How do I handle Slack's url_verification challenge?

Slack sends a one-time url_verification event when you add your webhook URL. HookSense lets you inspect and respond to the challenge; you can configure a custom response so Slack accepts the endpoint instantly.

Can I test Slack slash commands without deploying my app?

Yes. Point the slash command's Request URL at HookSense, trigger it from any Slack channel, then replay the captured request to your localhost handler — with the 3-second timeout handled via custom responses during testing.

Does HookSense verify the X-Slack-Signature header?

Yes. Slack uses HMAC-SHA256 with your Signing Secret. Add the secret to HookSense and signatures are validated automatically on every incoming request.

Slack Webhook Tester

Test Slack webhooks in real-time — no signup, no tunnels.

Get a free webhook URL in one click, paste it into your Slack dashboard, and watch events stream in live. Verify X-Slack-Signature signatures automatically, replay any request to your local server, and debug payloads with search and filters.

Get a free Slack webhook URL Full Slack setup guide

Why test Slack webhooks with HookSense

Real-time WebSocket stream

Events appear the instant Slack sends them. No polling, no refresh button.

HMAC-SHA256 verification

Paste your signing secret once — HookSense verifies every Slack request automatically.

One-click replay

Send any captured webhook back to your local server or production — rerun your handler without triggering new events.

CLI forwarding, no ngrok

Forward directly to localhost:3000 with npx hooksense listen.

Quick start — 3 steps

1
Get your free webhook URL
Create a free endpoint at hooksense.com. You get a unique URL instantly — no credit card, no config.
2
Paste it into Slack
In the Slack dashboard, add the URL as your webhook endpoint and pick the events you want (message, app_mention, etc.).
3
Trigger an event and watch it arrive
Fire a test event from Slack — it lands in HookSense within milliseconds. Inspect headers, body, and signature. Replay when ready.

Forward to localhost

npx hooksense listen -p 3000 --path /api/integrations/slack

Common Slack webhook events

message

app_mention

channel_created

member_joined_channel

reaction_added

slash command

interactive message

view submission

Testing tips specific to Slack

Slack requires a 200 response within 3 seconds — use HookSense custom responses to test timeout handling
The Events API sends a url_verification challenge on first setup
Use HookSense to debug interactive component payloads (buttons, modals, menus)
Slack's signing secret is different from your Bot Token — use the Signing Secret from App Credentials

Frequently asked

How do I handle Slack's url_verification challenge?: Slack sends a one-time url_verification event when you add your webhook URL. HookSense lets you inspect and respond to the challenge; you can configure a custom response so Slack accepts the endpoint instantly.
Can I test Slack slash commands without deploying my app?: Yes. Point the slash command's Request URL at HookSense, trigger it from any Slack channel, then replay the captured request to your localhost handler — with the 3-second timeout handled via custom responses during testing.
Does HookSense verify the X-Slack-Signature header?: Yes. Slack uses HMAC-SHA256 with your Signing Secret. Add the secret to HookSense and signatures are validated automatically on every incoming request.

Test webhooks from other providers

Start testing Slack webhooks now

Free plan includes 100 requests/day, 7-day retention, real-time streaming. No credit card.

Create a free endpoint