JSON Formatter

Beautify, minify and validate JSON in your browser with LocalKit. Catch syntax errors locally—no upload, no account, ideal for API payloads and config drafts.

Interactive controls load with JavaScript. Processing stays in your browser—nothing is uploaded.

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How to use

  1. Open JSON Formatter — Go to the JSON Formatter page and wait for the editor to load.
  2. Paste JSON — Paste or type JSON into the input area. Data stays in the browser.
  3. Beautify or minify — Beautify for readability or minify for compact output; fix validation errors if shown.
  4. Copy result — Copy the output to your editor or API client.

Limits

Strict JSON only (no trailing commas / JSONC). Very large documents may freeze the tab. No hard upload size limit because nothing is uploaded.

When to use

Quickly validate, beautify, or minify JSON without pasting secrets into a third-party formatter.

When not to use

When you need JSON Schema validation, streaming multi-GB files, or jq-style query pipelines.

Privacy note

JSON never leaves your browser. Prefer this over upload-based formatters for tokens and customer data.

References

FAQ（5）

Is my JSON uploaded to a server?

No. Formatting and validation run entirely in your browser. After the page loads, you can usually keep using the tool offline.

Why does validation fail on trailing commas?

Strict JSON (RFC 8259) forbids trailing commas. Remove the last comma before } or ], then validate again.

Beautify vs minify — which should I use?

Beautify for reading and debugging; minify to shrink payloads for APIs or storage. Neither changes the data model if the JSON is valid.

Does it support large JSON files?

Yes for typical API/config sizes. Extremely large blobs may slow or freeze the tab—split the file or process in chunks if needed. There is no hard server size limit because nothing is uploaded.

Can I sort object keys?

Beautify keeps readable indentation. Key order follows the parsed object; this tool does not offer a separate “sort keys” mode.