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Invariant
Open-source business invariant engine for payment webhooks
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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About Invariant on Product Hunt
“Open-source business invariant engine for payment webhooks”
Invariant was submitted on Product Hunt and earned 0 upvotes and 1 comments, placing #83 on the daily leaderboard. 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
Invariant was featured in Open Source (68.8k followers), Fintech (47.5k followers), Developer Tools (518.8k followers) and GitHub (41.4k followers) on Product Hunt. Together, these topics include over 145.3k products, making this a competitive space to launch in.
Who hunted Invariant?
Invariant was hunted by YavonaLabs. A “hunter” on Product Hunt is the community member who submits a product to the platform — uploading the images, the link, and tagging the makers behind it. Hunters typically write the first comment explaining why a product is worth attention, and their followers are notified the moment they post. Around 79% of featured launches on Product Hunt are self-hunted by their makers, but a well-known hunter still acts as a signal of quality to the rest of the community. See the full all-time top hunters leaderboard to discover who is shaping the Product Hunt ecosystem.
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