I built DevToolKit — a collection of 11 free browser-based tools and 30 API endpoints for developers. The entire business runs on Lightning payments (via Coinos).

Free tier: 50 API calls/day, all tools unlimited Paid: API keys and datasets, starting at 1,000 sats

The tools: password strength checker, website security scanner, privacy exposure check, JSON diff, regex tester, cron explainer, JWT debugger, sats calculator, free API directory, and a website status checker.

All payments go through Lightning Network. No fiat rails whatsoever. The checkout generates Coinos invoices and activates API keys upon payment confirmation.

Currently at 100 sats in the wallet — just getting started. The tools are the main draw; payments are there for anyone who wants higher API limits or the curated datasets.

Lightning address: devtoolkit@coinos.io