Why not just find-and-replace tabs with commas?

Because a value containing a comma then splits into two columns. Converting properly means quoting the values that need it, which is exactly what this page does.

Will my values be changed?

Nothing is retyped. Every value is carried through as text: 00412 keeps its zeros, 1.10 keeps its trailing zero, and a sixteen-digit number never becomes 1.23E+15.

My file is .txt — will it read?

Yes. Plenty of systems export tab-separated data with a .txt name; the page reads the tabs, not the file name.

What about semicolon-separated files?

That is the European CSV problem, and it comes with decimal commas that need care — the delimiter fixer handles both.

Is my file uploaded anywhere?

No. The conversion runs inside this page: when you convert TSV to CSV here, the browser is told to block outbound connections, so nothing can be sent to another server. Keep the Network tab of your developer tools open while you convert TSV to CSV: every request in it goes to this site, and none carries your file.

Convert TSV to CSV — with the quoting done right

Turn a tab-separated file into a comma-separated one, quoting the values that need it. Runs entirely in your browser; nothing is uploaded or retyped.

TSV to CSVRunning on your device

Source

Your TSV

or drag one here · it stays on your device

Result

Add a tab-separated file. The download is the same table, comma-separated and quoted correctly.

How this works

Add your TSV. Drop the file onto the page.
Check the preview. The grid shows the table as it was read.
Download. Save the CSV.

What it cannot do

Semicolon-separated European files are a different fix, with decimal commas to keep whole — the delimiter fixer is the page for those.
The output uses minimal quoting: only values that contain a comma, a quote or a line break gain quotes.
Files that are not UTF-8 are refused with the way out stated, rather than converted into mojibake.

Questions

Why not just find-and-replace tabs with commas?: Because a value containing a comma then splits into two columns. Converting properly means quoting the values that need it, which is exactly what this page does.
Will my values be changed?: Nothing is retyped. Every value is carried through as text: 00412 keeps its zeros, 1.10 keeps its trailing zero, and a sixteen-digit number never becomes 1.23E+15.
My file is .txt — will it read?: Yes. Plenty of systems export tab-separated data with a .txt name; the page reads the tabs, not the file name.
What about semicolon-separated files?: That is the European CSV problem, and it comes with decimal commas that need care — the delimiter fixer handles both.
Is my file uploaded anywhere?: No. The conversion runs inside this page: when you convert TSV to CSV here, the browser is told to block outbound connections, so nothing can be sent to another server. Keep the Network tab of your developer tools open while you convert TSV to CSV: every request in it goes to this site, and none carries your file.

Your file is processed in this page and never uploaded — the privacy page shows how to confirm that yourself.