Test jq filters without installing jq; runs on a server.
On this page
Scores
Updated
Out of 5, from what each tool does. The reasons are in the reviews below.
Tool
Privacy
Features
Price
Aarrange
5
4
5
Browser DevTools
5
2
5
JSON Editor Online
4
4
4
jsonhero.io
3
3
5
JSONLint
1
2
5
Curious Concept
1
2
5
jqplay.org
1
1
5
Why developers are switching away from JSONFormatter.org
In November 2025, security researchers at watchTowr Labs showed that JSONFormatter.org and CodeBeautify had exposed thousands of secrets that developers had pasted into them. The sites were not hacked. Both have a Save button that turns your input into a shareable link, and a public Recent Links page that lists those saved links for anyone to browse.
Using only that public feature, the researchers collected more than 80,000 saved submissions: five years of JSONFormatter content and one year of CodeBeautify content, over 5 GB in total. Among them were passwords, Active Directory credentials, database credentials, cloud access keys, repository tokens and private keys, from banks, government bodies, healthcare and other sectors.
Saved JSON on either site? Rotate the secretswatchTowr planted fake AWS keys on the sites, and someone tried to use one within 48 hours. Others were already harvesting the saved data. If you ever saved JSON with a key, token or password on JSONFormatter.org or CodeBeautify, treat it as exposed and rotate it.
The lesson goes beyond one feature. Once your data sits on someone else's server, it is only as safe as their storage and their sharing settings. A tool that does all its work in your browser and never uploads your input cannot leak it this way.
Below, we compare seven alternatives to JSONFormatter.org on features, privacy and developer experience, with particular attention to whether your data stays on your machine.
Quick comparison: 7 JSONFormatter.org alternatives at a glance
Aarrange: privacy first, with the widest feature set
JSON Editor Online: tree view exploration
JSONLint: quick validation
jsonhero.io: visual JSON exploration
Curious Concept: RFC compliance checking
jqplay.org: jq filter testing
Browser DevTools: built-in convenience
Detailed reviews
We tested each tool with real-world JSON, from small config files to large API responses of more than 50,000 lines. Here is how they did.
01
Aarrange
Everything runs in your browser; a young site with a small community.
Every tool runs in your browser, so your data is never uploaded
23 free tools: JSON plus YAML, TOML, CSV, XML, Markdown, HTML, CSS and SQL formatters, and more
JSON Schema validation (Ajv, drafts 07, 2019-09 and 2020-12) and JSON to YAML and XML conversion
Errors point to the exact line and column, with a hint on how to fix them
No sign-up and no ads
Cons
Newer site with a smaller community
No dark mode or editor themes
Every tool on Aarrange runs in your browser. Your JSON is not sent to a server, and there is no save-to-server link that could end up on a public list. If you regularly paste API keys, customer records or internal configs into a formatter, that matters more than any feature.
The JSON Validator finds the exact line and column of an error and suggests a fix, then formats, minifies or sorts keys. A Tree tab lets you fold and explore nested data. The JSON Schema Validator uses Ajv with drafts 07, 2019-09 and 2020-12, and can generate a schema from your data or sample data from a schema.
Beyond JSON, the same site has converters to YAML and XML and formatters for YAML, TOML, CSV, XML, Markdown, HTML, CSS and SQL, which cuts down on bookmark clutter. 23 tools in all, free, with no sign-up and no ads. The trade-off: it is a small, young site, and there is no dark mode or theme picker.
Nothing beats DevTools for privacy: everything stays on your machine. Chrome's Network tab renders JSON responses as collapsible trees with path copying, which is handy when debugging API calls.
But it is a viewer, not an editor. You cannot paste arbitrary JSON for formatting, customize indentation or convert between formats. Use it alongside a dedicated formatter rather than instead of one.
Excellent tree view for exploring nested structures
Client-side processing in the free tier
JMESPath query support for filtering large JSON
Clean, modern interface
Cons
Some features locked behind a paid plan
Slower with very large files (10 MB and up)
Cloud sync in the paid tier sends data to servers
JSON Editor Online packs a lot into one interface: code on the left, tree on the right. That dual-pane layout makes nested objects easy to understand at a glance.
The free version handles most everyday tasks and processes data locally in your browser. You need the paid plan for cloud storage, sharing or advanced transformations, and that tier does store data on a server. Stick to the free version for sensitive data and your JSON stays local.
Detects and renders dates, URLs, images and colors
Open source (GitHub)
Great for exploring unfamiliar API responses
Cons
Uploads JSON to their servers for shareable links
No formatting or beautifying output
Read-only, so you cannot edit the JSON
JSON Hero does not try to be a formatter. It is a visual explorer for JSON, and it is good at that. The column view, inspired by the macOS Finder, works well for deeply nested objects, and it detects types and renders image previews, dates and URLs inline.
The trade-off: you cannot modify or format your JSON, it is read-only. And if you share a link, your data goes to their servers. Great for poking around an unfamiliar API response; for daily formatting you will want another tool alongside it.
05
JSONLint
Quick validity check; sends your JSON to a server.
JSONLint has been around for over a decade and still does one thing: validate JSON. Paste, click, done. Error messages are clear and point you to the problem line.
The downside is that your JSON is sent to a server for validation. That is fine for public API responses, but risky for anything with credentials or personal data. There is no formatting customization and no conversion. Good as a quick sanity check, not as an everyday tool.
