Convert CSV to JSON

Convert CSV to JSON in your browser: load your CSV, choose JSON as the target, and download the result. This conversion preserves every value in your data, and nothing is uploaded to a server.

Convert CSV to JSONRuns in your browser. Nothing uploaded.

When you need this

An export arrives as CSV and the API you are feeding wants JSON. This is the most common conversion in the set and the one most often got wrong by hand, because the interesting decisions — types, empty cells, duplicate headers — are all invisible until something downstream breaks.

How to convert CSV to JSON

Load your CSV

Drag the .csv file in, or paste the rows. An export from Excel, Numbers or a database client works unchanged, including a quoted header row. Nothing leaves your browser at this or any later step.

Choose the target format

Press Ctrl+Shift+K (Cmd+Shift+K on a Mac) to open the conversion panel, then pick JSON as the target. The source and the result sit side by side.

Read the loss report

The panel shows whether the conversion is lossless for your particular data, and lists every value it had to transform. Adjust indentation, key sorting and null handling if you need to.

Take the JSON

Download the .json file, copy it, or open it as a new tab to keep working on it in the JSON views.

What survives the conversion

CSV to JSON is lossless for your data: convert back and every value returns. Formatting does not survive — comments and whitespace are lost by every conversion in every direction, in every tool.

• Numbers and booleans become JSON types rather than strings, which is what almost everyone wants — but it means an identifier like 007 becomes 7. If a column is an identifier rather than a quantity, check it.
• The header row becomes the object keys. A file with no header produces keys from the first row of data, which is worth noticing before you send it anywhere.
• An empty cell becomes an empty string, not null. The file does not distinguish "blank" from "absent", so inventing a null would be inventing information.

A worked example

Type inference, including the case that catches people out:

id,code,active
1,007,true

[
  {
    "id": 1,
    "code": 7,
    "active": true
  }
]

Privacy

The conversion runs in your browser — in a Web Worker for anything above a quarter of a megabyte, so the page stays responsive. Your data is not uploaded, not logged and not stored. There is no account, and the whole thing works offline.

Convert CSV to JSON