How to open a JSON file

Three ways to open a JSON file

To open a .json file, use a text editor for raw source, Chrome for quick viewing, or a structured JSON viewer for navigation. JSON is plain text with a data structure, so treat it as data rather than an executable file.

There are three common sources: a local file from your computer, a URL that returns JSON, and text pasted or imported into a workspace. Each source has different browser permissions and troubleshooting steps.

{
  "project": "demo-api",
  "enabled": true,
  "owners": ["Lin", "Mara"],
  "limits": { "requestsPerMinute": 120 }
}

Install and check file access

Install JSON All-in-One from the public Chrome Web Store listing. The normal user path is the store listing, not development-only load-unpacked setup.

For files opened through a file:// URL, Chrome controls whether an extension can run on local files. Open the extension details page and enable Allow access to file URLs when you want direct local file navigation to be detected. JSON All-in-One exposes a shortcut to the Chrome permissions page, but the switch itself belongs to Chrome.

• Open chrome://extensions/.
• Find JSON All-in-One and open Details.
• Enable Allow access to file URLs if you want direct file:// viewing.
• Reopen the local .json file after changing the setting.

Open a small verified file

Start with a small synthetic file before trying a large export. Save the sample as demo-api.json, then open it in Chrome or through the JSON All-in-One workspace. Confirm that the root object expands, the owners array has two items, and limits.requestsPerMinute is visible.

This gives you a known-good path. If the small file opens but a large export struggles, the problem is likely input size, source shape, or a later operation rather than basic installation.

• Move from a small file to a large file

Troubleshooting by symptom

If Chrome shows raw text for a local file, first check the file URL permission. If a URL downloads instead of opening, the server may be using download-oriented headers or a media type that Chrome treats as a download. That is not the same as a viewer failing.

If another extension changes the page, use a clean profile or temporarily disable competing viewers. If the source is an HTML page containing embedded JSON, treat it as an HTML page first; ordinary HTML pages can contain JSON fragments without being JSON documents.

What file access means

File URL access lets the extension detect and read local files you open through Chrome's file:// route. It is about Chrome's local-file permission, not a paid-only workflow or a promise that every later operation has the same cost.

Core JSON-family workflows run in the browser workspace. Some optional features, such as explicitly invoked AI prompts or image fetching, have separate network boundaries and should be explained where those features are used.

Next step

Once the file opens, use the tree to understand its shape. For commented configuration, continue with JSON with comments. For a large export, continue with Open large JSON files in Chrome.