Your files stay on your device

Validate JSON

Paste a document, get the exact lines where it breaks, then walk the tree. Strict JSON or JSONC, nothing uploaded.
Strict JSONJSONCInsert sampleInsert broken sampleClear

Strict mode: no comments, no trailing commas (RFC 8259)

Paste JSON to see diagnostics, the tree, and line-level stats.
Paste, drop, or type to begin. Everything stays on this device.

More JSON tools

- JSON formatter (/json/formatter)
- JSON query (/json/query)
- JWT decoder (/web/jwt)
All JSON tools (/json)

Canonical HTML: https://nutter.tools/json/validator/
Markdown version: https://nutter.tools/json/validator/index.md
Plain-text version: https://nutter.tools/json/validator/index.txt
Agent index: https://nutter.tools/llms.txt