Format, validate, and minify JSON for APIs and development
JSON is the standard format for APIs and config files. Raw JSON is often minified—hard to read. A JSON formatter adds indentation, validates syntax, and can minify for production. Use it when debugging API responses, inspecting configs, or preparing JSON for storage.
Most "invalid JSON" bugs come down to a handful of repeat offenders: a trailing comma after the last item in an array or object (valid in JavaScript object literals, invalid in strict JSON), single quotes instead of double quotes around strings and keys, an unquoted key like {name: "x"} instead of {"name": "x"}, or a stray comment — JSON has no comment syntax at all, unlike JSON5 or JSONC. A formatter surfaces the exact line and character where parsing broke, which is faster than bisecting a 2,000-line API response by eye.
Formatting (pretty-printing) adds indentation and line breaks so a human can scan the structure — use it while debugging, writing documentation, or reviewing a config file in a pull request. Minifying strips all non-essential whitespace to shrink payload size — use it right before an API response ships or a config file gets bundled, where every byte counts toward transfer time. Keep the pretty-printed version in source control and minify only at build or response time; committing minified JSON makes diffs unreadable.
For a single paste-and-check, a browser tool is the fastest path. For validating JSON inside a CI pipeline or against hundreds of files, reach for a CLI: jq empty file.json validates syntax and exits non-zero on failure, and python -m json.tool does the same with a built-in interpreter. For validating that a JSON document matches an expected shape (not just that it parses), that's a job for a schema validator like JSON Schema, which is a different tool from a formatter entirely — formatting confirms syntax, schema validation confirms structure.