Browser extension

The CurlyJSON extension formats JSON right in the browser tab: open an API URL and read the response as a tree instead of one long line of text.

Add to Chrome — free · works in Chrome, Edge, Brave and other Chromium browsers. In Edge, allow extensions from other stores when it asks.

Format a page

Open a page that shows JSON, click the CurlyJSON icon in the toolbar, then Format this page.

To format JSON pages as they open, turn on Format JSON pages automatically in the same popup. The browser asks for permission to read pages first; the extension only changes pages whose content is JSON.

Three views

• Tree — collapsible, with item counts. Long lists show 500 items at a time, with Show more.
• Formatted — indented JSON with colours.
• Raw — the text exactly as the server sent it.

Switch with the tabs, or press 1, 2 or 3. Expand all and Collapse work on the tree.

Search

Press / (or Ctrl+F / ⌘F) and type. Search finds keys and values anywhere, even inside collapsed branches, opens the levels down to each match and shows “1 of 12”. Enter goes to the next match, Shift+Enter to the previous one, Esc clears it. Press Ctrl+F again in the search box for the browser’s own find.

Copy, links and saving

• Hover a row and click its path (like $.items[2].price) to copy it, or copy to copy the value.
• URLs in your data are links.
• Copy copies the formatted JSON; Save downloads it as a file named after the page (for example users.json).
• Big numbers stay exact: 12345678901234567890 is never rounded.

Big files

A 10 MB response opens in about a second, and files up to 50 MB work. Only the rows you can see are drawn, so scrolling stays smooth.

Secrets

If the JSON contains likely API keys, tokens or passwords, a yellow ⚠ 3 secrets · Hide button appears. Click it to mask them in every view (sk_live_••••••), and again to show them. See Hiding secrets for what’s detected.

Open in CurlyJSON

Open in CurlyJSON opens the data in the full website tools (diff, jq, JSON Schema, converters). The data travels after the # in the link, which browsers never send to a server. If it contains secrets, the extension asks first and offers Hide and open. Very large documents are copied to your clipboard instead, to paste on the site.

Also handled

• JSON served as text/plain, and NDJSON / JSON Lines (one value per line, shown as a list)
• Pages with strict Content Security Policies
• Invalid JSON: a banner says what’s wrong, and the Raw view marks the position
• Light and dark themes follow your system setting

Privacy

The extension has no tracking, no analytics and makes no network requests. Your JSON never leaves the browser. It needs no website access to install; automatic formatting asks for it only when you turn it on. Details: privacy policy.