What is sentinelle?

Sentinelle is a self hosted crypto invoicing gateway that a shop can plug into to accept payment in Bitcoin, Ethereum, Solana, or their supported stablecoins, while showing prices in Bitcoin, euros, or dollars. When an order is created, it generates an invoice that stays valid for a set window of time, fifteen minutes by default, and can be paid across whichever payment rails the shop operator turns on. Its main safety feature is that it never holds spending power. Every rail is watch only, meaning only public keys or addresses are stored on the server. Bitcoin and Ethereum addresses are derived from a public account key called an xpub, so a fresh receiving address can be generated for each invoice without the server ever having access to a private key that could move funds. Solana payments instead use a unique per invoice reference tied to a single wallet address. Lightning payments are handled through the operator's own phoenixd node and confirmed in real time over a WebSocket connection. The system also guards against a few subtle bugs common in payment software. It tracks Bitcoin and Ethereum address indexes carefully so they cannot overflow, and it recycles the addresses of invoices that expire unpaid instead of burning them forever. All monetary amounts are stored as whole numbers of satoshis or cents rather than floating point numbers, avoiding rounding errors. Sentinelle ships with a React and Tailwind based admin dashboard for managing settings, API keys, and a sortable list of invoices, plus real time payment notifications over WebSocket and email, manual reimbursements, and an accounting export in CSV or XLSX format with the exchange rate locked at the moment of each order. It runs as a Node.js server backed by a SQLite database, is available as a prebuilt Docker image, and exposes a simple HTTP API for creating invoices that shops can integrate with directly.