JSON file format
JavaScript Object Notation
JSON is the standard text format for structured data on the web: objects, lists, numbers, strings and booleans. APIs and apps use it everywhere; spreadsheets prefer CSV.
| Property | JSON |
|---|---|
| File extensions | .json |
| MIME type | application/json |
| Introduced | 2001 (RFC 8259 / ECMA-404) by Douglas Crockford |
| Type | Structured data (text) |
| How it's stored | None (plain text) |
| Keeps formatting | No — data only |
| Compatibility | Every programming language and API |
| Best for | APIs, app settings, nested data |
What is a JSON file?
JSON (JavaScript Object Notation) was popularised by Douglas Crockford in the early 2000s and is standardised as ECMA-404 and RFC 8259. It represents data as nested objects ({"key": value}) and arrays ([1, 2, 3]) in human-readable text.
JSON vs CSV
JSON can nest data and keep types (numbers, true/false, null); CSV is a flat table of text. Converting JSON to CSV flattens each record into a row — nested objects are written as JSON text in a single cell.