HMAC-SHA256 · hex · no timestamp

Linear

Linear signs like GitHub but ships the digest bare, with no sha256= prefix.

Try it, live in your browser

import { verify } from "hooksig";

const result = await verify("linear", {
  payload: rawBody,            // the RAW body, not parsed JSON
  headers: request.headers,
  secret: env.WEBHOOK_SECRET,
});

if (!result.verified) {
  return new Response(result.reason, { status: 400 });
}

The scheme

• HeaderLinear-Signature
• AlgorithmHMAC-SHA256
• Encodinghex
• Timestampnone, add your own if you need it
• SignsHMAC-SHA256 over the raw body, hex-encoded, bare digest with no prefix, keyed by the webhook signing secret. No timestamp.

Gotchas

• The header is the bare hex digest, with no sha256= prefix.
• The key is the webhook signing secret from the Linear settings, used verbatim.
• Sign the RAW body. Re-stringified JSON changes bytes and every check fails.
• Linear also puts a timestamp in the JSON payload; verify it against your tolerance yourself, since it is not folded into the signature.

Official Linear docs →