I will add crypto payment webhooks

A webhook that marks an order paid is the most attacked endpoint in your application. If anyone can forge it, anyone can get free goods. I build the receiving end properly.

I write the webhook handler in your stack and make it correct against the cases that actually break production:

- HMAC signature verified over the raw request body, in constant time

- Replay window enforced, so a captured request cannot be resent later

- Idempotency by event ID, so a duplicate delivery cannot fulfil an order twice

- Out-of-order and late events handled instead of trusted blindly

- Automated tests for every one of the above, so you can see it work

Works with Stripe, Coinbase Commerce, BTCPay, NOWPayments, or a custom sender. Python, FastAPI, Django, Flask, Node, Express. Tell me the sender and the stack.

Delivery is a pull request or a patch against your repository, with the tests, and a short written note on what I changed and why.

Everything is handled in writing through Fiverr messages. No calls or meetings needed - send me your sender's documentation and a description of your order model, and I will reply with the scope before you order.