JSON Formatter App is a professional, privacy-first JSON toolkit that runs entirely in your browser — your data never leaves your device. There is no upload step, no account, and no server-side processing: every operation happens locally in the tab, which makes it safe even for private API responses, configuration files with credentials, or customer data you cannot paste into cloud tools.
Core features
- Formatter / validator / beautifier / minifier with large-file support. The validator names 11 error categories (trailing commas, single quotes, unquoted keys, …) with exact line and column positions and one-click auto-repair.
- Converters: JSON to/from CSV, XML, YAML, TOML, Base64 — with nested-value flattening, UTF-8 BOM for Excel, and single-object transposition.
- Code generation: turn any JSON sample into typed models for Java, C#, Python, Rust, Go, and TypeScript.
- jq playground: real jq compiled to WebAssembly — map, select, sort_by, group_by and object construction with live preview as you type.
- JSONPath tester with real-time evaluation, match counts, and honest error reporting.
- JSON Schema tools: validate with Ajv (draft 2020-12) and generate a schema from a sample with type inference, required-field detection, and array-shape merging.
- JSON diff that pairs array items by identity (id/key/_id) instead of index, so one edit does not cascade into dozens of false changes.
- Tree & table views with in-tree search, copy value/path, column sorting, and row filtering — all non-destructive.
- Secrets scanner that warns you before pasting data that looks like API keys or tokens.
Why client-side matters
Most online formatters POST your text to a server. This one is a static site: open DevTools and watch the Network tab — requests stay at zero after load. That design also keeps it fast and free.
Dark mode included. No signup, no ads, no limits — free forever.
