DevUtilX gathers a large set of small developer tools in one place. You can beautify JavaScript and TypeScript, minify code, encode and decode strings, validate data, and run all sorts of conversions, all inside the browser.
Beyond code, there are unit converters, image and media helpers, API and data tools, text utilities, and cheatsheets. Everything is free and needs no installation, which makes it handy to bookmark for quick tasks during the working day.