# Today I learned about JSONL format

Fun fact, while deep diving how Claude Code works, I realised some files were stored with a `.jsonl` format! What’s this, a typo?? 😀 Of course not….

It's a text format where each LINE is a valid JSON object. So why this and not just a JSON array?!

Regular JSON - one big array

```json
[
    {"id": 1, "name": "Alice"},
    {"id": 2, "name": "Bob"}
]
```

JSONL - one object per line

```json
{"id": 1, "name": "Alice"}
{"id": 2, "name": "Bob"}
```

Why?

\- Logs and "file as database" -> just append!

\- Reading with stream: we can parse each line, one by one, immediately! A slightly different array of objects!

And much more possibilities, I’m sure!

There are some things to take in consideration:

* Not human-readable at a glance (no pretty formatting)
    
* Can't have relationships between lines easily
    
* Harder to edit manually
    
* Less tooling support than regular JSON
    

I hope you enjoyed this nugget!! Happy coding!