How to create a Slack webhook URL

1. 1
   Create a Slack app

   Go to api.slack.com/apps and click Create New App → From scratch. Name it (e.g. “Form Notifications”) and pick the Slack workspace it lives in. The app is just a container; nothing posts yet.
2. 2
   Enable Incoming Webhooks

   In the app's left sidebar, click Incoming Webhooks. Toggle Activate Incoming Webhooks to On. That unlocks the “Add New Webhook to Workspace” button at the bottom of the page.
3. 3
   Add a webhook to a workspace and pick the channel

   Click Add New Webhook to Workspace. Slack asks you to authorise the app and pick a channel — private channels work too, but you need to be a member. This is the channel every POST to this URL will land in. Click Allow.
4. 4
   Copy the webhook URL

   Slack drops you back on the Incoming Webhooks page with a new row in the Webhook URLs table. Click Copy. The URL looks like https://hooks.slack.com/services/T.../B.../<long-random>. Treat it like a password — anyone with it can post to that channel.
5. 5
   Test it

   Paste the URL into the Slack Webhook Tester and click Send test to Slack. If you see the test message in your channel within a second, the URL works. If you see HTTP 404 / no_service, you copied a stale URL — regenerate from step 4.
6. 6
   Wire it into a Google Form

   Two options. Free DIY: paste the URL into the Google Forms to Slack Generator and copy the emitted Apps Script into your form. Managed: paste it into RouteForms and add routing rules so different answers go to different channels, with a delivery log and retries on failure.

• HTTP 404 / no_service / no_team — the URL was revoked, deleted, or never existed at that path. Regenerate the webhook (step 4 above) and grab the new URL.
• HTTP 403 / invalid_token — Slack rejected the request as unauthorised. Re-create the webhook from the Incoming Webhooks page; the old one is dead.
• HTTP 400 / invalid_payload — the URL is good but your request body is wrong. Almost always a missing Content-Type: application/json header or malformed JSON.
• HTTP 400 / invalid_blocks— Slack accepted the request but couldn't render the blocks. Use the Block Kit payload generator to build a known-good shape.
• HTTP 429— you're sending too fast. Back off and retry.
• Timeout— the request couldn't reach Slack. If only one machine times out, check that machine's outbound network. If everyone times out, Slack status page.

The Slack Webhook Tester translates each of these into plain English so you don't have to memorise Slack's error vocabulary.

A Slack webhook URL is a destination, not a channel and not a user. The URL embeds:

• The workspace — the part starting with T....
• The app — the part starting with B....
• A secret — the trailing path segment that authorises the POST.
• The channel — bound at creation time, not visible in the URL itself.

Revoke a URL by deleting its row on the Incoming Webhooks page. A new POST to the revoked URL returns no_service.