A free PlantUML editor that runs entirely in your browser. The official engine is compiled to JavaScript, so your diagram source is never uploaded. Live preview, PNG/SVG export, templates, share links and offline support. No account, no Java, no Graphviz.
Explore at https://localonly.dev/plantuml/

The privacy-first angle is really appealing, especially for working with sensitive data. One thing that would make this even more useful for me would be a built-in diff tool for comparing two JSON payloads side by side, something that highlights added, removed, and changed keys. It would save me from constantly toggling between tabs.
@kaanhsdo thanks for your feedback, and really happy to know my https://localonly.dev/ is helping you..!
Tried the JSON formatter and it handled a messy nested file without lagging, which is more than I can say for most tools. Love that nothing leaves the browser, this is exactly what I want for quick dev tasks.
Hi @aysun1793938, Thank you so much! ❤️
Really glad you found it useful. Keeping everything fast, simple, and 100% in the browser is exactly what we’re aiming for.
Please explore more at: https://localonly.dev/