Help — JSON Checker

How to open JSON Checker

Click the puzzle piece in the top right of Chrome, then the pin next to JSON Checker.
Click the toolbar icon on any page. The panel opens on the right side of the window, not as a popup.

Step-by-step screenshots live on the welcome page.

You can also select JSON on a page, right-click it, and choose Check selected JSON — the panel opens with that text already loaded.

Paste — one click from the clipboard. If Chrome blocks clipboard access, focus the editor and paste with the keyboard.
Open a file — drop a .json file on the panel, or pick one. Files larger than 2 MB are refused by name (the payload is kept in local extension storage).
Type — the Check tab always shows the editor, empty or not. While it is empty you can also try a broken sample to see how repairs work.

The usual flow is Paste → Check → Fix. Format, Copy, and Clear stay on the toolbar and light up once there is text.

Offending text is underlined in the editor and marked in the gutter. Hover either for the headline, the line that actually needs changing, and a one-click repair when one exists.
Below the editor each problem is a single line: severity, line:column, headline, and repair. Open the chevron for the full explanation.
F8 / Shift-F8 step through problems from the keyboard.
After a successful repair, the Repaired JSON and Changes tabs show the result and a focused diff.

Valid payloads can still show warnings — duplicate keys, integers past 2⁵³, or invisible characters inside strings.

Everything runs on your machine. The extension declares no host permissions and makes no network requests. See the privacy policy for details.