Anvil

Webhooks that run once, even when the provider sends them twice.

  • TypeScript
  • Node.js
  • Express
  • Redis
  • BullMQ
  • Docker
Codenpm

The problem

Stripe and GitHub re-deliver webhooks, and a worker that crashes after doing the work gets the same event again, so you charge a card twice.

How it works

Anvil is an Express server in TypeScript with a BullMQ worker behind it.

  1. Verify. It checks the signature over the raw request body, before anything parses it, with a constant-time compare.
  2. Dedupe. It keys each delivery on a hash of the signature plus the payload and remembers it in Redis, so a repeat is dropped.
  3. Enqueue. Each valid delivery becomes one BullMQ job, so the sender gets a reply right away and a worker does the real work in the background.
  4. Retry, then stop. A failing job retries on a fixed schedule, then moves to a dead-letter queue instead of retrying forever.
  5. Replay by hand. The dead-letter queue is never drained by the worker. Replaying a job is a separate, deliberate step, so a job that always fails cannot loop.

It is packaged with Docker and published on npm.

What it does not do

  • You map each provider's signature header yourself.
  • Replay moves one job at a time.
  • BullMQ on Redis is the only queue backend.

Links