Why are only some fields quoted?

Because RFC 4180 only requires quoting when a field contains the delimiter, a double quote or a line break. Quoting everything is legal but noisy, and some importers carry the extra quotes into the value.

Can I output semicolons instead of commas?

Yes. Pick the delimiter above the editor and the quoting decision follows it: a field containing a semicolon is quoted when semicolon is the delimiter, and left alone when comma is.

Is this the exact inverse of CSV to TSV?

Not quite, and the asymmetry is the point. CSV can express a value containing a tab; TSV cannot express one containing a tab. This direction never loses anything — the other one can.

TSV to CSV — Opens Where TSV Does Not

Convert tab-separated values to CSV, quoting only the fields RFC 4180 requires. The result opens in the many tools that expect a comma.

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Delimiter

Swap: CSV → TSV

TSV input

CSV output

What this tool does

Fields are split on tabs and rewritten with your chosen delimiter, quoted according to RFC 4180. A field is wrapped in quotes only if it contains the delimiter, a double quote, or a line break; an inner quote is doubled rather than backslash-escaped, because CSV has no backslash escape.

Anything else is written as it is. A value with no special character is already a valid CSV field, and quoting it anyway adds noise some importers carry into the imported value.

Why this direction is the safe one

The two conversions are not mirror images. CSV has a way to express every character a field might hold: a tab, a comma, a quote, even a line break, all fit inside a quoted field. TSV has no such mechanism — in its common understanding a value simply cannot contain a tab, because the tab is the delimiter.

So going from TSV to CSV, nothing has to be dropped or reshaped. Going the other way, a value containing a tab has nowhere to live.

That is a useful rule when you are choosing an interchange format rather than converting a file you were handed: if the data might contain tabs or line breaks, CSV is the format that can hold it.

Line breaks inside a field

A TSV field rarely contains one, but if yours does, it survives: the field is quoted and the break kept as part of the value, which is legal CSV. It is up to the consuming parser to read it as part of the field rather than as a new record.

Private by design

Everything runs locally in your browser with JavaScript. Your data is never uploaded, which makes the tool safe for sensitive content, and it keeps working offline.

Frequently asked questions

Why are only some fields quoted?: Because RFC 4180 only requires quoting when a field contains the delimiter, a double quote or a line break. Quoting everything is legal but noisy, and some importers carry the extra quotes into the value.
Can I output semicolons instead of commas?: Yes. Pick the delimiter above the editor and the quoting decision follows it: a field containing a semicolon is quoted when semicolon is the delimiter, and left alone when comma is.
Is this the exact inverse of CSV to TSV?: Not quite, and the asymmetry is the point. CSV can express a value containing a tab; TSV cannot express one containing a tab. This direction never loses anything — the other one can.