Slack Integration

Set up HookWatch to receive Slack webhooks for workspace events like messages, reactions, channel updates, and app interactions.

Prerequisites

A HookWatch account
A Slack app with Event Subscriptions enabled
A server endpoint to process webhook payloads

Step 1: Create a HookWatch endpoint

Go to your Endpoints page
Click "Create Endpoint"
Enter a name like "Slack Webhooks"
Enter your destination URL (where you want webhooks forwarded)
Copy the generated webhook URL

Your HookWatch URL will look like:

https://hook.hookwatch.dev/wh/abc123xyz

Step 2: Configure Slack Event Subscriptions

Go to Slack API > Your Apps
Select your app (or create a new one)
Click "Event Subscriptions" in the sidebar
Toggle "Enable Events" to On
Paste your HookWatch URL in the "Request URL" field
Under "Subscribe to bot events", add the events you want
Click "Save Changes"

Common events to subscribe to:

message.channels

message.groups

message.im

reaction_added

app_mention

member_joined_channel

channel_created

file_shared

Step 3: Verify webhooks on your server

Slack signs webhook payloads using HMAC-SHA256. HookWatch forwards the X-Slack-Signature and X-Slack-Request-Timestamp headers so you can verify authenticity.

You'll find your signing secret in your app's Basic Information > App Credentials section.

Node.js / Express

Slack webhook headers

HookWatch forwards all Slack headers. Here are the important ones:

Header	Description
`X-Slack-Signature`	HMAC-SHA256 signature for verification
`X-Slack-Request-Timestamp`	Unix timestamp of the request
`Content-Type`	Always application/json for Event Subscriptions

URL Verification

When you first set the Request URL, Slack sends a url_verification challenge. Your server must respond with the challenge value. Make sure your forwarding destination handles this before configuring the URL in Slack.

Testing the integration

Send a message in a channel your bot is in
Mention your app with @YourApp
Add a reaction to a message
Check your HookWatch Events page to see the events

Common issues

URL verification fails

Make sure your destination server responds to the url_verification challenge within 3 seconds. Slack requires an immediate response with the challenge token.

Not receiving events

Check that your bot has been invited to the channels you want to monitor. Bot events only fire for channels where the bot is a member.

Duplicate events

Slack may retry events if it doesn't receive a 200 response within 3 seconds. Use the event_id field to deduplicate on your server.