Stop Switching Tabs — One Free Tool Replaces All Your JSON & Dev Tools

Source: Dev.to

Introducing JsonMaster

JsonMaster is a free, all‑in‑one developer toolbox that consolidates 12 useful utilities into a single tab.

• No login required
• No ads
• Your data never leaves the browser (100 % client‑side)

Core Features

JSON Formatting & Conversion

• Beautify raw or minified JSON with Monaco Editor (the same engine as VS Code) – includes syntax highlighting, inline error squiggles, code folding, and familiar keyboard shortcuts.
• Convert JSON to:
  • YAML – ideal for Kubernetes, Docker Compose, GitHub Actions
  • CSV – ready for Excel, Google Sheets, data pipelines
  • XML – for legacy systems and SOAP APIs
  • TypeScript Interface – generate a typed interface instantly from an API response
  • Zod Schema – create runtime validation schemas for TypeScript projects
  • .env file – flatten nested JSON into environment variables

JWT Decoder

• Paste any JWT and instantly view the header, payload, and signature.
• Checks token expiry and algorithm.
• All processing happens locally in the browser.

Base64 & URL Encoder/Decoder

• Encode or decode Base64 and URL strings instantly.
• Handles Unicode correctly – perfect for auth headers, query strings, and embedded images.

Regex Tester

• Write a pattern and test it against your input in real time.
• All matches are highlighted; supports all JavaScript regex flags (g, i, m, s, u).
• Displays match groups and count.

JSON Diff

• Paste two JSON objects and see exactly what was added, removed, or changed, down to the specific key path.
• Great for comparing API responses before and after a deployment.

Privacy & Security

Most JSON tools send your data to a server, exposing sensitive information.
JsonMaster runs entirely in the browser—open DevTools → Network tab while using it and you’ll see zero outgoing requests for your data. This is crucial when handling:

• JWT tokens
• API responses containing user data
• Configuration files with credentials

Try It Free

Give JsonMaster a spin. If you encounter a bug or have a suggestion for a new tool, feel free to drop a comment—feedback is always welcome.