Question 1

What is PolyJSON?

Accepted Answer

PolyJSON is a free tool that lets you compare multiple JSON files on your local machine. Unlike traditional diff tools that only compare two files, PolyJSON supports N-way comparison — meaning you can compare 3, 4, or 5 JSON files at once. Everything runs in your browser, so no data is ever uploaded.

Question 2

How many JSON files can I compare at once?

Accepted Answer

You can compare up to 5 JSON files simultaneously. Select one file as the base and up to 4 other files as targets. The tool highlights differences between the base and each target, making it easy to see where your files diverge.

Question 3

Is my data safe? Do you upload my JSON files?

Accepted Answer

Your data is 100% safe. PolyJSON compares JSON files entirely on your local machine using client-side JavaScript. No JSON data is ever sent to any server — your files never leave your machine. There are no uploads, no server-side processing, and no data collection.

Question 4

What is config drift and how does PolyJSON help detect it?

Accepted Answer

Config drift occurs when configuration files that should be similar across environments (like Dev, Staging, and Production) gradually become inconsistent. PolyJSON helps by letting you compare all environment configs side-by-side, instantly revealing discrepancies that could cause bugs or outages.

Question 5

Does PolyJSON support large JSON files?

Accepted Answer

Yes. Since all processing happens in your browser, performance depends on your device. PolyJSON handles files with thousands of lines efficiently. For extremely large files (10MB+), processing may take a few seconds depending on your hardware.

Question 6

What kind of differences does PolyJSON detect?

Accepted Answer

PolyJSON detects additions (keys or values present in the target but not the base), removals (keys or values present in the base but not the target), and modifications (values that differ between files). Differences are shown at both the line level and word level for precise identification.

Question 7

Can I save my JSON files for later?

Accepted Answer

Yes. PolyJSON stores your JSON files locally in your browser using IndexedDB. Your saved files persist across sessions and page refreshes. Since data is stored locally, it stays private and is never uploaded anywhere.

Question 8

Is PolyJSON free to use?

Accepted Answer

Yes, PolyJSON is completely free with no hidden costs, no premium tiers, and no account required. Just open the tool and start comparing. The site is supported by unobtrusive ads.

Question 9

What browsers are supported?

Accepted Answer

PolyJSON works in all modern browsers including Chrome, Firefox, Safari, and Edge. It requires JavaScript to be enabled. For the best experience, use the latest version of your preferred browser.

Question 10

Can I use PolyJSON to compare API responses?

Accepted Answer

Absolutely. PolyJSON is great for comparing API responses from different endpoints, API versions, or environments. Paste the JSON responses into the tool and instantly see what changed between them.

Question 11

Does PolyJSON work offline?

Accepted Answer

Yes — once the page is loaded, you can compare multiple JSON files on your local machine without an internet connection. All comparison logic runs locally in your browser. You only need an initial connection to load the application.

Question 12

How is PolyJSON different from other JSON diff tools?

Accepted Answer

Most JSON diff tools only compare two files and require uploading your data to a server. PolyJSON lets you compare multiple JSON files locally on your machine — up to 5 at once — with no uploads. It also offers semantic diffing, word-level highlighting, key sorting, synchronized scrolling, and persistent local storage.

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