openid.rs
@@ -0,0 +1,23 @@
+use std::time::Duration;
+
+use ruma::{api::client::account, authentication::TokenType};
+
+use crate::{services, Result, Ruma};
+
+/// # `POST /_matrix/client/r0/user/{userId}/openid/request_token`
+///
+/// Request an OpenID token to verify identity with third-party services.
+///
+/// - The token generated is only valid for the OpenID API.
+pub async fn create_openid_token_route(
+    body: Ruma<account::request_openid_token::v3::Request>,
+) -> Result<account::request_openid_token::v3::Response> {
+    let (access_token, expires_in) = services().users.create_openid_token(&body.user_id)?;
+
+    Ok(account::request_openid_token::v3::Response {
+        access_token,
+        token_type: TokenType::Bearer,
+        matrix_server_name: services().globals.server_name().to_owned(),
+        expires_in: Duration::from_secs(expires_in),
+    })
+}
diff --git a/src/api/ruma_wrapper/axum.rs b/src/api/ruma_wrapper/axum.rs
index a56ee359..f5ef6050 100644
--- a/src/api/ruma_wrapper/axum.rs
+++ b/src/api/ruma_wrapper/axum.rs
@@ -102,10 +102,15 @@ where
         let (sender_user, sender_device, sender_servername, appservice_info) =
             match (metadata.authentication, token) {
                 (_, Token::Invalid) => {
-                    return Err(Error::BadRequest(
-                        ErrorKind::UnknownToken { soft_logout: false },
-                        "Unknown access token.",
-                    ))
+                    // OpenID endpoint uses a query param with the same name, drop this once query params for user auth are removed from the spec
+                    if query_params.access_token.is_some() {
+                        (None, None, None, None)
+                    } else {
+                        return Err(Error::BadRequest(
+                            ErrorKind::UnknownToken { soft_logout: false },
+                            "Unknown access token.",
+                        ));
+                    }
                 }
                 (AuthScheme::AccessToken, Token::Appservice(info)) => {
                     let user_id = query_params
diff --git a/src/api/server_server.rs b/src/api/server_server.rs
index 6ca352b8..13a6d648 100644
--- a/src/api/server_server.rs
+++ b/src/api/server_server.rs
@@ -24,6 +24,7 @@ use ruma::{
             event::{get_event, get_missing_events, get_room_state, get_room_state_ids},
             keys::{claim_keys, get_keys},
             membership::{create_invite, create_join_event, prepare_join_event},
+            openid::get_openid_userinfo,
             query::{get_profile_information, get_room_information},
             transactions::{
                 edu::{DeviceListUpdateContent, DirectDeviceContent, Edu, SigningKeyUpdateContent},
@@ -1914,6 +1915,25 @@ pub async fn claim_keys_route(
     })
 }
 
+/// # `GET /_matrix/federation/v1/openid/userinfo`
+///
+/// Get information about the user that generated the OpenID token.
+pub async fn get_openid_userinfo_route(
+    body: Ruma<get_openid_userinfo::v1::Request>,
+) -> Result<get_openid_userinfo::v1::Response> {
+    Ok(get_openid_userinfo::v1::Response::new(
+        services()
+            .users
+            .find_from_openid_token(&body.access_token)?
+            .ok_or_else(|| {
+                Error::BadRequest(
+                    ErrorKind::Unauthorized,
+                    "OpenID token has expired or does not exist.",
+                )
+            })?,
+    ))
+}
+
 /// # `GET /.well-known/matrix/server`
 ///
 /// Returns the federation server discovery information.
diff --git a/src/config/mod.rs b/src/config/mod.rs
index 652b3a4c..378ab929 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -47,6 +47,8 @@ pub struct Config {
     #[serde(default = "false_fn")]
     pub allow_registration: bool,
     pub registration_token: Option<String>,
+    #[serde(default = "default_openid_token_ttl")]
+    pub openid_token_ttl: u64,
     #[serde(default = "true_fn")]
     pub allow_encryption: bool,
     #[serde(default = "false_fn")]
@@ -302,6 +304,10 @@ fn default_turn_ttl() -> u64 {
     60 * 60 * 24
 }
 
+fn default_openid_token_ttl() -> u64 {
+    60 * 60
+}
+
 // I know, it's a great name
 pub fn default_default_room_version() -> RoomVersionId {
     RoomVersionId::V10
diff --git a/src/database/key_value/users.rs b/src/database/key_value/users.rs
index 0e6db83a..63321a40 100644
--- a/src/database/key_value/users.rs
+++ b/src/database/key_value/users.rs
@@ -11,6 +11,7 @@ use ruma::{
 use tracing::warn;
 
