Convert JSON to CSV.
Turn JSON data into a spreadsheet-ready CSV file — without a single file ever leaving your device.
Three steps, no waiting on a server
Altto's JSON to CSV tool works right in your browser tab, so there's no upload queue and no “processing your file” spinner tied to someone else's servers.
Add your JSON file
Drop in a .json file — an array of objects works best.
Convert
Altto flattens it into rows and columns, locally.
Save your CSV
Get back a .csv file, ready to open in a spreadsheet.
Why this runs in your browser, not on a server
JSON exports often hold user records or app data — not something you’d want sitting on a stranger’s server just to change the file format. Altto skips that step completely — there’s no server for it to go to.
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Nothing is uploaded, everEvery file is read and converted by code that runs in this browser tab, because there’s no server on the other end. That also means we can’t see it, copy it or keep it.
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No account, no email wallConvert as many files as you like without signing up or handing over an email address.
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No data silently droppedNested values are preserved as JSON text inside their cell rather than discarded.
files stored on our servers. There’s no server involved at all — the CSV is built once, then everything happens locally.
Frequently asked questions
The practical details on what this tool can and can’t do. Need to go the other way? See CSV to JSON.
What kind of JSON works best?
[{"name":"Alice","age":30}] — converts cleanly into rows and columns. A single object is treated as one row.