JSON Size Analyzer
Analyze JSON data size distribution with interactive treemap
JSON Input
Size Breakdown
Find out exactly which keys make your payload heavy
Slow APIs and large databases often boil down to one or two oversized fields buried in an otherwise lean payload. A size analyzer breaks the document down by byte contribution and visualizes it as a treemap, so you can see at a glance which keys deserve attention before deciding what to trim, paginate, or move out of JSON entirely.
Use the analyzer when you need to
Diagnose a slow API response
Identify the field consuming most of the payload before you optimize, paginate, or compress.
Audit a stored document
See which keys take up the most room in a NoSQL or document-database record.
Plan a payload-shrinking effort
Prioritize the highest-impact fields to remove or compress instead of micro-optimizing small ones.
How to analyze JSON size
- 1
Paste the JSON document into the editor.
- 2
Click Analyze to break the document down by key with byte counts.
- 3
Hover or click the treemap to drill into the biggest contributors.
Keep going
Minify the payload
Strip whitespace as a first cheap optimization before refactoring fields.
Visualize as a graph
Switch to graph view when relationships matter more than size.
Inspect specific fields
Drill into a heavy node in tree view to decide how to slim it down.
Format before analyzing
Pretty-print the source so the labels in the analyzer match what you expect.
Common size-analysis workflows
Identify the biggest fields and either trim, paginate, or move them out of the response body.
See which embedded subdocuments are pushing rows over storage limits.
Compare the breakdown before and after a refactor to confirm the savings landed where expected.
Related Tools
Frequently Asked Questions
It breaks down your JSON document by size, showing exactly which keys and values consume the most bytes. The interactive treemap visualization makes it easy to spot oversized fields, redundant data, or optimization opportunities.
Size is measured in bytes of the minified (whitespace-free) JSON representation. This reflects the actual payload size when transmitted over a network, which is what matters for API performance.
After identifying the largest fields, consider: removing unused fields, shortening key names for API responses, moving large binary data (images) out of JSON into separate endpoints, paginating arrays, and using GZIP compression at the server level.
For web APIs, aim to keep responses under 100KB. Mobile-first APIs should target under 50KB. Responses over 1MB should be paginated or redesigned. Use GZIP compression, which typically reduces JSON size by 70-90%.