JSON Viewer Firefox

JSON Viewer

A beautiful, customizable JSON/JSONP viewer and highlighter. Open-source fork: github.com/Lysak/json-viewer

Features & Capabilities

It is a Chrome extension for printing JSON and JSONP.

Notes:

  • This extension might crash with other JSON highlighters/formatters, you may need to disable them
  • To highlight local files and incognito tabs you have to manually enable these options on the extensions page
  • Sometimes when the plugin updates chrome leaves the old background process running and revokes some options, like the access to local files. When this happen just recheck the option that everything will work again
  • Works on local files (if you enable this in chrome://extensions)

Features

  • Syntax highlighting
  • 27 built-in themes
  • Collapsible nodes
  • Clickable URLs (optional)
  • URL does not matter (the content is analysed to determine if its a JSON or not)
  • Inspect your json typing "json" in the console
  • Hot word json-viewer into omnibox (type json-viewer + TAB and paste your JSON into omnibox, hit ENTER and it will be highlighted)
  • Toggle button to view the raw/highlighted version
  • Works with numbers bigger than Number.MAX_VALUE
  • Option to show line numbers
  • Option to customize your theme
  • Option to customize the tab size
  • Option to configure a max JSON size to highlight
  • Option to collapse nodes from second level + Button to unfold all collapsed nodes
  • Option to include a header with timestamp + url
  • Option to allow the edition of the loaded JSON
  • Option to sort json by keys
  • Option for C-style braces and arrays
  • Scratch pad, a new area which you can type/paste JSON and format indefinitely using a button or key shortcut. To access type json-viewer + TAB + scratch pad ENTER

This plugin is open source https://github.com/tulios

Bugs and suggestions https://github.com/tulios/json-viewer/issues

Contributors Thiago Pontes (@thiagopnts) @bluec0re @North101 Ben Hollander (@benhollander) Mehdi Bahrami (@mehdibahraami) Reimund Trost (@reimund) Ben van Enckevort (@benvan)

License MIT License

Any questions tweet me @tulios

User Growth & Download Statistics

Manifest V3 Add-on
By:
Dmytrii Lysak
Daily users:
32
Version:
0.19.2025.1218 Last updated: 2025-12-21
Version code:
6101826
Creation date:
2025-12-18
Risk:
Moderate risk impact Moderate risk likelihood
Permissions:
Host permissions:
  • *://*/*
  • <all_urls>
Content scripts matches:
  • <all_urls>
Size:
1.01MB
Email:
dm*****@gmail.com
URLs:
Website
Full description:
See detailed description
Source:
Firefox Add-ons Store
Data ingested on:
2026-06-03
Compare stats and ranking:

Contact the developer

Chrome-Stats does not own this Firefox add-on. Please use these information below to contact the Firefox add-on developer.
Developed by:
Dmytrii Lysak
Firefox Add-ons Store
https://addons.mozilla.org/firefox/addon/json-viewer-dev/
Email:
dm*****@gmail.com
Website:
https://github.com/Lysak/json-viewer/issues

Is JSON Viewer Safe?

Risk impact
Risk impact measures the level of extra permissions an extension has access to. A low risk impact extension cannot do much harms, whereas a high risk impact extension can do a lot of damage like stealing your password, bypassing your security settings, and accessing your personal data. High risk impact extensions are not necessarily malicious. However, if they do turn malicious, they can be very harmful.

JSON Viewer requires a few sensitive permissions. Exercise caution before installing.

Risk impact analysis details
  • Critical Allows access to all websites, posing a significant security risk as it can monitor and modify data from any visited site.
  • High ******* ******* **** *** ****** ***** *** ***** ** ******* **** ********* ********* ** * *********** *****
  • Low ****** ***** ** ******* ****** ********** **** ** ** ******** ******* ** **** ***** *************
Risk likelihood
Risk likelihood measures the probability that a Firefox add-on may turn malicious. This is determined by the publisher and the Firefox add-on reputation on Firefox Add-ons Store, the amount of time the Firefox add-on has been around, and other signals about the Firefox add-on. Our algorithms are not perfect, and are subject to change as we discover new ways to detect malicious extensions. We recommend that you always exercise caution when installing a Firefox add-on.

JSON Viewer is probably trust-worthy. Prefer other publishers if available. Exercise caution when installing this add-on.

Risk likelihood analysis details
  • High This extension has low user count. Unpopular extensions may not be stable or safe.
  • Medium **** ********* *** ***** ** *** **** * ******* *** ********** *** *** ** ****** ** *****
  • Low **** ********* *** ******* **** **** * ****** **** ***** ******** *** **** ****** ** ** ****** *** *****
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