"Should I use JSON or CSV?" I'm asked often this question which is nearly every time "it depends." Both formats store data however, they're created for totally different situations. Let me go through how each of them makes sense.
CSV: The Simple Workhorse
CSV is a shorthand for Comma-Separated Valuables CSV is a literal translation of it's. Values in rows, data that are separated using commas. You could also write one with your fingers if you wanted to.
name,age,city
John Doe,30,New York
Jane Smith,25,Los Angeles
That's it. No fancy syntax, no curly braces, just data with commas between values.
What I Like About CSV:
- You can open it in Excel, Google Sheets, or any text editor
- File sizes are tiny - there's barely any overhead
- Anyone can understand what they're looking at
- Dead simple to parse programmatically
- Great for data that fits in a table - rows and columns
JSON: The Flexible Powerhouse
JSON (JavaScript Object Notation) can handle more complex structures. You can nest things inside other things, have lists within objects, the whole deal.
{
"users": [
{ "name": "John Doe", "age": 30, "city": "New York" },
{ "name": "Jane Smith", "age": 25, "city": "Los Angeles" }
]
}
What I Like About JSON:
- Data can be nested - objects within objects, arrays within arrays
- Every programming language knows how to read it
- Keys tell you what the data means - it's self-documenting
- Numbers, strings, booleans, nulls - real data types, not just text
- It's what APIs speak
The Real Differences
| What Matters | CSV | JSON |
|---|
| Data shape | Flat table only | Any structure |
| Non-techie friendly | Very | Somewhat |
| File size | Compact | Bigger (all those quotes and braces) |
| Data types | Everything's text | Numbers, strings, booleans, null |
| Nesting | Nope | Absolutely |
When CSV Is the Right Call
- Sharing data with Excel users: Your coworker who lives in spreadsheets will thank you
- Simple lists: Contact lists, inventory, any "rows of things with the same columns" data
- Database dumps: Exporting data from SQL databases
- Data science work: pandas, R, and similar tools love CSV
- Size matters: When you're emailing files or storage is limited
When JSON Makes More Sense
- APIs: This is JSON's home turf - almost every API speaks JSON
- Config files: Settings for apps and tools
- Nested data: User profiles with addresses, orders with line items, anything with sub-objects
- Backend-facing frontend communication: JavaScript loves JSON (it's in the name)
- NoSQL databases: MongoDB, CouchDB, etc. are all JSON through the entire way
Converting Between Them
CSV to JSON
Each row becomes an object, and your header row becomes the keys. Pretty straightforward:
You start with:
name,email,role
John,john@example.com,admin
Jane,jane@example.com,user
You end up with:
[
{ "name": "John", "email": "john@example.com", "role": "admin" },
{ "name": "Jane", "email": "jane@example.com", "role": "user" }
]
JSON to CSV
It's more difficult since you're changing 3D form 3D shape into 2D. Our converter handles it by:
- Flattening nested stuff with dot notation (user.address.city becomes a column)
- Turning arrays into JSON strings (yes, JSON inside CSV - it's not elegant but it preserves data)
- Making columns for every unique key it finds
- Escaping commas and quotes properly so nothing breaks
Practical Tips
If You're Making a CSV
- Put headers in the first row - always
- If the value is separated by a comma inside it and you want to wrap it in quotes
- Save as UTF-8 in case you are using international characters (otherwise you will get garbled text)
- Resist the urge to embed JSON objects in cells - that way lies madness
If You're Making JSON
- Choose a style for name and stick with it: either snake_case, or camelCase however, not both.
- Make sure you verify the JSON before sending the JSON to anybody (jsonlint.com is your most trusted friend)
- Format it nicely when humans need to read it
- Minify it when sending over the wire
Quick Decision Guide
Contact list with names and emails: CSV. It's a table.
Product catalog where each product has multiple sizes and colors: JSON. You need that nesting.
Survey responses where everyone answers the same questions: CSV. It's literally a spreadsheet.
API response that includes user data with order history: JSON. Complex relationships need hierarchies.
Related Resources
- CSV to Excel Guide - Getting your CSV data into a proper spreadsheet
- Data Converters - CSV, JSON, Excel - convert between them
- Document Converter - Other document format conversions
- All Articles - More file format guides
The Short Version
CSV is for tables. JSON is for everything else. If your data fits naturally in rows and columns with consistent headers, CSV keeps things simple. If you have nested objects, variable structures, or you're talking to an API, JSON is the way to go. And if you've picked wrong, just convert it - that's what we're here for.