CSV to JSON
Drop your CSV below and it becomes JSON immediately. The conversion happens inside this browser tab, so the file is never uploaded to a server.
How to convert CSV to JSON
- Choose your CSV file, or drag it onto the box below.
- Pick the JSON shape: one object per row, or a header row followed by value rows.
- Download the converted file.
Object shape vs array shape
Object shape produces [{"name":"Ada","age":36}] — readable, self-describing, and what most APIs want. Array shape produces [["name","age"],["Ada",36]] — smaller, and easier to stream row by row.
How types are decided
Types are inferred per column rather than per cell, so a single column never ends up as a mix of numbers and strings. A column is numeric only when every value in it survives conversion unchanged; otherwise the entire column is kept as text.
Questions
Is my file uploaded anywhere?
No. The conversion runs in JavaScript inside your own browser tab. The file is never sent to a server, so nothing is stored, logged or transmitted.
Why is a number in my file still quoted as text in the JSON?
A column becomes numeric only when every value in it converts exactly. If one value would change — 01234 losing its leading zero, or 1250.50 becoming 1250.5 — the whole column stays as text so the data is never silently altered.
What happens to rows with missing values?
Short rows are padded so every row has the same keys. Missing cells become null rather than being dropped.
Does it handle commas and line breaks inside quoted fields?
Yes. Quoted fields containing commas, quotes or line breaks are parsed correctly rather than being split.
How large a file can it handle?
It is limited by your own machine rather than an upload cap. Conversion runs in a background worker so the page stays responsive on large files.
Background
For why CSV files lose leading zeros, arrive as one long column, or show strange characters, see what a CSV file is. This page is one of the free CSV converter tools — all of them run in your browser and none of them upload your file.