diff --git a/client/index.html b/client/index.html
index f4f876b..968cc68 100644
--- a/client/index.html
+++ b/client/index.html
@@ -33,6 +33,9 @@
                     </div>
                 </div>
                 <div id="messages"></div>
+                <div id="roomfooter">
+                    <input id="sendmessageinput" type="text" placeholder="Enter text or commands /me /invite /join /leave" spellcheck="true" />
+                </div>
             </div>
             <template id="roomCellTemplate">
                 <div class="roomcell">
diff --git a/client/index.js b/client/index.js
index e201fad..c1d3301 100644
--- a/client/index.js
+++ b/client/index.js
@@ -11,6 +11,7 @@ import {
 } from "./sync.js";
 import * as render from "./render.js";
 import * as devtools from "./devtools.js";
+import * as matrix from "./matrix.js";
 
 let syncv2ServerUrl; // will be populated with the URL of the CS API e.g 'https://matrix-client.matrix.org'
 let slidingSync;
@@ -428,4 +429,27 @@ window.addEventListener("load", async (event) => {
         // interrupt the sync request to send up new filters
         syncConnection.abort();
     });
+
+    // hook up the send message input
+    document
+        .getElementById("sendmessageinput")
+        .addEventListener("keydown", async (ev) => {
+            if (ev.key == "Enter") {
+                ev.target.setAttribute("disabled", "");
+                const msg = ev.target.value;
+                try {
+                    await matrix.sendMessage(
+                        syncv2ServerUrl,
+                        document.getElementById("accessToken").value,
+                        slidingSync.roomSubscription,
+                        msg
+                    );
+                    ev.target.value = "";
+                } catch (err) {
+                    document.getElementById("errorMsg").textContent =
+                        "Error sending message: " + err;
+                }
+                ev.target.removeAttribute("disabled");
+            }
+        });
 });
diff --git a/client/matrix.js b/client/matrix.js
new file mode 100644
index 0000000..54b4d01
--- /dev/null
+++ b/client/matrix.js
@@ -0,0 +1,106 @@
+/**
+ * This file contains Matrix CS API code. Not relevant for sliding sync, but relevant for general
+ * client code e.g sending events.
+ */
+
+async function doRequest(fullUrl, accessToken, method, body) {
+    const resp = await fetch(fullUrl, {
+        method: method,
+        headers: {
+            Authorization: "Bearer " + accessToken,
+            "Content-Type": "application/json",
+        },
+        body: body ? JSON.stringify(body) : undefined,
+    });
+    if (!resp.ok) {
+        throw new Error("HTTP " + resp.status);
+    }
+    return await resp.json();
+}
+
+async function inviteToRoom(v2serverUrl, accessToken, roomId, userId) {
+    await doRequest(
+        `${v2serverUrl}/_matrix/client/v3/rooms/${encodeURIComponent(
+            roomId
+        )}/invite`,
+        accessToken,
+        "POST",
+        {
+            user_id: userId,
+        }
+    );
+}
+
+async function joinRoom(v2serverUrl, accessToken, roomIdOrAlias) {
+    await doRequest(
+        `${v2serverUrl}/_matrix/client/v3/join/${encodeURIComponent(
+            roomIdOrAlias
+        )}`,
+        accessToken,
+        "POST",
+        {}
+    );
+}
+
+async function leaveRoom(v2serverUrl, accessToken, roomId) {
+    await doRequest(
+        `${v2serverUrl}/_matrix/client/v3/rooms/${encodeURIComponent(
+            roomId
+        )}/leave`,
+        accessToken,
+        "POST",
+        {}
+    );
+}
+
+/**
+ * Send a Matrix event.
+ * @param {string} v2serverUrl The CS API endpoint base URL.
+ * @param {string} accessToken The user's access token.
+ * @param {string} roomId The room to send the event in.
+ * @param {string} rawText The raw text input by the user. The text entered will affect the operation.
+ */
+export async function sendMessage(v2serverUrl, accessToken, roomId, rawText) {
+    rawText = rawText.trim();
+
+    if (rawText.startsWith("/invite ")) {
+        await inviteToRoom(
+            v2serverUrl,
+            accessToken,
+            roomId,
+            rawText.substring("/invite ".length)
+        );
+        return;
+    } else if (rawText.startsWith("/join ")) {
+        await joinRoom(
+            v2serverUrl,
+            accessToken,
+            rawText.substring("/join ".length)
+        );
+        return;
+    } else if (rawText === "/leave") {
+        await leaveRoom(v2serverUrl, accessToken, roomId);
+        return;
+    }
+
+    let jsonBody = {
+        msgtype: "m.text",
+        body: rawText,
+    };
+    if (rawText.startsWith("/me ")) {
+        jsonBody = {
+            msgtype: "m.emote",
+            body: rawText.substring("/me ".length),
+        };
+    }
+    const txnId = "" + new Date().getTime();
+
+    await doRequest(
+        `${v2serverUrl}/_matrix/client/v3/rooms/${encodeURIComponent(
+            roomId
+        )}/send/m.room.message/${txnId}`,
+        accessToken,
+        "PUT",
+        jsonBody
+    );
+}
diff --git a/client/styles.css b/client/styles.css
index 44ae0b3..7718f3a 100644
--- a/client/styles.css
+++ b/client/styles.css
@@ -142,3 +142,11 @@ body {
     border: 1px solid;
     padding: 5px;
 }
+
+#roomfooter {
+    margin: 5px;
+}
+
+#sendmessageinput {
+    width: 100%;
+}