WebhookProof Payment Webhook Linter

Finds the most common fatal bugs in payment webhook handlers before launch

Problem

Payment bugs rarely live in Stripe or Paddle—they live in webhook handler code: signature verification using parsed JSON instead of raw body, no duplicate event handling, missing event IDs. These surface only after launch, causing billing errors and missed payments.

Solution

A dev-stage testing tool that sends simulated events (replays, out-of-order, duplicates, malformed signatures) to your configured webhook endpoint and checks whether your handler is idempotent and verifies signatures correctly. Outputs a readable health report.

Users

SaaS developers using Stripe/Paddle, indie hackers, small-team backend engineers

MVP

Simulate Stripe/Paddle test-mode events; detect whether signature verification uses raw body; test idempotency against duplicates; generate a report with fix suggestions; CI integration

Revenue

Subscription per project (fixed monthly test runs) or one-time purchase for CI plugin; paid deep scans

Why now

Subscription SaaS is booming and payment webhooks are nearly universal, yet test tooling is scarce—an indie dev can ship a vertical tool fast