diff --git a/chat/src/http/ws/mod.rs b/chat/src/http/ws/mod.rs
index a3557e1..e38eb4c 100644
--- a/chat/src/http/ws/mod.rs
+++ b/chat/src/http/ws/mod.rs
@@ -1,4 +1,4 @@
-use std::sync::Arc;
+use std::{sync::Arc, time::Duration};
 
 use axum::{
     extract::{
@@ -8,8 +8,9 @@ use axum::{
     response::Response,
     Extension,
 };
-use eyre::{eyre, Error, Result};
+use eyre::{eyre, Result};
 use foxchat::{
+    model::User,
     s2s::{Dispatch, Payload},
     signature::{parse_date, verify_signature},
 };
@@ -17,7 +18,11 @@ use futures::{
     stream::{SplitSink, SplitStream, StreamExt},
     SinkExt,
 };
-use tokio::sync::{broadcast, mpsc, RwLock};
+use rand::Rng;
+use tokio::{
+    sync::{broadcast, mpsc, RwLock},
+    time::timeout,
+};
 use tracing::error;
 
 use crate::{app_state::AppState, model::identity_instance::IdentityInstance};
@@ -28,6 +33,7 @@ pub async fn handler(ws: WebSocketUpgrade, Extension(state): Extension<Arc<AppSt
 
 struct SocketState {
     instance: Option<IdentityInstance>,
+    last_heartbeat: u64,
 }
 
 async fn handle_socket(app_state: Arc<AppState>, socket: WebSocket) {
@@ -36,16 +42,21 @@ async fn handle_socket(app_state: Arc<AppState>, socket: WebSocket) {
     let (tx, rx) = mpsc::channel::<Payload>(10);
     let dispatch = app_state.broadcast.subscribe();
     let socket_state = Arc::new(RwLock::new(SocketState {
-        instance: None, // Filled out after IDENTIFY
+        // These are filled out after IDENTIFY
+        instance: None,
+        last_heartbeat: 0,
     }));
 
+    // Function that merges the socket-local and broadcast streams for sending.
     tokio::spawn(merge_channels(
         app_state.clone(),
         socket_state.clone(),
         dispatch,
         tx.clone(),
     ));
+    // Function that writes all payloads to the socket.
     tokio::spawn(write(rx, sender));
+    // Function that reads from the socket.
     tokio::spawn(read(
         app_state.clone(),
         socket_state.clone(),
@@ -71,7 +82,8 @@ async fn read(
                         server,
                         signature,
                     } => {
-                        let instance = match IdentityInstance::get(app_state, &server).await {
+                        let instance = match IdentityInstance::get(app_state.clone(), &server).await
+                        {
                             Ok(i) => i,
                             Err(e) => {
                                 error!("getting instance {}: {}", server, e);
@@ -161,8 +173,17 @@ async fn read(
         return;
     }
 
-    // Send hello
-    tx.send(Payload::Hello {}).await.ok();
+    // Generate heartbeat interval and send it in the Hello payload
+    let heartbeat_interval = rand::thread_rng().gen_range(45_000..70_000);
+    tx.send(Payload::Hello { heartbeat_interval }).await.ok();
+    // Start the heartbeat loop
+    let (heartbeat_tx, heartbeat_rx) = mpsc::channel::<u64>(10);
+    tokio::spawn(heartbeat(
+        socket_state.clone(),
+        heartbeat_interval,
+        heartbeat_rx,
+        tx.clone(),
+    ));
 
     while let Some(msg) = receiver.next().await {
         let Ok(msg) = msg else {
@@ -188,13 +209,69 @@ async fn read(
         };
 
         match msg {
-            Payload::Connect { user_id } => {}
+            Payload::Connect { user_id } => {
+                match collect_ready(app_state.clone(), socket_state.clone(), &user_id).await {
+                    Ok(p) => {
+                        tx.send(p).await.ok();
+                    }
+                    Err(e) => {
+                        error!("Error collecting ready event data for {}: {}", user_id, e);
+                        tx.send(Payload::Error {
+                            message: "Internal server error".into(),
+                        })
+                        .await
+                        .ok();
+                    }
+                }
+            }
+            Payload::Heartbeat { timestamp } => {
+                // Heartbeats are handled in another function
+                heartbeat_tx.send(timestamp).await.ok();
+            }
+            _ => {
+                tx.send(Payload::Error {
+                    message: "Invalid send event".into(),
+                })
+                .await
+                .ok();
+                return;
+            }
         }
-
-        // TODO: handle incoming payloads
     }
 }
 
