RESTCaptcha

RESTCaptcha is a lightweight, privacy-friendly CAPTCHA solution that requires no image puzzles, no third-party tracking, and no persistent server-side sessions.

Instead, it uses proof-of-work to verify human interaction with your form.

Features:

• Stateless challenge using HMAC-signed nonce
• Client-side proof-of-work puzzle (SHA-256 or SHA-512 hash under threshold)
• CDN-ready restcaptcha.js script with pluggable API endpoint
• Fully customisable
• Fully integrable with Node.js, PHP, ASP.NET or any other server technology
• Support for different modes (interactive, auto, invisible, headless)
• Support for multiple languages
• Build with .NET 9 and JavaScript.

Technology stack

• ASP.NET 9 as web framework
• JavaScript for the restcaptcha.js client script

Getting started

Documentation is available in the GitHub wiki.

Can I help?

Yes, that would be much appreciated. The best way to help is to post a response via the Issue Tracker and/or submit a Pull Request.