JSON represents values such as objects, arrays, strings, numbers, true, false and null. Property names and strings use double quotes. A compact API response can be valid but difficult to scan. Formatting adds indentation and line breaks so nested values are easier to follow without changing the intended data structure.
Use the U18-CHAN Json Formatter alongside this guide.
Format a small sample first
Paste the JSON into the formatter and choose two or four spaces of indentation. Run the tool, inspect the output and download the JSON file or copy it to your editor. If the parser reports an error, check for single quotes, trailing commas, missing commas and unclosed brackets. Comments are not part of standard JSON.
Separate syntax from application rules
A successful parse confirms JSON syntax. It does not confirm that a required field exists, that a date uses the expected format or that an API will accept the request. Use the receiving application’s schema and validation rules to check those requirements. JSON Validator gives the same syntax-focused check without presenting a full formatted output.
Be careful with large integers
The tools parse numbers using JavaScript. Very large integer identifiers beyond the safe integer range can lose precision during parsing and serialization. If exact identifiers matter, follow the API’s supported string representation or use a parser designed to preserve those numeric values. Formatting should never silently become a data migration step.
Inspect and save deliberately
Use JSON Viewer for a collapsible tree and JSON Minifier when you need compact output. Do not put access tokens or private responses into a shared device. Built-in processing is local to the browser tab, but clipboard contents and downloaded files remain on your device. Keep the original response when the data is important.
A simple finishing check
Keep the original input, inspect the result and confirm that it fits the destination where you plan to use it. If a result looks unexpected, try a small harmless example and read the limitations on the tool page before proceeding.
Browse all free U18-CHAN tools to continue, or report a problem with a clear description of the tool and browser.