+async fn heartbeat(
+    socket_state: Arc<RwLock<SocketState>>,
+    heartbeat_interval: u64,
+    mut rx: mpsc::Receiver<u64>,
+    tx: mpsc::Sender<Payload>,
+) {
+    // The timeout is twice the heartbeat interval. If no heartbeat is received by then, close the connection with an error.
+    while let Ok(i) = timeout(Duration::from_millis(heartbeat_interval * 2), rx.recv()).await {
+        match i {
+            // ACK the heartbeat with the same timestamp. TODO: validate the timestamp to make sure we aren't too out of sync with the identity server.
+            Some(timestamp) => {
+                socket_state.write().await.last_heartbeat = timestamp;
+                tx.send(Payload::HeartbeatAck { timestamp }).await.ok();
+            }
+            // If the channel returns None, that means it's been closed, which means the socket as a whole was closed
+            None => {
+                return;
+            }
+        };
+    }
+
+    // Send an error, which will automatically close the socket
+    tx.send(Payload::Error {
+        message: format!(
+            "Did not receive a heartbeat after {}ms",
+            heartbeat_interval * 2
+        ),
+    })
+    .await
+    .ok();
+}
+
 async fn write(mut rx: mpsc::Receiver<Payload>, mut sender: SplitSink<WebSocket, Message>) {
     loop {
         if let Some(ev) = rx.recv().await {
@@ -355,19 +432,32 @@ async fn filter_events(
 async fn collect_ready(
     app_state: Arc<AppState>,
     socket_state: Arc<RwLock<SocketState>>,
-    user_id: String,
+    user_id: &str,
 ) -> Result<Payload> {
     let Some(instance) = &socket_state.read().await.instance else {
         return Err(eyre!("instance was None when it shouldn't be"));
     };
 
     let user = sqlx::query!(
-        "SELECT * FROM users WHERE instance_id = $1 AND remote_user_id = $2",
+        r#"SELECT u.*, i.domain FROM users u
+        JOIN identity_instances i ON i.id = u.instance_id
+        WHERE u.instance_id = $1 AND u.remote_user_id = $2"#,
         instance.id,
         user_id
     )
     .fetch_one(&app_state.pool)
     .await?;
 
-    todo!()
+    Ok(Payload::Dispatch {
+        event: Dispatch::Ready {
+            user: User {
+                id: user.id,
+                username: user.username,
+                instance: user.domain,
+                avatar_url: None,
+            },
+            guilds: vec![],
+        },
+        recipients: vec![user.remote_user_id],
+    })
 }
diff --git a/foxchat/src/s2s/event.rs b/foxchat/src/s2s/event.rs
index 110269c..fb866a6 100644
--- a/foxchat/src/s2s/event.rs
+++ b/foxchat/src/s2s/event.rs
@@ -5,6 +5,7 @@ use super::Dispatch;
 #[derive(Debug, Serialize, Deserialize)]
 #[serde(tag = "t", content = "d", rename_all = "SCREAMING_SNAKE_CASE")]
 pub enum Payload {
+    #[serde(rename = "D")]
     Dispatch {
         #[serde(rename = "e")]
         event: Dispatch,
@@ -15,7 +16,9 @@ pub enum Payload {
         message: String,
     },
     /// Hello message, sent after authentication succeeds
-    Hello {},
+    Hello {
+        heartbeat_interval: u64,
+    },
     /// S2S authentication. Fields correspond to headers (Host, Date, X-Foxchat-Server, X-Foxchat-Signature)
     Identify {
         host: String,
@@ -26,5 +29,15 @@ pub enum Payload {
     /// Sent when a user connects to the identity server's gateway, to signal the chat server to send READY for that user
     Connect {
         user_id: String,
+    },
+    /// Sent on a regular interval by the connecting server, to keep the connection alive.
+    Heartbeat {
+        #[serde(rename = "t")]
+        timestamp: u64,
+    },
+    /// Sent in response to a Heartbeat.
+    HeartbeatAck {
+        #[serde(rename = "t")]
+        timestamp: u64,
     }
 }