Slack webhook tester
Debug Slack apps without re-installing them ten times.
Paste this URL into your Event Subscription / Interactivity endpoint. See every payload Slack sends, with the signing-secret headers intact.
See what Slack actually sends
The Block Kit JSON differs from what the playground shows. Inspect the real shape here.
Debug signing-secret mismatches
See `X-Slack-Signature` + `X-Slack-Request-Timestamp` together — most signature failures are timestamp drift.
Test slash commands without Slack admin
No need to re-install the app every time you change a route. Point the command at this URL during dev.
What Slack actually sends
POSTHeaders
Content-Type: application/json X-Slack-Signature: v0=a2114d57b48eac39b9ad189dd8316235a7b4a8d21a10bd27519666489c69b503 X-Slack-Request-Timestamp: 1716220800 User-Agent: Slackbot 1.0 (+https://api.slack.com/robots)
Body
{
"token": "XXYYZZ",
"team_id": "T12345678",
"api_app_id": "A0LAN2Q12",
"event": {
"type": "message",
"channel": "C0LAN2Q5G",
"user": "U2147483697",
"text": "Live long and prospect.",
"ts": "1716220800.000007"
},
"type": "event_callback",
"event_id": "Ev0LAN670R",
"event_time": 1716220800
}Get a URL Slack can hit in 30 seconds.
Free plan covers inspection + replay. Upgrade only when you need persistent mocks, forwarding, or longer history.
Other integrations
Other integrations under /apps.
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