CSV, TSV, and why the delimiter matters
A CSV and a TSV are the same idea — a plain-text table, one record per line — separated by different characters. CSV uses a comma between fields; TSV uses a tab. The choice matters because whichever character is the separator can’t appear freely inside your data. Commas turn up constantly in addresses, product names and European decimal numbers, so CSV leans on quoting ("Smith, Jr.") to keep them straight. Tabs almost never appear inside real values, so TSV usually needs no quoting at all — which is exactly why data teams and bioinformatics tools often prefer it.
When to pick TSV vs CSV
Short version: use whatever the system on the other end expects. If an importer keeps splitting your fields on the commas inside them, switching to tab-separated often fixes it instantly.
| Situation | Better choice |
|---|---|
| Uploading to most marketplaces, CRMs, ad platforms | CSV (comma) |
| Data has lots of commas and the importer keeps mis-splitting it | TSV (tab) |
| European locale where comma is the decimal separator | Semicolon or TSV |
| Bioinformatics / data-science pipelines (BED, GFF, many ML tools) | TSV (tab) |
| A tool that specifically asks for pipe-delimited | Pipe ( | ) |
How this converter works — and why it’s safe
The converter reads your file with the same tested parser that powers the rest of CSVUndo: it auto-detects the input delimiter, respects quoted fields (including quoted commas and line breaks), then re-writes every row using the delimiter you pick. If a value contains the new delimiter, it is quoted automatically so nothing shifts. Your actual values are never altered — a barcode stays a barcode, a leading zero stays a leading zero.
One thing worth knowing: if you convert to TSV and then reopen it in Excel by double-clicking, Excel can still mangle long numbers and drop leading zeros, because that’s Excel’s type-guessing, not the file’s fault. Tick Excel-safe before converting and identifier codes are wrapped as ="00501" so Excel leaves them alone. If your file has already been damaged, run it through the matching repair tool first:
If the numbers are in 1.23E+12 notation, the ZIP codes lost their zeros, or the text is full of é, fix that first — then convert the clean file to whatever delimiter you need.
Learn more
For the full background on the two formats — escaping rules, performance, and which tools expect which — see our guide on converting TSV to CSV (and back). If your file opened with every field crammed into one column, that’s a delimiter mismatch rather than a conversion job — our guide on a CSV that opens in one column walks through it, and you can browse all guides for every other Excel-and-CSV mishap.
Frequently asked questions
What is the difference between CSV and TSV?
Both are plain-text tables with one row per line. CSV separates fields with commas; TSV separates them with tab characters. Because tabs almost never appear inside real data, TSV rarely needs the quoting that CSV uses to protect commas. Otherwise they hold the same data.
How do I convert a CSV to TSV (or a TSV back to CSV)?
Drop the file into the converter above, choose Tab as the output delimiter (or Comma to go the other way), and click Convert & Download. It runs in your browser, so nothing is uploaded, the input delimiter is detected automatically, and quoted fields are handled correctly.
Will converting the delimiter break my leading zeros or barcodes?
No. Converting changes only the character between fields; the values themselves pass through unchanged. If you’ll reopen the result in Excel, tick Excel-safe so codes like 00501 and long barcodes are wrapped as ="…" and Excel can’t re-strip the zeros or collapse them into scientific notation.
Is my file uploaded anywhere?
No. The converter is JavaScript running in your own browser tab. The file never leaves your device, and the tool keeps working even if you disconnect from the internet after the page loads.