Take UPI payments. Keep every rupee.

Open-source, self-hosted payment confirmation for small Indian shops.
Customers pay with any UPI app, money lands straight in your bank, and Kaasu confirms the order.

Quick start · How it works · Design · Architecture · Roadmap · Contributing

Note

Pre-alpha, built in the open. Not ready for real money yet. Follow the roadmap.

Why Kaasu

• 0% fees. No gateway in the middle. Money goes from your customer's bank to yours.
• Hear every payment. "₹499 received" spoken on your phone, in your language.
• Hard to fool. Signed bank alerts, exact-amount + UTR matching, a tamper-evident ledger, and a review queue for anything doubtful.
• Yours. One Go binary and a SQLite file on your laptop, server or Railway. No account with us.

How it works

1. Your shop creates an order. Kaasu gives it a unique amount, like ₹499.07.
2. The customer pays with any UPI app, by link or QR.
3. Your bank sends its usual alert. The Kaasu Forwarder on your Android phone (or your email) passes it on, signed.
4. Kaasu matches it by amount, UTR and time, confirms the order, sends your shop a webhook and says it out loud. Anything that doesn't line up waits for your OK.

Features

Area	What you get
Checkout	Pay page · payment links · printable counter QR · JS snippet · WooCommerce plugin
Confirmation	Android Forwarder (SMS + app alerts) · bank email with DKIM · Mac Messages agent · cross-source dedupe
Merchant tools	Web dashboard (installable) · iPhone, Mac and Windows apps · review queue · reconciliation · refund log
Trust	Passkey sign-in · hash-chained ledger · signed webhooks · signed, reproducible releases
Languages	English, हिन्दी, தமிழ், తెలుగు, ಕನ್ನಡ, മലയാളം, मराठी, বাংলা, ગુજરાતી, ਪੰਜਾਬੀ, ଓଡ଼ିଆ
AI (optional)	Bring your own key or run a local model. Never confirms payments.

Quick start

Important

Lands with #2 and #51. The commands below are the target.

git clone https://github.com/opensawce/kaasu && cd kaasu
make dev

Runs everything offline with a demo shop and a payment simulator. Then fire a fake bank alert:

kaasu sim exact-match

Run it for your shop

Option	Best for
Mac or Windows app	Easiest. Keep the computer on.
One-line install on a Linux server	Recommended. Always on, HTTPS and backups set up for you.
Docker	Developers
Railway one-click	No server to manage

Limits

• Kaasu reads bank alerts; it is not connected to your bank. Alerts can be late or missing, so reconcile against your statement.
• Built for low-volume shops. Not a licensed payment gateway.
• Check your bank's terms for business use of your account.

Docs

• design.md: product, brand and UI spec
• architecture.md: system design, API, security
• AGENTS.md: rules for contributors and AI coding agents
• System design in Eraser: editable diagrams

Contributing

Code, bank alert formats, translations and docs are all welcome. Start with CONTRIBUTING.md: how to pick up an issue, the PR process, the one-click CLA, and the AI-assisted coding policy (AI is fine; you own every line).

Security

Please report vulnerabilities privately through GitHub Security Advisories, not public issues.

License

AGPL-3.0 © OpenSawce. A commercial license is available for uses the AGPL doesn't fit.