Developer outbound webhooks

Events

• post.published — a post successfully published
• post.failed — publish failed (scheduled or immediate)

Payloads are JSON envelopes with type, createdAt, and data (post and workspace ids).

Register an endpoint

1. Use an HTTPS URL you control (n8n Webhook, Make Custom webhook, Zapier Catch Hook, etc.).
2. In CatCaster, open Settings → Developer → Outbound Webhooks and add the URL, or call POST /api/v1/webhooks with your API key (API overview).
3. Store the signing secret shown once at creation.

Verify signatures

CatCaster sends header CatCaster-Signature: t=<unix>,v1=<hex>. Compute HMAC-SHA256 over {t}.{rawBody} with your signing secret and compare to v1. Reject stale timestamps in production.

Automation guides

• n8n — Webhook trigger + community node for actions
• Make — Custom webhook + OpenAPI modules
• Zapier — Catch Hook + REST actions (packages/zapier-catcaster)

Inbound vs outbound

Outbound (this page): CatCaster → your URL when your workspace publishes content.

Inbound (platform): Meta, X, Apple, and similar send events to CatCaster for channel connectivity — that is internal publishing infrastructure, not the public developer webhook product.