06
Curious Concept
Checks JSON against RFC standards; dated and server-side.
Server-side processing, so your data is sent to their servers
Dated interface that has not been updated in years
No tree view, conversion or modern features
Curious Concept's JSON Formatter has been around since 2007, and its main selling point is RFC compliance. You can check JSON against RFC 4627 or RFC 8259, which helps when debugging compatibility with older parsers.
Outside of that it is a basic formatter with server-side processing. The interface has not been updated in a while, and there is no tree view or conversion. Useful if you specifically need RFC validation, limited beyond that.
07
jqplay.org
Test jq filters without installing jq; runs on a server.
No formatting, validation or general-purpose features
jqplay does one thing: it lets you test jq expressions in a browser. If you build data pipelines or write shell scripts that parse JSON, that is useful. Type a filter and watch the output update live.
The catch is that jq runs on their server, so your JSON is sent to their infrastructure. It is not a general-purpose formatter, but if you want to prototype jq filters without installing anything, it is the best-known option.
Search interest
How often people search Google for each tool by name, month by month over five years. It shows which names people know, not how many people use the tool. Google compares at most five names at a time, so this chart joins two searches that share JSON Editor Online.
Source: Google Trends, worldwide web search, Oct 2021 to Oct 2026 (Oct 2026 is a part month). This is search interest, not visits: 100 is the busiest month of any name in this chart, and the table shows averages. Fetched 2026-10-14.
Full feature comparison
Here is every feature across all seven alternatives: full support, partial support, or missing.
Feature
Aarrange
Browser DevTools
JSON Editor Online
jsonhero.io
JSONLint
Curious Concept
jqplay.org
Core features
Format / beautify
Yes
No
Yes
No
Yes
Yes
No
Validate
Yes
No
Yes
No
Yes
Yes
No
Minify
Yes
No
Yes
No
No
No
No
Tree view
Yes
Yes
Yes
Yes
No
No
No
Conversion
JSON to YAML
Yes
No
No
No
No
No
No
JSON to XML
Yes
No
No
No
No
No
No
JSON Schema validation
Yes
No
Partly
No
No
No
No
Editor features
Syntax highlighting
Yes
Yes
Yes
Yes
Partly
No
Yes
Dark mode
No
Yes
Yes
Yes
No
No
No
Customizable themes
No
Partly
Partly
No
No
No
No
Keyboard shortcuts
Yes
Yes
Yes
Partly
No
No
Partly
Privacy and security
Client-side processing
Yes
Yes
Yes
Partly
No
No
No
No data sent to server
Yes
Yes
Partly
No
No
No
No
Works offline
Partly
Yes
No
No
No
No
No
Additional
Multiple languages
Yes
No
No
No
No
No
No
Free (no limits)
Yes
Yes
Partly
Yes
Yes
Yes
Yes
Privacy audit: client-side vs server-side
Where your data is processed matters more than any other feature. Here is how each tool handles it.
Client-side tools: your data stays localAarrange and Browser DevTools process everything in your browser. No network requests carry your data, and you can check this yourself in the DevTools Network tab while you use them. JSON Editor Online also processes locally in the free tier, though the paid tier adds cloud storage.
Hybrid tools: partial server involvementjsonhero.io shows your data locally, but stores it on a server for shareable links. If you only paste and view without sharing, your data stays local.
Server-side tools: your data leaves your machineJSONLint, Curious Concept and jqplay.org all send your JSON to their servers. What happens to it next depends on how they store and share it, as the JSONFormatter.org case showed. Do not paste API keys, tokens or credentials into these tools.
If you handle production data, internal APIs or anything that might contain secrets, client-side processing is a requirement, not a preference. The 2025 exposure showed how easily data stored by an online tool can end up in public view.
Our verdict
For a direct JSONFormatter.org replacement, Aarrange covers the most ground. Every tool runs in your browser, it handles many formats beyond JSON, it has a tree view, and nothing is behind a paywall.
If you want a side-by-side code and tree editor with queries, JSON Editor Online pairs well with it. For jq prototyping, jqplay.org is the best-known online option, but do not paste production secrets into it.
After the 2025 exposure, defaulting to client-side tools is common sense. Your JSON formatter should not be a security risk.
FAQ
Was JSONFormatter.org hacked?
No. According to watchTowr Labs, the researchers used the sites' own features. Saved JSON got a shareable link, and a public Recent Links page listed those links, so anyone could browse what other people had saved.
What data was exposed?
More than 80,000 saved submissions, over 5 GB, from five years of JSONFormatter and one year of CodeBeautify. They included passwords, Active Directory and database credentials, cloud access keys, repository tokens and private keys.
What should I do if I saved JSON on JSONFormatter.org or CodeBeautify?
Treat any key, token or password in it as exposed and rotate it. Researchers saw someone try a planted fake AWS key within 48 hours, so others were already collecting the data.
Which JSONFormatter.org alternatives keep my data in the browser?
Aarrange and Browser DevTools process everything locally, and JSON Editor Online does in its free tier. JSONLint, Curious Concept and jqplay.org send your JSON to their servers; jsonhero.io stores it on a server when you share a link.
Is Aarrange free?
Yes. All 23 tools are free, with no sign-up and no ads, and every one runs in your browser. The JSON Validator formats, minifies, sorts keys and has a tree view.
Aarrange
Browser DevTools
JSON Editor Online
jsonhero.io
JSONLint
Curious Concept
jqplay.org
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