JSON Size Analyzer
Break a document down field by field to find the weight.
Opens the editor with the sample loaded. Click Size to break the document down by property — all in your browser.
When an API response is slow or a document is unexpectedly large, the question is always “what is taking up all the space?” A size analyzer answers it by breaking a JSON document down property by property, so you can see which fields, arrays and nested objects account for most of the bytes.
Why analyze JSON size
- Trim heavy responses. Find the one field — often a base64 blob, a giant array, or a duplicated sub-object — that dominates the payload.
- Debug slow APIs. Payload size is a common, overlooked cause of slow requests. Measure it before you optimize.
- Plan a schema. Understand which parts of a document are expensive before you design storage or caching around it.
How it works here
Paste a valid JSON document and open the Size analyzer. It walks the structure and reports the contribution of each top-level property and nested branch, so the expensive parts rise to the top. Instead of guessing, you get a ranked view of where the weight actually lives.
Pair it with minify
Size analysis tells you which fields are heavy; minifying tells you how much pure formatting overhead you can remove for free. Use them together: strip whitespace with the JSON minifier, then analyze what real data remains.
Runs locally
The analyzer never uploads your JSON. Everything is computed in your browser, so production payloads are safe to measure here.
Frequently asked questions
How do I find which field makes my JSON large?
Paste the JSON and open the Size analyzer. It breaks the document down by property and ranks the branches, so the heaviest fields are easy to spot.
Does the size analyzer upload my data?
No. The analysis runs entirely in your browser and nothing is sent to a server.
What usually makes a JSON payload heavy?
Most often a large embedded string (like base64-encoded content), a big array of records, or deeply duplicated sub-objects. The analyzer surfaces which one it is.
Related tools
Prefer to start from scratch? Open the JSON editor and paste your own data — everything runs locally in your browser.