Slack, Teams and Discord

Slack, Microsoft Teams and Discord each give a channel a webhook URL that posts whatever it receives — but only in their own message format, so they reject the event envelope we normally send. A transformation bridges the gap. By the end of this guide you'll have:

• an endpoint aimed at your channel's webhook URL;
• the preset for that app turning each event into a message it accepts;
• a test event posted in the channel.

Total time: about 10 minutes.

Prereqs

• A Webhooks workspace on Starter, Pro or Custom. Free does not include transformations.
• The right to add a webhook to the channel: in Slack, to install an app in the workspace; in Teams, to create a workflow; in Discord, the Manage Webhooks permission.
• Endpoint verification off for the project the endpoint goes in. These channels take only their own messages, so they can never answer the verification challenge, and an endpoint that must pass it receives nothing. Paid plans can turn verification off.

1 · Get the channel's webhook URL

Slack

Create a Slack app for your workspace and turn on Incoming Webhooks in its settings. Choose Add New Webhook to Workspace, pick the channel and authorize it. Copy the URL, which looks like https://hooks.slack.com/services/T…/B…/…. Slack's own steps are in Sending messages using incoming webhooks.

Microsoft Teams

In Teams, open Workflows and start from the template Send webhook alerts to a channel. Choose the team and the channel, save the workflow, and copy the webhook URL from its details. Microsoft's own steps are in Create incoming webhooks with Workflows for Microsoft Teams.

Discord

In Discord, open Server Settings → Integrations → Webhooks and create a webhook. Pick the channel it posts to, then Copy Webhook URL, which looks like https://discord.com/api/webhooks/…/…. Discord's own steps are in Intro to Webhooks.

Treat the URL as a secret: these channels don't check our signature, so anyone who has it can post to the channel.

2 · Add the endpoint

In the console, choose New endpoint on the Endpoints page, paste the URL, and subscribe it to the events the channel should see. Keep the list short: a channel is read by people, and every matching event becomes a message.

Through the API:

curl -sX POST https://webhooks.nimbusnexus.net/v1/endpoints \
  -H "Authorization: Bearer $ADMIN_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url": "https://hooks.slack.com/services/T…/B…/…", "project_id": "prj_…",
       "subscriptions": [{"match_kind": "exact", "pattern": "invoice.paid"}]}'

3 · Choose the preset

Open the endpoint's menu on the Endpoints page and choose Transformation. Select Preset, then the one for your app — Slack message, Microsoft Teams card or Discord message — and Save. From now on, each delivery to this endpoint is sent as a message:

Each one cuts the data to fit the app's own limit, such as 3,000 characters in a Slack section or 2,000 in a Discord message.

A preset is a script like any other, so there is nothing to name through the API: create a transformation with the script you want. The console's Edit this script shows each preset's code to start from.

4 · Test it

Under Test on the same page, choose Run test. It runs the preset against a recent event from the endpoint's deliveries, or one you paste, and shows the message it would send. Nothing is sent.

Then send a real one: Send test event on the console's Overview, or publish an event the endpoint subscribes to:

curl -sX POST https://webhooks.nimbusnexus.net/v1/events \
  -H "Authorization: Bearer $ADMIN_KEY" \
  -H "Content-Type: application/json" \
  -d '{"event_type": "invoice.paid", "project_id": "prj_…", "payload": {"id": "in_123", "amount": 125000, "currency": "usd"}}'

The message appears in the channel within a few seconds. The endpoint's Send test ping is no use here: it sends its fixed ping untransformed, and the channel turns it away.

What you've done

Every event the endpoint subscribes to now posts a message in your channel. Open a delivery on the Deliveries page to see the message that was sent; if the app answered with an error, it is there too, under the delivery's attempts.

Making it your own

Choose Edit this script to change what the message says or which events post one. Returning null sends nothing, so a script can keep the channel for the events people need. For Slack:

function transform(event) {
  if (event.type !== "invoice.paid" || event.data.amount < 100000) return null;
  return { body: { text: `Invoice ${event.data.id} paid: ${event.data.amount / 100} ${event.data.currency}` } };
}

For Discord, send content where Slack takes text; for Teams, keep the preset's card and change the text in it. A delivery the script drops is not sent and does not count as failed. Test the script before you save it: a run that fails sends the delivery to the dead-letter queue, never the untransformed event.

Next steps

• Transformations — the script contract, limits and what happens when a script fails.
• Endpoint verification — receivers that cannot answer the challenge.
• Deliveries and retries — states, retries and sending again.