Launched this week

Invariant

Launched this week

Open-source business invariant engine for payment webhooks

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Open-source business invariant engine for payment webhooks

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Invariant is an open-source CLI engine that continuously tests Stripe & Razorpay webhooks against real-world edge cases (duplicate deliveries, out-of-order refunds, tampered HMAC signatures) and mathematically proves database state post-conditions in under 10 seconds. - 🔒 100% Offline & Private (localhost) - ⚡ Zero Telemetry & Instant Local Execution - 🛡️ Works with Node.js, Python, Go, Java, Ruby Try it: npx @yavona/invariant init

Free

Launch tags:Open Source•Fintech•Developer Tools

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Hey Product Hunt! 👋 Every backend engineer who has integrated Stripe or Razorpay knows this feeling: your webhook handler returns HTTP 200 OK, but a duplicate event retry or out-of-order refund silently double-credits a user's ledger in your database. Standard tools like `stripe trigger` only test if an HTTP request was sent—they don't verify if your DB mutations satisfied business post-conditions. We built **Invariant** (`@yavona/invariant`) to solve this. Invariant dispatches provider-accurate payloads and queries a 5-line dev state probe (`/api/db-state`) to assert DB state post-conditions in under 10 seconds. It's 100% MIT open-source, private, and works offline against localhost. We'd love your feedback, ideas, and support! 🚀

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1d ago