Build on Sign IT

Create an API key under Settings → API, then send it as a bearer token. Keys are shown once and stored hashed — treat them like passwords.

Authorization: Bearer sk_signit_…

The fastest path is a template: capture the layout once in the app, then instantiate it with real recipients. send: true emails everyone in the same call.

POST https://www.signitdigital.com/api/v1/envelopes
Content-Type: application/json

{
  "template_id": "tpl_…",
  "recipients": [{ "name": "Dana Okafor", "email": "dana@example.com" }],
  "send": true
}

You can also post a raw PDF (base64) with explicit field geometry — see the response of GET /api/v1/envelopes/:id for envelope status and signing links.

Register an endpoint under Settings → Webhooks and Sign IT will POST JSON for envelope.completed, envelope.declined and envelope.expired. Every delivery is signed so you can prove it came from us:

X-SignIT-Event: envelope.completed
X-SignIT-Signature: t=1755400000,v1=hex(HMAC-SHA256(secret, t + "." + rawBody))

Verify it in a few lines of Node:

import { createHmac, timingSafeEqual } from "node:crypto";

function verify(rawBody, header, secret) {
  const { t, v1 } = Object.fromEntries(header.split(",").map((p) => p.split("=")));
  const expected = createHmac("sha256", secret).update(`${t}.${rawBody}`).digest("hex");
  return timingSafeEqual(Buffer.from(v1), Buffer.from(expected));
}

Until our listed Zapier app ships, the "Webhooks by Zapier" trigger does the same job: create a Zap with a Catch Hook trigger, paste the hook URL into Settings → Webhooks, and every completed envelope becomes a Zap run — push it to Google Sheets, Slack, HubSpot, QuickBooks, anywhere Zapier reaches.

Any signing link can run inside an iframe on your site — copy the embed code from an envelope's page. When the signer finishes, the frame posts a message so your page can react:

<iframe src="https://www.signitdigital.com/sign/TOKEN?embed=1"
        style="width:100%;height:720px;border:0"></iframe>

<script>
window.addEventListener("message", (e) => {
  if (e.data?.source === "signit" && e.data.event === "completed") {
    // advance your flow
  }
});
</script>