JSON toolbox:formatter & validator.
Format, validate, diff, query, and convert JSON in a UI that doesn't feel like 2008. No signup, no upload, and every core tool runs in your browser.
- 100% client-side
- No tracking
- No signup
- Built for the terminal generation
JSON Formatter
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What developers should find first.
Format, validate, diff, query, and convert JSON in your browser. Free, client-side JSON tools with no signup and no upload.
- JSON FormatterPretty-print and validate JSON with line-accurate errors. Sort keys alphabetically. Client-side with no signup or upload.
- JSON Schema ValidatorValidate JSON against JSON Schema drafts 07, 2019-09, and 2020-12 with per-path errors. No upload, no signup.
- JSON DiffCompare two JSON documents by structure and see added, removed, and modified values by JSON Pointer path.
- JSON Tree ViewerBrowse JSON as a collapsible tree, expand nested data, and inspect structure in your browser with no upload.
- JWT DecoderDecode JWT header, payload, expiry, and claims in your browser. Client-side JWT inspection with no upload.
- JSON to TypeScriptGenerate TypeScript types from sample JSON in your browser. Fast, private, and powered by JSONZen.
Every tool, one tab.
One stop for everything we wish JSON tools were. Local-first, keyboard-first, fast.
Start with a JSON formatter and validator, then move through semantic diff, tree view, JSONPath, JWT decoding, and code generation without uploading data or creating an account.
Format
Pretty-print JSON with line-accurate errors. Sort keys on demand.
Validate
Check a JSON document against a JSON Schema. Per-path error messages.
Minify
Strip whitespace and shrink your JSON payload. Reports bytes saved.
Tree View
Browse JSON as a collapsible tree. Drill into nested data without scrolling.
Semantic Diff
Compare two JSON files by structure. Per-path adds, removes, modifications.
JSONPath / JMESPath
Run live JSONPath and JMESPath queries against your JSON.
JSON Deep Equality
Yes/no equivalence check between two JSON documents, with the first difference shown as a JSON Pointer.
JSON Flatten / Unflatten
Convert nested JSON to a flat dot-path map and back. Bracket or index array notation.
JSON Schema → Mock Data
Generate realistic sample JSON from a schema. Deterministic with a seed; respects enum, format, ranges.
JSON ↔ TypeScript
Generate type definitions from sample JSON. Powered by quicktype. Reverse it too.
JSON → Zod
Generate Zod runtime validators from JSON. TypeScript-first.
JSON → Pydantic
Generate Pydantic v2 BaseModel classes from JSON. Python-first.
JSON → JSON Schema
Infer a JSON Schema (Draft 2020-12) from sample JSON. Inverse of validate.
JSON ↔ CSV
Convert flat JSON arrays to CSV and back. Configurable delimiter and header.
JSON ↔ YAML
Round-trip JSON and YAML. Indent, sort-keys, document-marker toggles.
JWT Decoder
Inspect header, payload, and expiry of any JWT. 100% client-side.
Shareable URLs
Send a JSON snippet via URL. Payload lives in the fragment. Nothing on our servers.
What's missing?
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