diff --git a/matrixgw_backend/src/controllers/auth_controller.rs b/matrixgw_backend/src/controllers/auth_controller.rs
index 6cbab4c..42d759f 100644
--- a/matrixgw_backend/src/controllers/auth_controller.rs
+++ b/matrixgw_backend/src/controllers/auth_controller.rs
@@ -1,8 +1,9 @@
 use crate::app_config::AppConfig;
 use crate::controllers::{HttpFailure, HttpResult};
 use crate::extractors::auth_extractor::{AuthExtractor, AuthenticatedMethod};
+use crate::extractors::matrix_client_extractor::MatrixClientExtractor;
 use crate::extractors::session_extractor::MatrixGWSession;
-use crate::users::{ExtendedUserInfo, User, UserEmail};
+use crate::users::{User, UserEmail};
 use actix_remote_ip::RemoteIP;
 use actix_web::{HttpResponse, web};
 use light_openid::primitives::OpenIDConfig;
@@ -107,8 +108,8 @@ pub async fn finish_oidc(
 }
 
 /// Get current user information
-pub async fn auth_info(auth: AuthExtractor) -> HttpResult {
-    Ok(HttpResponse::Ok().json(ExtendedUserInfo::from_user(auth.user).await?))
+pub async fn auth_info(client: MatrixClientExtractor) -> HttpResult {
+    Ok(HttpResponse::Ok().json(client.to_extended_user_info().await?))
 }
 
 /// Sign out user
diff --git a/matrixgw_backend/src/controllers/matrix_link_controller.rs b/matrixgw_backend/src/controllers/matrix_link_controller.rs
index 38fea49..084597a 100644
--- a/matrixgw_backend/src/controllers/matrix_link_controller.rs
+++ b/matrixgw_backend/src/controllers/matrix_link_controller.rs
@@ -1,6 +1,8 @@
 use crate::controllers::HttpResult;
 use crate::extractors::matrix_client_extractor::MatrixClientExtractor;
+use crate::matrix_connection::matrix_client::FinishMatrixAuth;
 use actix_web::HttpResponse;
+use anyhow::Context;
 
 #[derive(serde::Serialize)]
 struct StartAuthResponse {
@@ -12,3 +14,13 @@ pub async fn start_auth(client: MatrixClientExtractor) -> HttpResult {
     let url = client.client.initiate_login().await?.to_string();
     Ok(HttpResponse::Ok().json(StartAuthResponse { url }))
 }
+
+/// Finish user authentication on Matrix server
+pub async fn finish_auth(client: MatrixClientExtractor) -> HttpResult {
+    client
+        .client
+        .finish_login(client.auth.decode_json_body::<FinishMatrixAuth>()?)
+        .await
+        .context("Failed to finalize Matrix authentication!")?;
+    Ok(HttpResponse::Accepted().finish())
+}
diff --git a/matrixgw_backend/src/controllers/mod.rs b/matrixgw_backend/src/controllers/mod.rs
index 8a581e9..8ddf218 100644
--- a/matrixgw_backend/src/controllers/mod.rs
+++ b/matrixgw_backend/src/controllers/mod.rs
@@ -28,7 +28,9 @@ impl ResponseError for HttpFailure {
     }
 
     fn error_response(&self) -> HttpResponse {
-        HttpResponse::build(self.status_code()).body(self.to_string())
+        HttpResponse::build(self.status_code())
+            .content_type("text/plain")
+            .body(self.to_string())
     }
 }
 
diff --git a/matrixgw_backend/src/extractors/auth_extractor.rs b/matrixgw_backend/src/extractors/auth_extractor.rs
index 8c75a29..36003e6 100644
--- a/matrixgw_backend/src/extractors/auth_extractor.rs
+++ b/matrixgw_backend/src/extractors/auth_extractor.rs
@@ -11,6 +11,8 @@ use anyhow::Context;
 use bytes::Bytes;
 use jwt_simple::common::VerificationOptions;
 use jwt_simple::prelude::{Duration, HS256Key, MACLike};
+use jwt_simple::reexports::serde_json;
+use serde::de::DeserializeOwned;
 use sha2::{Digest, Sha256};
 use std::fmt::Display;
 use std::net::IpAddr;
@@ -32,6 +34,16 @@ pub struct AuthExtractor {
     pub payload: Option<Vec<u8>>,
 }
 
