JSON vs CSV — Which Format Should You Use?
A practical comparison of JSON and CSV: when to use each, key differences, and how to convert between them.
Quick Comparison
| Feature | JSON | CSV |
|---|---|---|
| Structure | Hierarchical, nested | Flat, tabular |
| Human-readable | Yes (verbose) | Yes (compact) |
| Data types | String, number, boolean, null, array, object | Strings only (types inferred) |
| Nested data | Native support | Requires flattening |
| File size | Larger (key names repeated) | Smaller |
| Best for | APIs, configs, complex data | Spreadsheets, data exports, ML datasets |
| Browser support | JSON.parse() | Manual parsing or PapaParse |
| Excel support | Via Power Query | Native |
When to Use JSON
- APIs and web services (JSON is the standard)
- Config files (package.json, tsconfig.json)
- Data with nested objects or arrays
- When data types matter (booleans, numbers)
- Mobile app data storage
When to Use CSV
- Spreadsheet import/export (Excel, Google Sheets)
- Machine learning datasets (pandas, scikit-learn)
- Database bulk imports
- Simple tabular data with no nesting
- Sharing data with non-technical users
Key Differences — Deep Dive
Data types
JSON preserves native types. CSV stores everything as strings — true becomes "true", 42 becomes "42". When importing CSV, parsers must infer types.
Nested data
JSON handles nested objects natively. CSV cannot — nested keys must be flattened to dot notation (user.address.city) or the data must be restructured.
File size
CSV is typically 30–60% smaller than equivalent JSON because key names are only written once as headers, not repeated per row.
Converting Between Formats
Need to switch between JSON and CSV? Both conversions are straightforward — use the free browser-based tools below. No sign-up, no file upload to a server.
Example — Same Data in Both Formats
JSON
[
{ "name": "Alice", "age": 30, "active": true },
{ "name": "Bob", "age": 25, "active": false }
]CSV
name,age,active Alice,30,true Bob,25,false
Notice that in the CSV version, age and active are stored as plain strings. A CSV parser reading 30 or true must decide whether to treat them as numbers or booleans — JSON makes that unambiguous.
Convert between JSON and CSV instantly
Free, browser-based, no sign-up. Your data never leaves your device.