 use crate::{
+    api::client_server::TOKEN_LENGTH,
     database::KeyValueDatabase,
     service::{self, users::clean_signatures},
     services, utils, Error, Result,
@@ -943,6 +944,52 @@ impl service::users::Data for KeyValueDatabase {
             Ok(None)
         }
     }
+
+    // Creates an OpenID token, which can be used to prove that a user has access to an account (primarily for integrations)
+    fn create_openid_token(&self, user_id: &UserId) -> Result<(String, u64)> {
+        let token = utils::random_string(TOKEN_LENGTH);
+
+        let expires_in = services().globals.config.openid_token_ttl;
+        let expires_at = utils::millis_since_unix_epoch()
+            .checked_add(expires_in * 1000)
+            .expect("time is valid");
+
+        let mut value = expires_at.to_be_bytes().to_vec();
+        value.extend_from_slice(user_id.as_bytes());
+
+        self.openidtoken_expiresatuserid
+            .insert(token.as_bytes(), value.as_slice())?;
+
+        Ok((token, expires_in))
+    }
+
+    /// Find out which user an OpenID access token belongs to.
+    fn find_from_openid_token(&self, token: &str) -> Result<Option<OwnedUserId>> {
+        let Some(value) = self.openidtoken_expiresatuserid.get(token.as_bytes())? else {
+            return Ok(None);
+        };
+        let (expires_at_bytes, user_bytes) = value.split_at(0u64.to_be_bytes().len());
+
+        let expires_at = u64::from_be_bytes(
+            expires_at_bytes
+                .try_into()
+                .map_err(|_| Error::bad_database("expires_at in openid_userid is invalid u64."))?,
+        );
+
+        if expires_at < utils::millis_since_unix_epoch() {
+            self.openidtoken_expiresatuserid.remove(token.as_bytes())?;
+
+            return Ok(None);
+        }
+
+        Some(
+            UserId::parse(utils::string_from_bytes(user_bytes).map_err(|_| {
+                Error::bad_database("User ID in openid_userid is invalid unicode.")
+            })?)
+            .map_err(|_| Error::bad_database("User ID in openid_userid is invalid.")),
+        )
+        .transpose()
+    }
 }
 
 impl KeyValueDatabase {}
diff --git a/src/database/mod.rs b/src/database/mod.rs
index 8d1b1913..f4740ff4 100644
--- a/src/database/mod.rs
+++ b/src/database/mod.rs
@@ -57,6 +57,7 @@ pub struct KeyValueDatabase {
     pub(super) userid_masterkeyid: Arc<dyn KvTree>,
     pub(super) userid_selfsigningkeyid: Arc<dyn KvTree>,
     pub(super) userid_usersigningkeyid: Arc<dyn KvTree>,
+    pub(super) openidtoken_expiresatuserid: Arc<dyn KvTree>, // expiresatuserid  = expiresat + userid
 
     pub(super) userfilterid_filter: Arc<dyn KvTree>, // UserFilterId = UserId + FilterId
 
@@ -290,6 +291,7 @@ impl KeyValueDatabase {
             userid_masterkeyid: builder.open_tree("userid_masterkeyid")?,
             userid_selfsigningkeyid: builder.open_tree("userid_selfsigningkeyid")?,
             userid_usersigningkeyid: builder.open_tree("userid_usersigningkeyid")?,
+            openidtoken_expiresatuserid: builder.open_tree("openidtoken_expiresatuserid")?,
             userfilterid_filter: builder.open_tree("userfilterid_filter")?,
             todeviceid_events: builder.open_tree("todeviceid_events")?,
 
diff --git a/src/main.rs b/src/main.rs
index 5d60a6bf..6eeff9a0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -277,6 +277,7 @@ fn routes(config: &Config) -> Router {
         .ruma_route(client_server::get_room_aliases_route)
         .ruma_route(client_server::get_filter_route)
         .ruma_route(client_server::create_filter_route)
+        .ruma_route(client_server::create_openid_token_route)
         .ruma_route(client_server::set_global_account_data_route)
         .ruma_route(client_server::set_room_account_data_route)
         .ruma_route(client_server::get_global_account_data_route)
@@ -431,6 +432,7 @@ fn routes(config: &Config) -> Router {
             .ruma_route(server_server::get_profile_information_route)
             .ruma_route(server_server::get_keys_route)
             .ruma_route(server_server::claim_keys_route)
+            .ruma_route(server_server::get_openid_userinfo_route)
             .ruma_route(server_server::well_known_server)
     } else {
         router
diff --git a/src/service/users/data.rs b/src/service/users/data.rs
index ddf941e3..4566c36d 100644
--- a/src/service/users/data.rs
+++ b/src/service/users/data.rs
@@ -211,4 +211,10 @@ pub trait Data: Send + Sync {
     fn create_filter(&self, user_id: &UserId, filter: &FilterDefinition) -> Result<String>;
 
     fn get_filter(&self, user_id: &UserId, filter_id: &str) -> Result<Option<FilterDefinition>>;
+
+    // Creates an OpenID token, which can be used to prove that a user has access to an account (primarily for integrations)
+    fn create_openid_token(&self, user_id: &UserId) -> Result<(String, u64)>;
+
+    /// Find out which user an OpenID access token belongs to.
+    fn find_from_openid_token(&self, token: &str) -> Result<Option<OwnedUserId>>;
 }
diff --git a/src/service/users/mod.rs b/src/service/users/mod.rs
index 91331667..c3799586 100644
--- a/src/service/users/mod.rs
+++ b/src/service/users/mod.rs
@@ -598,6 +598,16 @@ impl Service {
     ) -> Result<Option<FilterDefinition>> {
         self.db.get_filter(user_id, filter_id)
     }
+
+    // Creates an OpenID token, which can be used to prove that a user has access to an account (primarily for integrations)
+    pub fn create_openid_token(&self, user_id: &UserId) -> Result<(String, u64)> {
+        self.db.create_openid_token(user_id)
+    }
+
+    /// Find out which user an OpenID access token belongs to.
+    pub fn find_from_openid_token(&self, token: &str) -> Result<Option<OwnedUserId>> {
+        self.db.find_from_openid_token(token)
+    }
 }
 
 /// Ensure that a user only sees signatures from themselves and the target user