+impl AuthExtractor {
+    pub fn decode_json_body<E: DeserializeOwned + Send>(&self) -> anyhow::Result<E> {
+        let payload = self
+            .payload
+            .as_ref()
+            .context("Failed to decode request as json: missing payload!")?;
+        serde_json::from_slice(payload).context("Failed to decode request json!")
+    }
+}
+
 #[derive(Debug, Eq, PartialEq)]
 pub struct MatrixJWTKID {
     pub user_email: UserEmail,
diff --git a/matrixgw_backend/src/extractors/matrix_client_extractor.rs b/matrixgw_backend/src/extractors/matrix_client_extractor.rs
index fbe6d3c..5de4f7f 100644
--- a/matrixgw_backend/src/extractors/matrix_client_extractor.rs
+++ b/matrixgw_backend/src/extractors/matrix_client_extractor.rs
@@ -1,6 +1,7 @@
 use crate::extractors::auth_extractor::AuthExtractor;
 use crate::matrix_connection::matrix_client::MatrixClient;
 use crate::matrix_connection::matrix_manager::MatrixManagerMsg;
+use crate::users::ExtendedUserInfo;
 use actix_web::dev::Payload;
 use actix_web::{FromRequest, HttpRequest, web};
 use ractor::ActorRef;
@@ -10,6 +11,16 @@ pub struct MatrixClientExtractor {
     pub client: MatrixClient,
 }
 
+impl MatrixClientExtractor {
+    pub async fn to_extended_user_info(&self) -> anyhow::Result<ExtendedUserInfo> {
+        Ok(ExtendedUserInfo {
+            user: self.auth.user.clone(),
+            matrix_user_id: self.client.client.user_id().map(|id| id.to_string()),
+            matrix_device_id: self.client.client.device_id().map(|id| id.to_string()),
+        })
+    }
+}
+
 impl FromRequest for MatrixClientExtractor {
     type Error = actix_web::Error;
     type Future = futures_util::future::LocalBoxFuture<'static, Result<Self, Self::Error>>;
diff --git a/matrixgw_backend/src/main.rs b/matrixgw_backend/src/main.rs
index 2571cdc..6c7e4fd 100644
--- a/matrixgw_backend/src/main.rs
+++ b/matrixgw_backend/src/main.rs
@@ -55,7 +55,7 @@ async fn main() -> std::io::Result<()> {
 
         let cors = Cors::default()
             .allowed_origin(&AppConfig::get().website_origin)
-            .allowed_methods(vec!["GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"])
+            .allowed_methods(["GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"])
             .allowed_header(constants::API_AUTH_HEADER)
             .allow_any_header()
             .supports_credentials()
@@ -94,6 +94,10 @@ async fn main() -> std::io::Result<()> {
                 "/api/matrix_link/start_auth",
                 web::post().to(matrix_link_controller::start_auth),
             )
+            .route(
+                "/api/matrix_link/finish_auth",
+                web::post().to(matrix_link_controller::finish_auth),
+            )
     })
     .workers(4)
     .bind(&AppConfig::get().listen_address)?
diff --git a/matrixgw_backend/src/matrix_connection/matrix_client.rs b/matrixgw_backend/src/matrix_connection/matrix_client.rs
index f6dcc86..c6e88cb 100644
--- a/matrixgw_backend/src/matrix_connection/matrix_client.rs
+++ b/matrixgw_backend/src/matrix_connection/matrix_client.rs
@@ -1,8 +1,8 @@
 use crate::app_config::AppConfig;
 use crate::users::UserEmail;
 use crate::utils::rand_utils::rand_string;
-use matrix_sdk::authentication::oauth::OAuthError;
 use matrix_sdk::authentication::oauth::error::OAuthDiscoveryError;
+use matrix_sdk::authentication::oauth::{OAuthError, UrlOrQuery};
 use matrix_sdk::ruma::serde::Raw;
 use matrix_sdk::{Client, ClientBuildError};
 use url::Url;
@@ -28,6 +28,14 @@ enum MatrixClientError {
     ParseAuthRedirectURL(url::ParseError),
     #[error("Failed to build auth request! {0}")]
     BuildAuthRequest(OAuthError),
+    #[error("Failed to finalize authentication! {0}")]
+    FinishLogin(matrix_sdk::Error),
+}
+
+#[derive(serde::Deserialize)]
+pub struct FinishMatrixAuth {
+    code: String,
+    state: String,
 }
 
