JSON Size Analyzer

Measure a JSON payload: how many bytes it is, how much minifying would save, and how many keys, arrays and levels it contains.

JSON
Analysis
Runs locally in your browser

About the JSON Size Analyzer

Before deciding whether a payload needs pagination, compression or restructuring, it helps to know its numbers. This analyzer parses the document and reports its UTF-8 byte size, the size after minification and the percentage saved, and structural counts: objects, arrays, keys, primitive values and the maximum nesting depth.

The byte size counts UTF-8 bytes rather than characters, which is what matters for network transfer and storage limits such as a 1 MB document cap. Minified size shows how much of the payload is whitespace. Key and value counts give a sense of how many fields a client has to process, and depth flags documents that will be awkward to type or query.

For a visual breakdown of where the size goes, open the same document in the JSON Viewer and look at the item counts on each branch.

How to use

  1. Paste JSON on the left.
  2. Read the size and structure figures on the right.
  3. Use the minified size to judge whether the JSON Minifier is worth applying.

Common questions

Is the size measured in characters or bytes?
Bytes, as UTF-8. A non-ASCII character can be 2 to 4 bytes, which is what your server and network see.
Does it measure gzipped size?
Not yet. Minified size is a reasonable proxy for the uncompressed transfer size; compression typically reduces JSON by a further 70 to 90 percent.
What counts as a value?
Every string, number, boolean or null that is not an object or array. Objects and arrays are counted separately.