How do I convert CSV to JSON?

Add your CSV file to the upload area above, then press Convert. The JSON file downloads straight to your device. You do not need an account, and there is no watermark.

Are my files uploaded to a server?

No. This conversion runs entirely inside your browser using WebAssembly, so the file never leaves your device — you can even disconnect from the internet after the page loads and it will still work.

Does converting to JSON reduce quality?

No. JSON is a lossless format, so the conversion preserves exactly what is in your CSV file. Note that it cannot recover detail that was already discarded when the CSV was first created — a lossless container does not undo earlier compression.

How large a file can I convert?

Up to 100 MB per file for this conversion. Because the work happens in your browser, the practical limit is your device's memory — larger files work on a desktop with plenty of RAM and may fail on an older phone.

Can I convert several files at once?

Yes. Add as many as you like and press Convert All. Each file is processed independently, so one failure does not stop the rest, and you can download everything together as a ZIP.

Can I use this on my phone?

Yes. FileTools360 works in mobile browsers on iOS and Android, including choosing files straight from your camera roll. Very large videos may run out of memory on a phone — those are better converted on a laptop.

SpreadsheetLosslessRuns in your browser

CSV to JSON Converter

Turn CSV files into JSON in a couple of clicks. Flat tabular text — one table, no formatting. The default data interchange format for APIs. The conversion is lossless — every pixel, sample or byte in the source is preserved.

On your deviceNever uploadedGone when you close the tabHow this works

Drop your files here

CSV files (.csv) · up to 100 MB each

or paste files from your clipboard

Ready when you are

Drop a CSV file above and FileTools360 will turn it into JSON — right here on your device, without uploading anything.

⌘K to search converters

How to use it

1
Add your CSV files
Drag them onto the upload area, choose them from your device, or paste them from your clipboard. You can queue several at once.
2
Adjust the settings if you want to
The defaults suit most people. Open Advanced to control delimiter and header handling and indentation and element names.
3
Convert and download
Press Convert. Everything happens on your own device — nothing is uploaded. Download files one by one, or grab them all as a ZIP.

CSV and JSON explained

CSV is plain text where each line is a row and commas separate the fields. There is no formatting, no formulas, and no second sheet — which is precisely why every system on earth can read it.

JSON represents structured data as nested objects and arrays. It came from JavaScript but is now the default interchange format for essentially every web API.

Where CSV files come from: Database exports, analytics tools and data interchange between systems.
Where JSON is used: APIs, configuration files and application data exports.

CSV vs JSON

The two formats solve different problems, which is why converting between them involves trade-offs rather than a straight upgrade.

CSV compared with JSON
Property	Source	Target
Compression	None	None
Introduced	—	2001
Browser support	Every spreadsheet, database and programming language.	Every modern language and tool.

CSV is stronger at: Readable by every spreadsheet, database and programming language. Plain text, so it diffs and streams well. Tiny files.
JSON is stronger at: Native support in every modern language. Handles arbitrary nesting. Distinguishes strings, numbers, booleans and null.

Why convert CSV to JSON?

People make this switch when they run into the limits of CSV: the data needs formulas, formatting or multiple sheets. JSON is the better fit when APIs, configuration and any data with structure beyond a flat table.

CSV limitations that prompt the switch: Exactly one table — no sheets, formatting or formulas. No type information, so leading zeros and long numbers get mangled. The 'comma' is not guaranteed; European exports often use semicolons.
What you give up: No comments allowed. Verbose for large tabular datasets.

What is preserved when converting CSV to JSON?

Both formats store the content without discarding data, so this conversion preserves it exactly. The file size may change because the two formats compress differently, but the content itself is unaffected.

CSV has no notion of data types. A product code like 007 becomes 7 unless the importing tool is told otherwise — which is a property of CSV, not a bug in the converter.

About these formats

Source

Comma-Separated Values

Flat tabular text — one table, no formatting.

Extensions: .csv
MIME type: text/csv
Best for: Data imports and exports · Databases · Scripts
Compatibility: Every spreadsheet, database and programming language.

Target

JavaScript Object Notation

The default data interchange format for APIs.

Extensions: .json
MIME type: application/json
Best for: APIs · Configuration · Structured records
Compatibility: Every modern language and tool.

Good to know