What a JSON formatter does
A JSON formatter takes a JSON string — usually minified or hard-to-read — and re-emits it with consistent indentation. Most also validate syntax and flag errors at the offending character.
For most developers, formatting JSON happens in their editor (VS Code, Sublime, JetBrains) with a single keybind. The “JSON formatter tool” question usually applies when you can’t install extensions, when you’re on someone else’s machine, or when you need to format JSON you don’t want in your editor’s history.
The options
- Editor extension — fastest, stays local.
- Browser DevTools — open the Network tab, click a response, click the {} button to format. Free, local.
- jq on the command line —
jq . file.jsonfor a quick reformat. Free, local, runs offline. - jsonformatter.org / similar web tools — paste JSON, get formatted output. Uploads your JSON.
- ToolConvoy’s JSON Formatter — wait, we don’t have a dedicated JSON formatter page; what we have is the formatter built into our other JSON tools. The JSON to YAML and JSON to CSV tools both include a JSON formatter internally. They run in the browser.
Privacy note
Web-based JSON formatters paste your JSON into a text box, then send it to a server to format. The formatted output is returned. For arbitrary JSON this is fine. For sensitive JSON — API keys embedded in test fixtures, customer data exports, security response contents — that upload is a concern.
Recommendation
- In your editor: extension, fastest.
- In the browser, sensitive JSON: ToolConvoy’s JSON-to-* tools include a JSON formatter.
- Web JSON you don’t care about: any of the formatter sites.