About JSONLint
JSONLint has been the go-to JSON validator since 2010. It does one thing — validate and format JSON. But the web has moved on. It shows ads, has no dark mode, sends your data to a server, and lacks features that modern developers expect (diff, conversion, offline support).
Strengths
- The original — widely known and referenced
- Simple and focused
- Fast validation
Why look for alternatives?
- Displays advertising
- No dark mode or modern UI
- Data sent to server for processing
- No JSON diff, conversion, or other tools
- No offline support
Best JSONLint Alternatives
1. JSON Knife — Best overall alternative
19 developer tools in one site. Format, validate, diff, and convert JSON — plus Base64, URL encode, JWT decode, regex tester, SQL formatter, and more. Everything runs client-side (your data stays in your browser), no ads, dark theme, works offline.
Best for: Developers who want one bookmarkable tool for everything
2. JSON Editor Online — Best visual editor
Side-by-side code and tree view panels. Edit JSON visually with drag-and-drop. Supports JSON Schema validation. More of an editor than a formatter.
Best for: Developers who need to visually explore and edit large JSON documents
3. JSON Hero — Best for API exploration
Beautiful column-based JSON viewer that auto-detects dates, URLs, colors, and images inside JSON values. Open source. Read-only — no editing or formatting.
Best for: Exploring complex API responses with deeply nested data
4. Code Beautify — Most tools in one place
100+ formatters and converters for every language and data format. JSON tree view, diff, and conversion included. Trade-off: heavy ads and cluttered interface.
Best for: Developers who work with many file formats beyond JSON
5. JSON Formatter (curiousconcept.com) — Strictest validation
Validates JSON against specific RFC standards (RFC 8259, RFC 7159). Shows detailed error messages. Good for strict compliance checking.
Best for: Ensuring JSON complies with a specific RFC standard