Send form submissions to Slack

A channel that lights up with each new lead or support request is one of the most useful things to wire to a form. This guide posts each Ikiform submission to Slack as a tidy message with one line per field.

Why there's a relay

Slack's incoming webhooks accept a message shaped as { "text": ... } or { "blocks": [...] }. Ikiform sends a submission event shaped as { "type": ..., "data": ... }, and Slack answers that with 400 no_text.

The relay is about 60 lines. It also keeps the Slack URL private, and it checks Ikiform's signature, so nobody else can post to your channel through it. If you'd rather not deploy code, use n8n, Zapier or Make with their Slack actions.

Before you start

• An Ikiform form that already receives submissions.
• Permission to add apps to your Slack workspace.
• Somewhere to run the relay: a Cloudflare account with a domain on it, or a Next.js app on Vercel or any other host.

What Ikiform sends

Every delivery is a POST with a JSON body. The body has the same shape for every endpoint, and you can't change it. A submission looks like this:

{
  "id": "dlv_01k7v2d4n8r2p6s0w3y5b7c9e1",
  "type": "submission.created",
  "timestamp": "2026-10-23T12:00:00.000Z",
  "api_version": "2026-10-17",
  "data": {
    "submission_id": "sub_01k7v2c9t3e8m5q4x6z0a1b2c3",
    "form": { "id": "frm_xxxxxxxxxxxxxxxx", "name": "Contact" },
    "fields": { "name": "Ada", "email": "ada@example.com", "message": "Hello" },
    "meta": {
      "user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)",
      "origin": "https://example.com",
      "referrer": "https://example.com/contact",
      "country": "GB",
      "subject": null,
      "reply_to": "ada@example.com"
    },
    "created_at": "2026-10-23T12:00:00.000Z",
    "truncated": false
  }
}

The form's values are in data.fields, keyed by the input name. A test from the dashboard sends an endpoint.test event instead, with data.endpoint_id and data.message and no fields. The full reference is on Webhooks.

Set it up

1. Create a Slack incoming webhook

   1. Go to api.slack.com/apps, choose Create New App, then From scratch. Name it, for example Ikiform, and pick your workspace.
   2. Open Incoming Webhooks in the app's settings and turn on Activate Incoming Webhooks.
   3. Choose Add New Webhook to Workspace, pick the channel, and confirm.
   4. Copy the webhook URL. It looks like https://hooks.slack.com/services/T000/B000/XXXX.

   Check it works before going further:

   curl -X POST "$SLACK_WEBHOOK_URL" \
     -H "Content-Type: application/json" \
     -d '{"text":"Hello from the terminal"}'

   Slack answers ok and the message shows up in the channel. Treat the URL as a secret: anyone who has it can post to that channel, and Slack revokes URLs it finds in public code.

2. Write the relay

   Pick the platform you already use. Both versions verify the signature with @ikiform/sdk, format the message, and turn Slack errors into answers Ikiform retries.

   Cloudflare WorkerNext.js

   src/index.ts

   import { verifyWebhook, type WebhookEvent, WebhookVerificationError } from "@ikiform/sdk/webhooks";
   
   interface Env {
     IKIFORM_WEBHOOK_SECRET: string;
     SLACK_WEBHOOK_URL: string;
   }
   
   function valueText(value: unknown): string {
     if (value === null || value === undefined || value === "") return "(empty)";
     if (Array.isArray(value)) return value.map(valueText).join(", ");
     if (typeof value === "object") return JSON.stringify(value);
     return String(value);
   }
   
   function escape(text: string) {
     return text.replaceAll("&", "&amp;").replaceAll("<", "&lt;").replaceAll(">", "&gt;");
   }
   
   function clip(text: string, max: number) {
     return text.length > max ? `${text.slice(0, max - 1)}…` : text;
   }
   
   function toSlack(event: WebhookEvent) {
     if (event.type === "endpoint.test") return { text: "Ikiform test event received. Submissions will appear here." };
     const { form, fields, submission_id, truncated } = event.data;
     const lines = Object.entries(fields)
       .slice(0, 40)
       .map(([name, value]) => clip(`*${escape(name)}*\n${escape(valueText(value))}`, 2000));
     const sections = Array.from({ length: Math.ceil(lines.length / 10) }, (_, index) => ({
       type: "section",
       fields: lines.slice(index * 10, index * 10 + 10).map((text) => ({ type: "mrkdwn", text })),
     }));
     const note = truncated ? "Too large to show here. Open it in Ikiform." : `\`${submission_id}\``;
     return {
       text: `New submission on ${escape(form.name)}`,
       blocks: [
         { type: "header", text: { type: "plain_text", text: clip(`New submission: ${form.name}`, 150) } },
         ...sections,
         { type: "context", elements: [{ type: "mrkdwn", text: note }] },
       ],
     };
   }
   
   export default {
     async fetch(request: Request, env: Env) {
       if (request.method !== "POST") return new Response(null, { status: 405 });
       const payload = await request.text();
       let event: WebhookEvent;
       try {
         event = await verifyWebhook({ payload, headers: request.headers, secret: env.IKIFORM_WEBHOOK_SECRET });
       } catch (error) {
         if (error instanceof WebhookVerificationError) return new Response(error.reason, { status: 400 });
         throw error;
       }
       const response = await fetch(env.SLACK_WEBHOOK_URL, {
         method: "POST",
         headers: { "content-type": "application/json" },
         body: JSON.stringify(toSlack(event)),
       });
       if (response.status === 429) {
         const retryAfter = response.headers.get("retry-after") ?? "30";
         return new Response("Slack rate limit", { status: 503, headers: { "retry-after": retryAfter } });
       }
       if (!response.ok) return new Response(`Slack answered ${response.status}`, { status: 502 });
       return new Response(null, { status: 204 });
     },
   };

   1. form.name: Contact becomes header: New submission: Contact.
   2. fields.name: Ada becomes section field: name / Ada.
   3. fields.email: ada@example.com becomes section field: email / ada@example.com.
   4. fields.message: Hello becomes section field: message / Hello.
   5. submission_id becomes context: sub_… id.

