Source type

Slack Source Configuration

Slack sources receive Events API callbacks and signed Slack requests, including the URL verification challenge Slack sends when a request URL is configured.

SLACKPOST, PUT, PATCH, DELETEWebhook Signing SecretCommunication
Slack Events API documentationAll source types
Slack sends webhook traffic to a FastHook source, FastHook validates the provider contract, records the request, and routes accepted events through connections to destinations.SlackProviderPOST, PUT, PATCH, DELETESetup + eventsFastHookSource URLSLACKProvider credentialchallengeVerify before queue401 on auth failure405 on wrong methodAcceptedRequestverified: trueConnections route the accepted request to destinationsFilters, transformations, retries, replay, and destination signatures stay downstream from source verification.Provider setupValidate firstSetup challenge

Slack configuration

Create a Slack source, keep POST and PUT and PATCH and DELETE enabled, and provide the configured Webhook Signing Secret values for provider signature. FastHook uses these settings to validate each Slack delivery before it enters the routing workflow.

Source Type

SLACK

Allowed methods

POST, PUT, PATCH, DELETE

Authentication

Provider signature

Credential fields

Webhook Signing Secret

Slack source config
{
  "type": "SLACK",
  "config": {
    "auth_type": "PROVIDER_SIGNATURE",
    "auth": {
      "provider": "SLACK",
      "webhook_signing_secret": "provider-secret"
    },
    "allowed_http_methods": ["POST","PUT","PATCH","DELETE"]
  }
}

URL verification before event callbacks

  1. Slack sends a signed url_verification payload to the Source URL.
  2. FastHook verifies the Slack signature and returns the challenge string as plaintext.
  3. After Slack accepts the challenge response, Events API callbacks continue as signed POST requests.

Slack request contract

FastHook verifies x-slack-signature by signing v0:timestamp:raw-body and checks the timestamp tolerance.

POSTPUTPATCHDELETE

Special response: For Slack url_verification payloads, FastHook returns the challenge string as text.

Slack headers

Preserve x-slack-signature, x-slack-request-timestamp when sending Slack test deliveries. FastHook evaluates this request context before accepting the payload, so missing or modified values remain visible as rejected requests instead of routed events.

x-slack-signature

v0 HMAC-SHA256 request signature.

x-slack-request-timestamp

Unix timestamp included in the signed payload.

Slack setup

  1. Create a Slack app and enable the Events API.
  2. Paste the FastHook Source URL into Slack's Request URL field.
  3. Use Slack's signing secret in the FastHook Webhook Signing Secret field.

Slack routing hints

  • Events API callbacks usually route by Slack event.type and team_id after URL verification succeeds.
  • Keep inbound Slack event handling separate from outbound Slack notification destinations.

Continue with Slack