Home / Developer Tools
Developer Tools JavaScript Projects
These are the small tools developers open every day, rebuilt as single HTML files you can keep, change and run offline. Format and check JSON, test regular expressions, send API requests and convert time zones. Each one is fast, private and shows useful techniques like Web Workers, streaming fetch and the new Temporal API.
047. JSON Formatter and Validator
Format, check and browse JSON, even large files
048. Regex Tester
Test regular expressions with live highlights and groups
049. Mini Postman API Client
Send API requests and read clean responses