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JSON Minifier

Minify a JSON fixture and compare its UTF-8 byte size before and after serialization. Review precision limits, malformed input, and the downloadable compact result.

Local processing

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About this tool

When to use it

Minify a JSON fixture and compare its UTF-8 byte size before and after serialization. Review precision limits, malformed input, and the downloadable compact result.

How to use it

Use this workspace when preparing a compact request fixture or checking a text payload budget. Paste JSON, select Minify JSON, and inspect the byte comparison. Copy or download devmate.min.json. Editing or clearing the input removes the previous result. For reading a nested response, use JSON Formatter instead; both tools use the same JSON parsing rules.

Guide updated 2026-09-15. Examples checked against this implementation.

Worked examples

Compact a two-field fixture

Input

{
  "project": "DevMate",
  "private": true
}

Expected output

{"project":"DevMate","private":true}

For exactly this input with LF line breaks and no final newline: 45 input bytes, 36 output bytes, and a 20.00% reduction. These are UTF-8 text sizes, not a prediction of gzip or Brotli savings.

Preserve spaces inside a string

Input

{ "label": "hello  world" }

Expected output

{"label":"hello  world"}

The two spaces inside the string remain. A regular expression that strips all whitespace would corrupt this value.

Errors and unsupported input

{"active":true,}

Remove the trailing comma. This tool accepts JSON syntax, not JavaScript object literals, comments, JSON5, or multiple JSON Lines records.

{"id":9007199254740993}

This parses, but JavaScript can round the number to 9007199254740992. Use a quoted string for an exact identifier and keep the original document.

Continue this workflow

JSON Formatter & Validator: Read and validate a nested response with indentation.
JSON Diff: Compare parsed values before adopting a changed fixture.

Format references

JSON parsing and numeric precision (MDN)

Format rules and limitations

Input is limited to 5 MiB of UTF-8 bytes. Objects, arrays, and JSON primitives are supported.

This parses and serializes JSON rather than removing whitespace token by token. Duplicate keys keep the last value; number notation, escapes, and property order can change.

Minification is not schema validation, canonical JSON for signatures, or encryption. A negative size reduction is possible when serialization expands the original notation.

Privacy and security

These tools process input in browser memory without an upload or processing API. DevMate does not save these inputs in localStorage, sessionStorage, or a share URL. Reloading starts a new workspace; browser history restoration may retain form state. Copy writes to your system clipboard and Download saves a file, which can outlive the tab. The page still loads site assets and may contact configured analytics, consent, or advertising services. DevMate analytics records route and action names, without input, output, filenames, or raw errors.

Review sensitive or production-critical output in the trusted system where it will be used.

Questions

Frequently asked questions

Why keep a minifier when the formatter can also minify?

The formatter is for inspecting a response. This workspace focuses on compact fixtures and an explicit byte comparison. Both share the same parsing and numeric limitations.

Can I use the result to recreate a signed payload?

No. Serialization can change byte representation even when values appear equivalent. Signature verification must use the original bytes required by the protocol.