Chrome extension · Free, no account

OtterJSONJSON you can actually read.
Private by design.

OtterJSON turns raw JSON into a clean tree you can search. Click the button or press Alt+Shift+J. Your JSON never leaves your computer.

Add to Chrome, it's free See how it works

Free plan forever · Optional one-time Pro upgrade · Chrome on Windows, Mac, Linux and ChromeOS

OtterJSON tree view with item counts, a search for github and the copied path $.project.repo
No accountInstall it and start. No sign-up, no email.
Runs when you clickAuto-format is opt-in.
Private by designNo ads, analytics or tracking. Your JSON stays on your device.
Pay once, if everKeep the free plan. Pro is one payment, with no subscription.

How it works

From one long line to a clean tree

No setup. Open JSON and click.

  1. Add OtterJSON to Chrome

    Install from the Chrome Web Store and pin it to your toolbar.

  2. Open any JSON

    Open an API response or a .json file, or paste JSON into the viewer page.

  3. Click or press Alt+Shift+J

    Explore the tree, search keys and values, and copy what you need.

Features

Everything you need to read JSON fast

Simple on day one, with power tools when you need them.

Free

A tree you can actually read

Fold, search and copy without scrolling through one long line.

  • Tree, Pretty and Raw views with light, dark or system theme
  • Item counts, clickable links and search across keys and values
  • Copy a value or its path, like $.data.items[0].id
OtterJSON tree view with item counts, search and copy controls
Free

Exact, and honest about problems

OtterJSON shows your data as it is.

  • Big numbers keep every digit
  • Duplicate keys are flagged
  • Clear errors with line and column
Raw JSON turned into a tree with one click or Alt+Shift+J
Pro

Compare, query and export

Find what changed and pull out just what you need.

  • Compare with the previous response, pasted JSON or a file
  • JSONPath queries and regex search
  • Table view with sort, filter and CSV export
OtterJSON Pro table view, JSON diff and JSONPath query
Pro

Types, decoding and repair

Turn JSON into code and fix almost-JSON.

  • Generate TypeScript, Go or Python types, or convert to YAML or CSV
  • Decode JWTs, Base64, URL-encoded text and timestamps. JWT signatures are not verified.
  • Auto-repair almost-JSON and see what was fixed
OtterJSON Pro decoding a JWT, generating types and repairing JSON

And everything else you'd expect

Keyboard first Free

Alt+Shift+J to format, / to search, T, P and R to switch views.

JSONP and JSON Lines Free

Read NDJSON and JSONP responses.

Copy, minify, save Free

Copy formatted or minified JSON, or save it as a file.

Paste or drop Free

Open JSON from anywhere in the viewer page.

Auto-format Free

Opt in to format JSON pages as soon as they open.

History and snippets Pro

Opt-in and stored on your device.

7 extra themes Pro

Pick the look that's easiest on your eyes.

Custom shortcuts Pro

Set keys for the tools you use most.

Privacy

Your JSON stays yours

OtterJSON processes JSON in your browser, with no analytics or remotely hosted code. Your JSON is never sent to us or to payment providers.

  • No account to start, no tracking or ads
  • Click-to-format reads the tab you choose. Optional auto-format requires broader site access.
  • The free extension makes no network requests. Pro purchases and license checks never include your JSON.
Read the privacy policy
Raw JSON in the browser compared with OtterJSON
Your workflow Raw JSON in the browser OtterJSON
Reading it One long line A tree you can fold
Finding a value Search through text Search and copy the path
Broken JSON Hard to spot Line and column
Account Not needed Not needed to format
Your data Stays in the tab Stays on your device
Price No cost Free, or pay once for Pro

Made for developers

For the JSON you look at every day

API responses

Read an endpoint's output without leaving the tab.

Webhooks and logs

Search JSON Lines and NDJSON.

Config files

Find errors with line and column.

Tokens Pro

Decode a JWT and see when it expires.

Before and after Pro

See what changed between responses.

Data exports Pro

Turn an array into a table and export CSV.

Pricing

Start free. Upgrade once if you need more.

No subscription and no surprise charges. The free plan is yours to keep.

Free

$0forever

Everything you need to read JSON.

  • Click or shortcut to format, optional auto-format
  • Tree, Pretty and Raw views, light/dark/system theme
  • Search, item counts and clickable links
  • Copy path or value
  • Exact big numbers and duplicate key warnings
  • Errors with line and column
  • JSONP and JSON Lines / NDJSON
  • Copy, minify, save, paste-or-drop viewer
Add to Chrome

Pro

$9.99one-time payment

Pay once and it's yours. No subscription.

  • Everything in Free, plus:
  • Compare JSON with a previous response, pasted JSON or a file
  • JSONPath queries, regex search and filtered tree
  • Table view with sort, filter and CSV export
  • YAML and CSV conversion; TypeScript, Go and Python types
  • Decode JWT, Base64, URL-encoded text and timestamps
  • Auto-repair almost-JSON
  • Local history and snippets
  • 7 extra themes and custom shortcuts
Add to Chrome, then upgrade

Upgrade from inside OtterJSON. Stripe handles checkout through ExtensionPay. Restore Pro on another computer using your purchase email.

Compare all Free and Pro features
OtterJSON Free and Pro features
Feature Free Pro
Click or shortcut to format, optional auto-format Included Included
Tree, Pretty and Raw views, light/dark/system theme Included Included
Search, item counts and clickable links Included Included
Copy path or value Included Included
Exact big numbers and duplicate key warnings Included Included
Errors with line and column Included Included
JSONP and JSON Lines / NDJSON Included Included
Copy, minify, save, paste-or-drop viewer Included Included
Compare JSON with a previous response, pasted JSON or a file Not included Included
JSONPath queries, regex search and filtered tree Not included Included
Table view with sort, filter and CSV export Not included Included
YAML and CSV conversion; TypeScript, Go and Python types Not included Included
Decode JWT, Base64, URL-encoded text and timestamps Not included Included
Auto-repair almost-JSON Not included Included
Local history and snippets Not included Included
7 extra themes and custom shortcuts Not included Included

FAQ

Questions, answered

Is OtterJSON free?

Yes. Formatting, tree view, search and copy path are free with no account or time limit. Pro adds compare, JSONPath, tables, types, decoding and repair.

Does OtterJSON send my JSON anywhere?

No. JSON is processed locally, including with Pro.

Does it make any network requests?

The free extension makes none. Buying or restoring Pro uses ExtensionPay to check your license. The check never includes your JSON or browsing activity. See the privacy policy.

Why does Chrome mention extensionpay.com when I install it?

ExtensionPay handles Pro licensing. Its purchase confirmation script runs on extensionpay.com.

Does it need access to all my sites?

Not by default. It reads the tab you choose to format. When you enable auto-format, Chrome asks for access to all sites. You can turn it off any time.

Will big numbers be rounded?

No. Large IDs keep every digit, and duplicate keys are flagged.

Can I open local .json files?

Yes. Enable "Allow access to file URLs" in the extension details, or paste or drop the file into the viewer.

Is Pro a subscription?

No. Pro is a one-time purchase. See Pricing.

Does Pro work offline?

Yes. Your Pro status is saved on your computer after purchase.

How do I use Pro on a new computer?

Install OtterJSON, open Options and choose "Already paid? Restore" or use "Restore purchase" from a Pro tool. Use the email you purchased with.

Where doesn't it work?

Chrome blocks extensions on chrome:// pages, the Chrome Web Store and other extensions' pages.

I need help or have an idea.

Email support@espinallab.com.

Let the otter tidy up your JSON

Click once and read it like a tree.

Add to Chrome, it's free