I built a cryptocurrency screener—it’s got over 400 coins and I’m aiming for 10,000! 
It’s super fast because all the filtering happens on the server, not your browser. You can set up custom filters using AND/OR, and it calculates things like RSI. 
It’s built with F# and TypeScript, and it’s part of a bigger backtesting platform I’m working on solo. I'd love to hear what you think, especially about the user experience. Check it out here: [https://cryptoquant.dev/instruments/screener].