JSON Dev Tools is a free collection of browser-based utilities built for developers who work with JSON, APIs, and data formats every day. Every tool on the site runs entirely in your browser — your data is never sent to a server, never stored, and never shared.
I built JSON Dev Tools because I kept switching between four or five different sites every time I needed to format a JSON response, decode a JWT, or convert CSV data. Most of those sites are slow, cluttered with ads, or send your data to their servers. I wanted one fast, clean, private place to do all of these things.
The site launched in 2026. It started with a JSON formatter and has grown to include a validator, minifier, diff tool, converters, a JWT decoder, Base64 and URL utilities, and a timestamp converter — with more tools planned.
Every tool on JSON Dev Tools processes your data locally in JavaScript running in your browser tab. When you paste an API response, a JWT token, or a CSV file, that data is never transmitted to any server. The only data collected is standard analytics (page views and general usage patterns via Google Analytics), which helps understand which tools are most useful.
This site was built and is maintained by Pasindu Ishan, a software developer based in Sri Lanka. If you have questions, feedback, or a tool suggestion, feel free to reach out via the Contact page.
The focus is expanding the tool set — UUID generator, hash generator, JSONPath tester, JSON to TypeScript converter, and more utilities for working with structured data. The goal is to be the most useful, fastest, and most private developer toolkit available online.