 #[derive(Clone)]
@@ -91,7 +99,7 @@ impl MatrixClient {
         todo!()
     }
 
-    /// Initiate oauth authentication
+    /// Initiate OAuth authentication
     pub async fn initiate_login(&self) -> anyhow::Result<Url> {
         let oauth = self.client.oauth();
 
@@ -112,4 +120,23 @@ impl MatrixClient {
 
         Ok(auth.url)
     }
+
+    /// Finish OAuth authentication
+    pub async fn finish_login(&self, info: FinishMatrixAuth) -> anyhow::Result<()> {
+        let oauth = self.client.oauth();
+        oauth
+            .finish_login(UrlOrQuery::Query(format!(
+                "state={}&code={}",
+                info.state, info.code
+            )))
+            .await
+            .map_err(MatrixClientError::FinishLogin)?;
+
+        log::info!(
+            "User successfully authenticated as {}!",
+            self.client.user_id().unwrap()
+        );
+
+        Ok(())
+    }
 }
diff --git a/matrixgw_backend/src/users.rs b/matrixgw_backend/src/users.rs
index aab18ed..7eca242 100644
--- a/matrixgw_backend/src/users.rs
+++ b/matrixgw_backend/src/users.rs
@@ -172,13 +172,5 @@ pub struct ExtendedUserInfo {
     #[serde(flatten)]
     pub user: User,
     pub matrix_user_id: Option<String>,
-}
-
-impl ExtendedUserInfo {
-    pub async fn from_user(user: User) -> anyhow::Result<Self> {
-        Ok(Self {
-            user,
-            matrix_user_id: None, // TODO
-        })
-    }
+    pub matrix_device_id: Option<String>,
 }
diff --git a/matrixgw_frontend/src/App.tsx b/matrixgw_frontend/src/App.tsx
index 9988388..7cd3001 100644
--- a/matrixgw_frontend/src/App.tsx
+++ b/matrixgw_frontend/src/App.tsx
@@ -14,6 +14,7 @@ import { MatrixLinkRoute } from "./routes/MatrixLinkRoute";
 import { NotFoundRoute } from "./routes/NotFoundRoute";
 import { BaseLoginPage } from "./widgets/auth/BaseLoginPage";
 import BaseAuthenticatedPage from "./widgets/dashboard/BaseAuthenticatedPage";
+import { MatrixAuthCallback } from "./routes/MatrixAuthCallback";
 
 interface AuthContext {
   signedIn: boolean;
@@ -39,6 +40,7 @@ export function App(): React.ReactElement {
         <Route path="*" element={<BaseAuthenticatedPage />}>
           <Route path="" element={<HomeRoute />} />
           <Route path="matrix_link" element={<MatrixLinkRoute />} />
+          <Route path="matrix_auth_cb" element={<MatrixAuthCallback />} />
           <Route path="*" element={<NotFoundRoute />} />
         </Route>
       ) : (
diff --git a/matrixgw_frontend/src/api/AuthApi.ts b/matrixgw_frontend/src/api/AuthApi.ts
index c0fc286..e2e10ac 100644
--- a/matrixgw_frontend/src/api/AuthApi.ts
+++ b/matrixgw_frontend/src/api/AuthApi.ts
@@ -7,6 +7,7 @@ export interface UserInfo {
   name: string;
   email: string;
   matrix_user_id?: string;
+  matrix_device_id?: string;
 }
 
