JSON vs CSV: when to use which

CSV is a spreadsheet's native language. JSON is an API's. Pick the wrong one and you'll waste an afternoon converting between them.

Why this matters today

Use CSV for flat, tabular data that humans will open in Excel. Use JSON when records nest, when types matter, or when a machine is on the other end.

Every format is a lie about your data — pick the one that lies the least.

In practice

Here is the part that turns theory into a habit:

• Start small — a single file, a single page, a single test.
• Measure twice. Trust the numbers, not the vibe.
• Keep an undo path. Reversible decisions buy you courage.

A note on tooling

Every tool on this site runs in your browser unless we say otherwise. That changes the trade-offs: nothing to upload, nothing to retain, nothing to leak. The downside is a small ceiling on file size and a dependency on your device's CPU — both acceptable for most editorial workflows.

Takeaway

Most data lives somewhere on the spectrum. Pick the format that lies the least about your shape.