How to Open a JSON File on Windows — and Make It Readable (Free, No Install)

What a JSON file is, and why it looks like one long line

JSON is a text format for data: names in double quotes, values after a colon, objects in curly braces and lists in square brackets. Apps use it for settings, for data you export from a service, and for what one program sends another. Because it is only text, opening a .json file cannot run anything — reading it in Notepad or a browser is safe.

Two things make it awkward on Windows. First, nothing may be set to open it. On my Windows 11 Home PC, assoc .json returned nothing and there was no default app for the extension, so double-clicking a .json file asks which app to use. Second, programs usually save JSON with every space and line break removed. My test file — an order history export with 6 orders, 74 keys and 5 levels of nesting — was 1,175 bytes on a single line. Indented by two spaces it became 116 lines and 2,156 bytes; by four spaces, 2,948 bytes. The spaces are only for people, so programs leave them out.

Way 1: open it in Edge or Chrome and tick Pretty-print

1. 1Drag the .json file onto an open Edge or Chrome window. (Or right-click the file, choose Open with, and pick Microsoft Edge.)
2. 2The text appears as it is stored — usually one long line.
3. 3Tick the Pretty-print checkbox in the bar at the top of the page.

I tried this on Edge 154 and Chrome 154 on Windows 11. Both show the checkbox above the text; Chrome labels it Pretty-print, and Edge shows the same checkbox in its own interface language (on my Korean Edge it read 예쁜 인쇄). Ticking it re-indented the file by two spaces, the same layout as the 116-line version above. Nothing is installed and the file stays on your PC.

The catch is a broken file. I added one extra comma before a closing brace — "push":false,} — which makes the JSON invalid. Both browsers still showed the Pretty-print checkbox, but ticking it did nothing: the text stayed on one line and there was no message saying why. If a file will not indent, the browser is telling you it is broken without telling you where.

Way 2: a JSON formatter that shows where it broke

A JSON formatter does what the browser checkbox does and also checks the syntax. I pasted the broken file into the JSON Formatter on this site and pressed Format. It answered Line 1, Col 1102: Expected double-quoted property name in JSON, printed the line, and put a caret under the extra comma. Python reported the same spot: column 1102.

With the comma removed, Format indented the file and showed a summary: input 1.1 KB, output 2.1 KB, 74 keys, depth 5. Minify does the reverse and puts it back on one line, and the tree view lets you fold the orders list so you can read one order at a time. You can drop the .json file onto the input box instead of pasting.

Many online formatters send what you paste to a server. This one runs in the page. I checked the network log while I used it: loading the page was the only request, and formatting and validating three times added none. That matters when the JSON is a data export with your name, email and orders in it, like my test file.

Way 3: Notepad — fine for a quick look or a small edit

Notepad opens any .json file, and it is the right tool when you only need to change one value in a settings file. It does not format or check anything, so a one-line file stays one line and a missing quote is not flagged. If you edit a file this way, keep it saved as UTF-8 and check it afterwards with the browser or a formatter: if Pretty-print still works, the file is still valid JSON.

Way 4: VS Code

If you already have Visual Studio Code, it is the most comfortable place to read and edit JSON. Its documentation gives the format command as Shift+Alt+F on Windows, or Format Document from the right-click menu. It also colours the syntax and lets you fold objects. VS Code treats settings files such as settings.json as JSON with Comments, which allows comments and tolerates trailing commas — but a normal .json file that another program reads must not have either.

Way 5: the command line — and two defaults that bite

Python ships a JSON formatter. Run it with the file name and it prints the file indented by four spaces:

python -m json.tool --no-ensure-ascii data.json

Leave out --no-ensure-ascii and every non-English character is printed as an escape: in my file the name 김민수 came out as \uae40\ubbfc\uc218. It is still the same data, but you cannot read it. On the broken file Python stopped with Expecting property name enclosed in double quotes: line 1 column 1102 (char 1101) — a precise location.

Windows PowerShell 5.1, the version built into Windows, can read JSON too, but its writer has a trap. I read the file with ConvertFrom-Json and wrote it back with ConvertTo-Json. With the default settings, the items list inside each order came out as an empty string — the products were gone, and there was no error. Adding -Depth 10 kept everything:

Get-Content data.json -Raw -Encoding UTF8 | ConvertFrom-Json | ConvertTo-Json -Depth 10

On the broken file, ConvertFrom-Json in PowerShell 5.1 said only Invalid JSON primitive: . with no line or column, so it is the least helpful way to find an error.

Which way to use

To just read a file, drag it into the browser. If it will not indent, or a program says the JSON is invalid, paste it into a formatter to get the line and column. If you work with JSON every day, VS Code is worth installing.

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