diff --git a/src/worker.ts b/src/worker.ts
new file mode 100644
index 0000000..2632091
--- /dev/null
+++ b/src/worker.ts
@@ -0,0 +1,167 @@
+type Env = {
+    TURNSTILE_SECRET_KEY?: string;
+    AZURE_COMMUNICATION_CONNECTION_STRING?: string;
+    CONTACT_FROM_EMAIL?: string;
+    CONTACT_TO_EMAIL?: string;
+    ASSETS: Fetcher;
+};
+
+const jsonResponse = (data: Record<string, unknown>, status = 200) =>
+    new Response(JSON.stringify(data), {
+        status,
+        headers: { "content-type": "application/json" },
+    });
+
+const readFormField = (value: FormDataEntryValue | null) =>
+    typeof value === "string" ? value.trim() : "";
+
+const parseConnectionString = (connectionString: string) => {
+    const parts = connectionString.split(";").filter(Boolean);
+    const map = new Map<string, string>();
+    for (const part of parts) {
+        const [rawKey, ...rest] = part.split("=");
+        const key = rawKey?.trim().toLowerCase();
+        const value = rest.join("=").trim();
+        if (key && value) {
+            map.set(key, value);
+        }
+    }
+    return {
+        endpoint: map.get("endpoint") ?? "",
+        accessKey: map.get("accesskey") ?? map.get("access_key") ?? "",
+    };
+};
+
+const handleContact = async (request: Request, env: Env) => {
+    const formData = await request.formData();
+    const name = readFormField(formData.get("name"));
+    const email = readFormField(formData.get("email"));
+    const message = readFormField(formData.get("message"));
+    const turnstileToken = readFormField(
+        formData.get("cf-turnstile-response"),
+    );
+
+    if (!name || !email || !message) {
+        return jsonResponse({ ok: false, error: "Missing required fields." }, 400);
+    }
+
+    if (!env.TURNSTILE_SECRET_KEY) {
+        return jsonResponse(
+            { ok: false, error: "Turnstile secret key not configured." },
+            500,
+        );
+    }
+
+    if (!turnstileToken) {
+        return jsonResponse(
+            { ok: false, error: "Turnstile verification failed." },
+            400,
+        );
+    }
+
+    const verifyBody = new URLSearchParams({
+        secret: env.TURNSTILE_SECRET_KEY,
+        response: turnstileToken,
+        remoteip: request.headers.get("CF-Connecting-IP") ?? "",
+    });
+
+    const verifyResponse = await fetch(
+        "https://challenges.cloudflare.com/turnstile/v0/siteverify",
+        {
+            method: "POST",
+            body: verifyBody,
+        },
+    );
+    const verifyResult = (await verifyResponse.json()) as {
+        success?: boolean;
+    };
+
+    if (!verifyResult.success) {
+        return jsonResponse(
+            { ok: false, error: "Turnstile verification failed." },
+            400,
+        );
+    }
+
+    if (!env.AZURE_COMMUNICATION_CONNECTION_STRING) {
+        return jsonResponse(
+            { ok: false, error: "Email provider not configured." },
+            500,
+        );
+    }
+
+    const fromEmail = env.CONTACT_FROM_EMAIL;
+    if (!fromEmail) {
+        return jsonResponse(
+            { ok: false, error: "Sender email not configured." },
+            500,
+        );
+    }
+
+    const toEmail = env.CONTACT_TO_EMAIL ?? "calum@muir.in";
+    const { endpoint, accessKey } = parseConnectionString(
+        env.AZURE_COMMUNICATION_CONNECTION_STRING,
+    );
+    if (!endpoint || !accessKey) {
+        return jsonResponse(
+            { ok: false, error: "Email provider not configured." },
+            500,
+        );
+    }
+
+    const emailPayload = {
+        senderAddress: fromEmail,
+        content: {
+            subject: "New contact form submission",
+            plainText: `Name: ${name}\nEmail: ${email}\n\n${message}`,
+        },
+        recipients: {
+            to: [{ address: toEmail }],
+        },
+        replyTo: [{ address: email }],
+    };
+
+    const response = await fetch(
+        `${endpoint.replace(/\\/$/, "")}/emails:send?api-version=2023-03-31`,
+        {
+            method: "POST",
+            headers: {
+                "Content-Type": "application/json",
+                "api-key": accessKey,
+            },
+            body: JSON.stringify(emailPayload),
+        },
+    );
+    if (!response.ok) {
+        const errorText = await response.text();
+        return jsonResponse(
+            {
+                ok: false,
+                error: "Failed to send email.",
+                details: errorText.slice(0, 500),
+            },
+            502,
+        );
+    }
+
+    return jsonResponse({ ok: true });
+};
+
+export default {
+    async fetch(request: Request, env: Env): Promise<Response> {
+        const url = new URL(request.url);
+        if (url.pathname === "/api/contact") {
+            if (request.method !== "POST") {
+                return jsonResponse(
+                    { ok: false, error: "Method not allowed." },
+                    405,
+                );
+            }
+            return handleContact(request, env);
+        }
+        if (env.ASSETS?.fetch) {
+            return env.ASSETS.fetch(request);
+        }
+        return new Response("Not found", { status: 404 });
+    },
+};
diff --git a/wrangler.jsonc b/wrangler.jsonc
index cb4eb22..66b36cb 100644
--- a/wrangler.jsonc
+++ b/wrangler.jsonc
@@ -1,8 +1,10 @@
 {
     "name": "rda-2026",
+    "main": "src/worker.ts",
     "compatibility_date": "2025-12-21",
     "assets": {
         "directory": "./dist/public",
+        "binding": "ASSETS",
         "not_found_handling": "single-page-application",
     },
 }