webhooks.xyz

Examples / Messaging and communication / Slack

Slack webhooks

Events API: messages, reactions, channel and member changes, app mentions, slash commands and interactive payloads.

Events

  • message.channels
  • app_mention
  • reaction_added
  • member_joined_channel
  • url_verification

Signature

Headers X-Slack-Request-Timestamp and X-Slack-Signature. Signature is 'v0=' + HMAC-SHA256 of 'v0:<timestamp>:<raw body>' with the signing secret, hex encoded. Reject timestamps older than 5 minutes.

✓ A bin checks Slack signatures: add the signing secret under Signature verification (Slack).

Retries

Slack retries up to 3 times within an hour if it gets no 2xx in 3 seconds. Header X-Slack-Retry-Num counts the retries.

See a retry schedule in the calculator.

Docs

api.slack.com/apis/events-api

Checked 2026-10-08. Report a change.

Sample request from Slackillustrative, shortened
Content-Typeapplication/jsonX-Slack-Request-Timestamp1759924800X-Slack-Signaturev0=a2114d57b48eac39b9ad189dd8316235a7b4a8d21a10bd27519666489c69b503 
{
  "token": "verification-token",
  "team_id": "T0A9BC2DE",
  "api_app_id": "A0F7XDUAZ",
  "type": "event_callback",
  "event_id": "Ev0PV52K21",
  "event_time": 1759924800,
  "event": { "type": "app_mention", "user": "U061F7AUR", "text": "<@U0LAN0Z89> replay the failed orders", "channel": "C0LAN2Q65", "ts": "1759924800.000200" }
}

Receive Slack webhooks with webhooks.xyz

Create a bin. Paste its URL into Slack. Each request shows at once with its headers and body. Add your server as a destination, and deliveries retry when it is down. Request an invite.

More in messaging and communication: Discord, Telegram Bot API, Twilio, WhatsApp Business (Meta).