 const TokenStateKey = "auth-state";
diff --git a/matrixgw_frontend/src/api/MatrixLinkApi.ts b/matrixgw_frontend/src/api/MatrixLinkApi.ts
index 6a05a3c..3796189 100644
--- a/matrixgw_frontend/src/api/MatrixLinkApi.ts
+++ b/matrixgw_frontend/src/api/MatrixLinkApi.ts
@@ -12,4 +12,15 @@ export class MatrixLinkApi {
       })
     ).data;
   }
+
+  /**
+   * Finish Matrix Account login
+   */
+  static async FinishAuth(code: string, state: string): Promise<void> {
+    await APIClient.exec({
+      uri: "/matrix_link/finish_auth",
+      method: "POST",
+      jsonData: { code, state },
+    });
+  }
 }
diff --git a/matrixgw_frontend/src/routes/MatrixAuthCallback.tsx b/matrixgw_frontend/src/routes/MatrixAuthCallback.tsx
new file mode 100644
index 0000000..ae9906c
--- /dev/null
+++ b/matrixgw_frontend/src/routes/MatrixAuthCallback.tsx
@@ -0,0 +1,79 @@
+import { Alert, Box, Button, CircularProgress } from "@mui/material";
+import React from "react";
+import { useNavigate, useSearchParams } from "react-router";
+import { MatrixLinkApi } from "../api/MatrixLinkApi";
+import { useUserInfo } from "../widgets/dashboard/BaseAuthenticatedPage";
+import { RouterLink } from "../widgets/RouterLink";
+import { useSnackbar } from "../hooks/contexts_provider/SnackbarProvider";
+
+export function MatrixAuthCallback(): React.ReactElement {
+  const navigate = useNavigate();
+  const snackbar = useSnackbar();
+
+  const info = useUserInfo();
+
+  const [error, setError] = React.useState<null | string>(null);
+
+  const [searchParams] = useSearchParams();
+  const code = searchParams.get("code");
+  const state = searchParams.get("state");
+
+  const count = React.useRef("");
+
+  React.useEffect(() => {
+    const load = async () => {
+      try {
+        if (count.current === code) {
+          return;
+        }
+        count.current = code!;
+
+        await MatrixLinkApi.FinishAuth(code!, state!);
+        info.reloadUserInfo();
+        snackbar("Successfully linked to Matrix account!");
+        navigate("/matrix_link");
+      } catch (e) {
+        console.error(e);
+        setError(String(e));
+      }
+    };
+
+    load();
+  });
+
+  if (error)
+    return (
+      <Box
+        component="div"
+        sx={{
+          display: "flex",
+          justifyContent: "center",
+          alignItems: "center",
+          height: "100%",
+          flex: "1",
+          flexDirection: "column",
+        }}
+      >
+        <Alert
+          variant="outlined"
+          severity="error"
+          style={{ margin: "0px 15px 15px 15px" }}
+        >
+          Failed to finalize Matrix authentication!
+          <br />
+          <br />
+          {error}
+        </Alert>
+
+        <Button>
+          <RouterLink to="/matrix_link">Go back</RouterLink>
+        </Button>
+      </Box>
+    );
+
+  return (
+    <div style={{ textAlign: "center" }}>
+      <CircularProgress />
+    </div>
+  );
+}
diff --git a/matrixgw_frontend/src/routes/MatrixLinkRoute.tsx b/matrixgw_frontend/src/routes/MatrixLinkRoute.tsx
index 7a33ed7..23a3b27 100644
--- a/matrixgw_frontend/src/routes/MatrixLinkRoute.tsx
+++ b/matrixgw_frontend/src/routes/MatrixLinkRoute.tsx
@@ -79,9 +79,17 @@ function ConnectedCard(): React.ReactElement {
 
         <Typography variant="body1" gutterBottom>
           <p>
-            MatrixGW is currently connected to your account with ID{" "}
-            <i>{user.info.matrix_user_id}</i>.
+            MatrixGW is currently connected to your account with the following
+            information:
           </p>
+          <ul>
+            <li>
+              User id: <i>{user.info.matrix_user_id}</i>
+            </li>
+            <li>
+              Device id: <i>{user.info.matrix_device_id}</i>
+            </li>
+          </ul>
           <p>
             If you encounter issues with your Matrix account you can try to
             disconnect and connect back again.