JSON Viewer: Formatter, Tree
Validate, Prettify, Offline
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
Paste any JSON and see it as a collapsible colour-coded tree in under a second. Exact line-and-column errors when it breaks — fully offline, on your phone.
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
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Bug fixes and performance improvements.
Thanks for using the app — your feedback keeps it getting better.
Subscriptions
In-App Purchases
The developer, LEAN ASIA CO., LTD, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- LEAN ASIA CO., LTD
- Size
- 4.5 MB
- Category
- Developer Tools
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Strict Parser Lifetime $29.99
- API Tools Yearly $14.99
- Syntax Check Weekly $2.99
- Copyright
- © 2026 LEAN ASIA CO., LTD