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Sealpaste

JSON Minifier

Remove whitespace and line breaks from JSON to make it as small as possible. Values stay exactly the same.

Mode

Input JSON

Minified

How to use it

  1. 1Paste formatted JSON or open a file.
  2. 2The minified result appears on the right with the size before and after.
  3. 3Copy it, or download it as a .json file.

Private by design

Everything runs in this browser tab. Your input is never uploaded, logged or saved on a server, and there are no public "recent" pages. Close the tab and it's gone.

How we keep it private

Examples

Minify a config

Input

{
  "name": "web",
  "replicas": 3,
  "ports": [80, 443]
}

Output

{"name":"web","replicas":3,"ports":[80,443]}

When to minify JSON

Minified JSON is smaller to send and store: request bodies, environment variables, fixtures in tests, or values pasted into a single-line field.

If the JSON is served over HTTP, gzip or Brotli compression already removes most of the whitespace cost, so minifying matters most where compression is not used.

Frequently asked questions

Is my JSON sent to a server?

No. Parsing and formatting run in your browser (large inputs in a background Web Worker). Nothing is uploaded, logged or stored, so API responses with tokens or customer data stay on your machine.

Why do my big numbers stay exact here?

Many formatters use JSON.parse, which turns 12345678901234567890 into 12345678901234567000. This tool keeps every number exactly as written, so 64-bit IDs and prices with trailing zeros are not changed.

How large a file can I format?

Up to 10 MB of text works well in a modern browser. The work runs off the main thread, so the page stays responsive.