A JSON validator that repairs the error instead of just pointing at it
A typical JSON validator stops at the first problem, reports a line and column, and leaves you to fix it, then re-run, then find the next one. That is fine for one stray comma and miserable for a config file someone hand-edited or a payload pasted from a log.
JSON Validator checks while you type and repairs every problem it can safely interpret, all in one pass. Each change is drawn in the editor (struck through for a removal, underlined for a rewrite, highlighted for an insertion) with a short note at the end of the line, and the full list of repairs sits beside the text. Click an entry to jump to it. Nothing is changed silently, which is the usual objection to auto-fixing.
When a fault has no safe interpretation, the status bar turns to Invalid with the line number and a plain sentence about what should come next, such as "A comma or a closing bracket should come next." The checking is done by the app's own parser on your PC, not by a web page.
Common JSON errors it fixes automatically
The repair engine recognizes 18 kinds of mistake. The ones you will hit most:
- Trailing commas after the last item in an object or array
- Single-quoted strings and keys, rewritten with double quotes
- // and /* */ comments, removed
- Keys and text values with no quotes at all
- Missing commas, missing colons and missing values (filled with null)
- Python's True, False and None, written as true, false and null
- NaN and Infinity, which JSON has no way to express, turned into null
- Mismatched, extra or unclosed brackets, and a file that was cut short partway through
- Raw tabs or newlines inside a string, and unknown backslash escapes
JSON formatter and beautifier with real editing
Beautify, or Shift+Alt+F, lays the document out with an indent of 2 spaces, 4 spaces or tabs; the choice sits in the status bar and under Indent in Settings. Minified JSON pasted into an empty editor is formatted on arrival. Fold all collapses the document to its top-level keys, and any single block folds from the arrow in the gutter. The status bar always shows Ln and Col so you can match an error message from another tool.
Copy fixed JSON puts the repaired text on the clipboard, and Save as… writes it to a new file, named fixed.json unless you choose otherwise. Very large documents open read-only so scrolling stays smooth, and the fixed version can still be copied or saved.
Compare two JSON files and see the diff by key path
The Compare tab sets the open document against a second one, typed, pasted or picked with Choose file…. The result lists every value under Added, Removed or Changed with its full path, so a renamed field in a nested array is easy to spot. Reordered keys and whitespace are not counted as differences. Swap flips the sides, and Copy report puts the list on the clipboard for a pull request or a ticket.
Convert JSON to TypeScript, C# and a JSON Schema
Types & schema works out types from the sample in Check & repair: TypeScript interfaces, C# classes for System.Text.Json, and a JSON Schema. Set Root type name to the name you want at the top, then copy each result or save it.
Check a folder then runs the schema against every .json file in a directory and reports how many match, with the reason each failing file fails. Use a schema file… swaps in a schema you already maintain instead of the generated one.
