What is JSON Formatter & Validator?
The JSON Formatter and Validator is designed for API debugging, configuration review, and readable log inspection. It parses the complete document before producing consistently indented output, and it surfaces syntax errors, unsafe integers, and duplicate keys that could otherwise be missed before data is copied into code or sent to an endpoint. Common workflows include the following. Validate an API request or response body. Turn compact logs into a structure that is easier to review. Catch bracket, quote, and comma errors before committing configuration. The page also documents input boundaries, output behavior, and practical cautions so you can review the result before putting it into an application, configuration, test, or production workflow.
When to use it
- Validate an API request or response body.
- Turn compact logs into a structure that is easier to review.
- Catch bracket, quote, and comma errors before committing configuration.
How to use it
- Paste or type JSON.
- Choose indentation and format, or minify it.
- Review any warning before copying the result.
- Load one of the realistic examples first to verify the selected options and processing direction before replacing it with your own data.
- Review the output, status message, and documented limits; copy, download, or continue only after the result matches your expectation.
Runnable examples
The “Example 1” and “Example 2” buttons load the matching inputs. They cover different structures, directions, or boundaries and can be run directly in the workspace.
Example 1
{"project":"JSONLane","release":{"branch":"develop","tools":20},"checks":["unit","e2e","build"]}Example 2
[{"id":101,"title":"Fix dark-theme contrast","done":true},{"id":102,"title":"Expand tool guidance","done":false}]Input rules
- Input must be one complete JSON value: an object, array, or scalar.
- Comments, trailing commas, single-quoted keys, and JavaScript expressions are not accepted.
- Integers outside JavaScript's safe range are rejected to prevent silent precision loss.
- Text input is counted before processing and is limited to 1,000,000 characters on this page; file modes apply the separate file limit shown in the workspace.
- Comments and trailing commas are not accepted.
Output rules
- Formatted output uses the selected two- or four-space indentation.
- Minified output is semantically equivalent single-line JSON.
- Duplicate keys trigger a warning, and the last value is retained by the standard parser.
- Output reflects only the current input, direction, and options; rerun after changing a mode or value instead of treating an earlier result as current.
- Integers outside the safe range are rejected.
Limitations and cautions
- Comments and trailing commas are not accepted.
- Integers outside the safe range are rejected.
- Duplicate keys trigger a warning and the last value wins.
How your data is handled
The document is parsed and serialized only in the current browser tab. It is not uploaded to JSONLane or written to local storage.