Test Zendesk Webhooks Locally (Receive Zendesk Webhooks on localhost)

You are building a Zendesk integration and you need to watch your handler react to a real event. The problem hits immediately: Zendesk will only POST to a public URL, and your handler is running on localhost:8080. Zendesk has no way to reach it.

The usual workarounds are slow. Deploying to a staging environment for every code change kills your iteration speed. Copying a sample payload out of the docs into curl gives you a guess at the real request, not the exact headers and body Zendesk actually sends. What you really want is to test Zendesk webhooks locally — real events, hitting your local handler, on a URL that does not change every time you restart.

This guide shows how to do exactly that.

Why testing Zendesk webhooks locally is tricky

A webhook is just an HTTP request that Zendesk sends to a URL when something changes. Zendesk lives on the public internet; your dev machine usually does not. It sits behind a router, a corporate firewall, or both, with no public IP and no inbound ports open.

So you need something in the middle: a public endpoint Zendesk can hit that relays each request down to your laptop without you opening a single firewall port. That is what Webhook Relay does — and unlike a random tunnel URL, the endpoint is stable, so you configure Zendesk once and never touch it again.

Step 1: Inspect the real payload with Webhook Bin

Before you write any handler code, find out what Zendesk actually sends. Open the free Webhook Bin — no signup — and you get an instant public URL.

1. Copy the Webhook Bin URL.
2. In Zendesk Admin Center, go to Apps and integrations → Webhooks → Create webhook, set the URL, turn on signing, then connect it to a trigger or automation.
3. Trigger a real event and inspect the captured request.

You will see the full body and every header. A Zendesk webhook sends whatever JSON you define in the connected trigger. With signing on, each request includes X-Zendesk-Webhook-Signature and X-Zendesk-Webhook-Signature-Timestamp headers.

Now you know the exact shape of the data before writing a line of code. For more on this approach, see How to test webhooks and What is a webhook.

Step 2: Forward the events to localhost with the relay agent

Once you know the payload, route those same events into your local handler. Sign up for Webhook Relay, install the relay agent (CLI or Docker), and create a bucket — say zendesk. The bucket gives you a stable public input endpoint.

Start forwarding to your local server:

relay forward --bucket zendesk http://localhost:8080/webhook

The agent opens an outbound connection to Webhook Relay and streams every incoming request down to http://localhost:8080/webhook. Because the connection is outbound, there are no firewall ports to open and no public IP needed — this works from your laptop, behind a corporate proxy, or inside a Kubernetes cluster. Running in Docker? The same command works in the official webhookrelay/webhookrelayd image. Full details are in the localhost forwarding docs.

Now point the Zendesk webhook at your Webhook Relay endpoint (or create it there from the start), trigger an event, and watch it arrive on localhost.

Zendesk-specific configuration and quirks

A few Zendesk details worth knowing:

• Where to add it: Admin Center → Apps and integrations → Webhooks; connect it to a trigger or automation to fire it.
• Custom body: you template the JSON in the trigger, so the payload shape is whatever you define.
• Signing: enable it to get the signature headers.

Step 3: Verify the Zendesk webhook signature

Zendesk signs "{timestamp}{raw body}" with HMAC-SHA256 using the webhook's signing secret, base64-encodes it, and sends it in the X-Zendesk-Webhook-Signature header alongside X-Zendesk-Webhook-Signature-Timestamp. Rebuild timestamp + rawBody, compute the HMAC, base64-encode, and compare in constant time.

To sanity-check an HMAC implementation, paste a captured body, your secret, and the received signature into the free HMAC signature verifier. For language-specific code and the common pitfalls (reading the body after a JSON parser has already consumed it, timing-safe comparison), read Verify a webhook signature.

Replay and iterate

This is where local development gets fast:

• Replay from Webhook Relay — past requests are stored on your bucket, so you can resend a captured event against your handler without touching Zendesk at all.
• Iterate on your handler by editing code and replaying the same delivery until it behaves correctly. No commits, no pushes, no deploys just to test a single code path.
• Keep relay forward running while you work — events stream straight to localhost as you trigger them in Zendesk.

Because the Webhook Relay endpoint is stable, you can stop and restart the agent, reboot your machine, or come back next week — the Zendesk configuration never needs to change.

Get started

1. Inspect the real payload in the free Webhook Bin — no signup needed.
2. Create a Webhook Relay account, install the agent, and run relay forward --bucket zendesk http://localhost:8080/webhook.
3. Point your Zendesk webhook at the stable endpoint, trigger an event, and watch it hit localhost.

You will be testing real Zendesk events against your local handler in a few minutes — no deploys, no open firewall ports, and a URL you configure exactly once.