Create a sample JSON file at your chosen size
Download generated JSON records with a padding string. Test parsing and transfer sizes here, then validate the fields against your application schema.
1 MB = 1,000,000 B · 1 MiB = 1,048,576 B
Advanced: test an upload limit
Enter the byte limit above, then choose one byte below, the exact limit or one byte above. Each choice uses the same base: 10,485,760 B. Generate and download each file to test your endpoint.
JSON, built to spec.
Each file is a valid JSON document with a records array. The size you ask for is reached with a trailing string field, so the document still parses, so the result opens in jq, browser devtools, Python's json module and Node's JSON.parse. Most people generate these for testing API payload limits and request body caps.
Choose a size here
These options set the generator above. Separate size guides explain how to test a particular upload boundary.
Guides for specific upload limits
File structure and testing limits
Generated records plus a padding string remain parseable JSON. Size tests and realistic schema tests are different: validate the fields against your own application schema.
Format reference: RFC 8259.
This generator assembles the file in your browser; file content is not sent to a server. Site analytics may make network requests. Office ↔ PDF conversion uses a separate server workflow. Data processing and privacy.
Technical notes for every format · Guide to testing file upload limits
Questions
How small can a JSON file be?
About 60 bytes. Below that the format cannot carry its mandatory structure, let alone padding.
Will the file open normally?
Validate the generated fixture in your target application. Parts added for exact size may change or disappear when the file is re-saved; compatibility depends on the reader.
Can I ask for an unusual size?
Any byte count above the minimum works — for example 3,145,728 bytes (exactly 3 MB) or 27.5 MB. Drag the caliper or type the number.
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