   For the sample submission above, the relay posts this to Slack:

   {
     "text": "New submission on Contact",
     "blocks": [
       { "type": "header", "text": { "type": "plain_text", "text": "New submission: Contact" } },
       {
         "type": "section",
         "fields": [
           { "type": "mrkdwn", "text": "*name*\nAda" },
           { "type": "mrkdwn", "text": "*email*\nada@example.com" },
           { "type": "mrkdwn", "text": "*message*\nHello" }
         ]
       },
       { "type": "context", "elements": [{ "type": "mrkdwn", "text": "`sub_01k7v2c9t3e8m5q4x6z0a1b2c3`" }] }
     ]
   }

   • Slack's limits are 10 fields per section and 2,000 characters per field, so long values are cut and the fields split across sections.
   • &, < and > are escaped, so a visitor can't inject links or mentions.
   • A 429 from Slack becomes a 503 with the same Retry-After, so Ikiform waits before it tries again. Any other Slack error becomes a 502, which Ikiform retries.

3. Deploy it

   Cloudflare Worker

   mkdir ikiform-slack && cd ikiform-slack
   npm init -y
   npm install @ikiform/sdk
   npm install -D wrangler

   Save the Worker code as src/index.ts, then set the route in wrangler.jsonc:

   {
     "$schema": "node_modules/wrangler/config-schema.json",
     "name": "ikiform-slack",
     "main": "src/index.ts",
     "compatibility_date": "2026-10-01",
     "routes": [{ "pattern": "hooks.example.com", "custom_domain": true }]
   }

   Ikiform refuses workers.dev URLs, so the Worker needs a hostname on a domain you have on Cloudflare, like hooks.example.com. The custom_domain route creates the DNS record and certificate for you on deploy.

   Add both secrets and deploy:

   npx wrangler secret put IKIFORM_WEBHOOK_SECRET
   npx wrangler secret put SLACK_WEBHOOK_URL
   npx wrangler deploy

   Your relay URL is https://hooks.example.com/.

   Next.js

   Add @ikiform/sdk to the app, save the route handler, and set IKIFORM_WEBHOOK_SECRET and SLACK_WEBHOOK_URL in your host's environment variables. On Vercel the relay URL is https://your-app.vercel.app/api/ikiform/slack. Use the production domain: Vercel's deployment protection blocks requests to protected preview URLs.

4. Add the endpoint in Ikiform

   • In the Ikiform dashboard, open Webhooks and choose Add endpoint.
   • Paste your relay URL into URL.
   • Under Forms, pick one form, or All forms in the workspace.
   • Add a Description if you like, such as "Slack #leads", then choose Add endpoint.
   • Copy the signing secret. It starts with whsec_ and is shown in full only once.

   There's no event picker. An endpoint gets submission.created for every accepted submission on the forms you chose, and endpoint.test when you send a test. A workspace on Pro can have up to 3 endpoints.

5. Add the secret to the relay

   Set IKIFORM_WEBHOOK_SECRET to the whsec_ secret. On Cloudflare run npx wrangler secret put IKIFORM_WEBHOOK_SECRET again; it takes effect right away. On Vercel, update the variable and redeploy.

Ikiform only delivers to public https:// URLs on port 443. IP addresses, localhost, internal hostnames, workers.dev and pages.dev are refused when you save the endpoint.

Test it

Open the endpoint in Ikiform and choose Send test. Ikiform sends one endpoint.test event with no retries, and the result shows up in the endpoint's delivery log within a few seconds. Then send a real submission from your form, or from a terminal:

curl https://ikiform.com/f/frm_xxxxxxxxxxxxxxxx \
  -H "Content-Type: application/json" \
  -d '{"name":"Ada","email":"ada@example.com","message":"Hello from curl"}'

A 201 with "ok": true means Ikiform stored it. The delivery appears on the endpoint page, and the message lands in Slack.

The test event posts a short line to the channel. A real submission posts the full message, with the submission id at the bottom.

How delivery works

Failed deliveries are retried 8 times over about 3 d 6 h, with the same webhook-id each time. If every delivery to an endpoint fails for 5 days, Ikiform disables it and emails the workspace owners.

Slack allows about one message per second per webhook. A burst of submissions can hit that, and the relay passes Slack's Retry-After back to Ikiform, so the extra messages arrive a little later rather than not at all.

Troubleshooting

Next steps

• Send each form to its own channel: add one Slack webhook per channel and one Ikiform endpoint per form. Pro allows 3 endpoints.
• Add a button that links to the submission in your own admin, using data.submission_id.
• Skip duplicates by storing the webhook-id header, as in Receiving webhooks.