Signed payloads. Every webhook is signed with HMAC, so the receiving service can verify the message really came from your DChat server and was not tampered with.
A durable outbox. Outgoing webhooks are queued and retried on a backoff schedule, so a brief outage at the other end does not lose a notification. Failed deliveries are visible and can be retried from the admin view.
Your own systems too. Beyond the three chat tools, webhooks can point at any endpoint you own, and the API and direct SQL access let you feed chat data into a CRM or data warehouse.