Free JSON sample files
The standard data format of web APIs: objects, arrays, strings, numbers, booleans and null. Download valid JSON test files in 10 exact sizes, from 1 KB to 10 MB, each with a checksum.
- Extension
- .json
- MIME type
- application/json
- Kind
- Text
- Category
- Data
JSON files by size
Every file below is a valid JavaScript Object Notation file of exactly the stated size. Open a file's page for its checksum and contents, and to preview it in your browser before downloading.
| File | Size | Contents | Download |
|---|---|---|---|
| 1 KB JSON samplesample-json-1kb.json | 1 KB1,024 bytes | Records: 2 | Download JSON |
| 5 KB JSON samplesample-json-5kb.json | 5 KB5,120 bytes | Records: 14 | Download JSON |
| 10 KB JSON samplesample-json-10kb.json | 10 KB10,240 bytes | Records: 29 | Download JSON |
| 25 KB JSON samplesample-json-25kb.json | 25 KB25,600 bytes | Records: 74 | Download JSON |
| 50 KB JSON samplesample-json-50kb.json | 50 KB51,200 bytes | Records: 148 | Download JSON |
| 100 KB JSON samplesample-json-100kb.json | 100 KB102,400 bytes | Records: 297 | Download JSON |
| 500 KB JSON samplesample-json-500kb.json | 500 KB512,000 bytes | Records: 1,483 | Download JSON |
| 1 MB JSON samplesample-json-1mb.json | 1 MB1,048,576 bytes | Records: 3,029 | Download JSON |
| 5 MB JSON samplesample-json-5mb.json | 5 MB5,242,880 bytes | Records: 15,103 | Download JSON |
| 10 MB JSON samplesample-json-10mb.json | 10 MB10,485,760 bytes | Records: 30,143 | Download JSON |
More JSON samples
Hand-designed files with realistic content or a specific edge case.
| File | Size | Contents | Download |
|---|---|---|---|
| Sample users JSON (array of 50 objects)sample-users.json | 14.3 KB14,664 bytes | Records: 50 | Download JSON |
| Nested JSON with every value typesample-nested-config.json | 829 B829 bytes | Root type: Object | Download JSON |
What is a JSON file?
JSON represents structured data as text using two containers, objects with named members and ordered arrays, and four kinds of value: strings, numbers, booleans and null. It grew out of JavaScript but is now language-independent.
The grammar is small and strict. There are no comments and no trailing commas, and strings must use double quotes. That strictness is what makes JSON safe to exchange between unrelated systems.
How to recognise a JSON file
No signature bytes. JSON files are identified by parsing their content.
| Extension | .json |
|---|---|
| MIME type | application/json |
| Standard | RFC 8259 and ECMA-404 |
| Encoding | UTF-8 for interchange |
| Comments | Not allowed |
| Numbers | Decimal; precision depends on the parser |
What to test for
These are the behaviours that most often go wrong when software handles JSON files.
- Most parsers read numbers as 64-bit floats, so integers above 2^53 silently lose precision. Send large identifiers as strings.
- Parsing a large document with a DOM-style parser needs several times its size in memory. Use a streaming parser or JSON Lines for big data.
- The JSON standard does not say what happens with duplicate keys, so different parsers keep different values.
Strengths of JSON
- Parsed natively by browsers and supported by every language.
- A small, strict grammar with no room for ambiguity.
Limitations of JSON
- No comments, dates or binary data.
- A whole document must normally be parsed at once, which is costly for large files.
Typical uses of JSON test files
- Mocking API responses
- Testing parsers, schema validators and serialisers
- Load-testing endpoints with large payloads
- Seeding front-end components with data
Software that opens JSON
- Every programming language and web browser
- jq, Postman and curl
- Document databases such as MongoDB and PostgreSQL JSONB
Specifications
Related
JSON sample files: questions
- What is the structure of the sample JSON?
- An object with a "records" array. Each record has strings, numbers, a boolean, a nullable field, a nested object and an array, so most deserialiser paths are exercised.
- Why is there a "padding" field?
- JSON has no comments, so a final string member is used to bring each sized file to its exact byte count.
- What is the MIME type of a JSON file?
- The MIME type is application/json. The file extension is .json.
- Is a sample JSON file the same as a dummy or example JSON file?
- Yes. Sample, test, dummy and example JSON files are different names for the same thing: a JSON file with known contents that stands in for a real one. Any file on this page will do wherever a tutorial or a test plan asks for a dummy JSON file.