# JSON Viewer: Formatter, Tree — Validate, Prettify, Offline

> Validate, Prettify, Offline (iPhone/iPad app by LEAN ASIA CO., LTD.)

- Source: https://appshunter.io/ios/app/json-viewer-formatter-tree/id6772258771 (this page in markdown: same URL + `.md`)
- Developer: [LEAN ASIA CO., LTD](https://appshunter.io/developer/1815050814)
- Category: Developer Tools, Utilities
- Price: Free
- Age rating: 4+
- Requires: iOS 17.0 · 4 MB
- Languages: American English
- Released: 2026-05-27
- Data updated: 2026-09-21
- User reviews in markdown: https://appshunter.io/ios/app/json-viewer-formatter-tree/id6772258771/reviews.md

## What is JSON Viewer?

Paste a JSON blob — an API response, a config file, a log payload — and JSONView turns it into a collapsible, colour-coded tree the moment it lands. Validate it with an error that names the exact line and column, format or minify it, and copy it back out. Everything happens on your iPhone, offline, so your payload never touches a web tool.

Most JSON apps wrap the same lenient system parser. JSONView ships its own strict RFC 8259 engine: it preserves your key order instead of scrambling it, keeps number literals exactly as written, rejects the trailing commas other parsers silently swallow, and warns you about duplicate keys — with the position of both copies.

WHAT YOU GET
• Paste an API response and read it as a collapsible tree in under a second, with keys, strings, numbers and booleans each in their own colour
• Broken JSON tells you exactly where: "Line 14, column 27 — trailing comma before '}'" instead of a shrug
• Duplicate keys are flagged with both positions, so the bug that only bites in production gets caught on your phone
• Find any key or value in a deep payload and jump to it with its full $.path[3].to.node
• One tap copies a value, its path, or the whole document — pretty-printed or minified — to the clipboard
• Round-tripping never rewrites your data: key order survives, 1e3 stays 1e3, -0 stays -0

PERFECT FOR
• Backend and mobile developers checking an API response away from the desk
• QA engineers pinning down exactly which field broke the build
• Support and ops engineers reading the log payloads customers send in
• Anyone learning what valid JSON actually is, from a parser that explains every rejection

WHY NOT JUST A WEB FORMATTER?
Every browser JSON tool means pasting your payload — auth tokens, emails, customer records — into someone else's server. JSONView parses entirely on-device and works in airplane mode. It also opens .json files straight from Files, Mail or Slack, so you skip the copy-paste dance entirely.

PRIVATE BY DEFAULT
No network calls. No account. Your documents are parsed and stored only on your iPhone, and your saved library never leaves the device.

FULL ACCESS
JSONView Pro unlocks the complete toolkit: an unlimited saved-document library, minify to clipboard, .json file export, custom indent width, and A-to-Z key sorting. Choose a weekly plan, a yearly plan, or a one-time lifetime purchase. Weekly and yearly plans are auto-renewing subscriptions; lifetime is a single payment.

Copy a JSON payload, open JSONView, and tap Paste — the tree is already waiting.

Terms of Use: https://leanstudio.asia/terms-of-use
Privacy Policy: https://leanstudio.asia/privacy-policy
Support: support@leanstudio.asia


## Version history (last 2 releases)

### 1.1 — 2026-09-16

Bug fixes and performance improvements.
Thanks for using the app — your feedback keeps it getting better.

### 1.0 — 2026-05-27

No release notes.

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All apps by LEAN ASIA CO., LTD: https://appshunter.io/developer/1815050814

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-21.*