Free CSV to JSON Converter with No Sign-up and No Upload
This free CSV to JSON converter turns a table of comma-separated rows into JSON records. There is no sign-up or login, no watermark, and nothing to upload: the data is converted in your browser and never leaves your device.
Developers use it to feed a CSV export into an API, a front end or a test fixture. It works best with a list of records that share the same fields, where the header row names each value.
- Free
- No sign-up
- Never uploaded
- No watermark
Your files are converted on your device and never uploaded.
How to convert
- Drag your CSV files onto the page or choose them with the file picker.
- Pick JSON as the target format.
- Check the options, then start the conversion.
- Download each JSON file, or take a batch as one ZIP.
Features
- Runs natively in your browser with no engine download.
- Works best with records that share the same fields.
- Handy for APIs, fixtures and scripts.
- Batch conversion of several files.
- No watermark and no account.
Supported formats
About the formats
CSV and JSON compared
CSV is flat: rows and columns of text with no nesting. JSON is the usual format for web APIs and can hold objects, lists, numbers and nested values. A table maps neatly to a list of records, one per row, using the header names as keys.
Because CSV carries no type information, check how numbers and empty cells are written in the result before using it.
Privacy: how it works
- Your CSV files stay on your device. The page reads each file with the browser's file API, converts it with code running in the tab, and hands the result back as a download. No upload happens, so there is no copy of your file on our servers to protect, delete or leak.
- There is nothing to sign up for and no login. The converter does not ask for an email address, and it does not need to know who you are to do its job.
- You can check the claim yourself: open your browser developer tools, watch the Network tab while a file converts, and you will see no request that carries your file.
- Data exports can hold emails and internal IDs. Converting locally means none of it passes through a third-party server.
Tips
- Give every column a unique header name, since the headers become the keys.
- Avoid blank header cells, which leave values without a clear key.
- Look at numbers and empty cells in the output to confirm they match what your code expects.
- If the file has no header row, add one first.
- Use JSON Lines instead when the file is very large and you want to read it one record at a time.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial, no credit card and no watermark added to your results. Ulkaa Tool does the conversion with your own device, so there is no server bill to pass on to you.
Are my files uploaded?
No. Your CSV files are read and converted inside your browser and are never sent to Ulkaa or to anyone else. The result is created on your device and you save it from there.
Do I need an account?
No. There is no sign-up and no login. Open the page, add your files and convert. An Ulkaa account is not needed for anything on this tool.
Is there a file size limit?
No limit is set by us. The real limit is your device: the conversion uses your own memory and processor, so very large files can be slow, and a very big batch may need to be split into smaller runs.