Cap: Lightweight, modern open-source CAPTCHA alternative using proof-of-work

Summary

What is Cap? Cap is a lightweight, modern open-source CAPTCHA alternative using SHA-256 proof-of-work. It's fast, private, and extremely simple to integrate. Learn more about proof-of-work here.Cap is built into 2 main parts:@cap.js/widget: A small JavaScript library that renders the CAPTCHA and handles solving it using Web Workers and WASM.@cap.js/server: An extremely simple, zero-dependencies library that handles creating and validating challenges.There are also some other helpful packages:@cap.js/solver: Server-side solver for the CAPTCHA in case you want to use machine-to-machine.@cap.js/cli: Command-line interface for solving CAPTCHAs made with Cap. It's mainly designed for testing and when you need to solve these CAPTCHAs in a browser without JavaScript support.Standalone mode: Docker image that helps you use Cap with any language or framework. It runs a simple REST API that can be used to create and validate challenges and an interactive UI to manage your keys.@cap.js/wasm: WASM solvers for Node and Web built with Rust.We also provide a middleware for a Cloudflare browser checkpoint-like experience:It's designed to be a drop-in replacement for existing CAPTCHA solutions, with a focus on performance and UX.Cap is built with JavaScript, runs on any JS runtime (Bun, Node.js, Deno), and has no dependencies. If you're not using any JS runtime, you can also use the standalone mode with Docker, which relies entirely on a simple REST API to create and validate challenges.Why Cap? 250x smaller than hCaptcha@cap.js/widget is extremely small, only 12kb minified and brotli'd.Private Cap's usage of proof-of-work eliminates the need for any tracking, fingerprinting or data collection.Fully customizable Cap's self-hostable so you can customize both the backend & frontend — or you can just use CSS variablesProof-of-work Cap uses proof-of-work instead of complex puzzles, making it easier for humans and harder for botsStandalone mode Cap offers a standalone mode with Docker, a...