Webhooks, Slack & ZapierPro+

Setting Up Webhooks — Step-by-Step

How to register an endpoint, copy your signing secret, and verify deliveries on your own server.

Step 1 — Register Your Endpoint

The URL must be HTTPS. If you lose your secret, you'll need to remove the endpoint and create a new one — there's no way to reveal it again.

1

Open Settings

In your SMLLR dashboard, click Settings in the left sidebar.

2

Go to the Webhooks & Slack tab

Click the Webhooks & Slack tab at the top of the Settings page.

3

Click Add Endpoint

Choose Generic Webhook, enter your HTTPS URL, pick which events you want, and click Save.

4

Copy your secret immediately

Your signing secret is shown once, right after creation. Copy it now — SMLLR never displays it again.

Step 2 — Verify Deliveries on Your Server

Every delivery includes an X-Smllr-Signature header (sha256=) and an X-Smllr-Timestamp header. Recompute the signature yourself and compare:

See the code sample (Node.js) on the API Documentation page's Webhooks section for a copy-pasteable verification function.

  • Take the raw request body exactly as received — don't re-serialize it first

  • Compute HMAC-SHA256(secret, "${timestamp}.${body}") where timestamp is the value from X-Smllr-Timestamp

  • Compare the hex digest to what follows sha256= in X-Smllr-Signature — if they don't match, reject the request

Step 3 — Send a Test Delivery

1

Find your endpoint

In Settings → Webhooks, locate the endpoint you just created.

2

Click Test

SMLLR immediately sends one sample payload to your URL and reports back pass/fail.

3

Check the delivery log

Click the history icon on the endpoint to see the HTTP status and response time of your test (and every future) delivery.

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