CSV delimiter detection explained (comma vs semicolon vs tab)
If your converted output shows “shifted” columns, the delimiter is usually wrong. This guide explains how delimiter detection works and how to quickly verify the right separator.
What is a delimiter?
A delimiter is the character separating columns in a row. The most common is a comma, but many CSV exports use semicolons (regional Excel settings) or tabs (TSV). If the parser chooses the wrong one, every row will be split incorrectly.
How “auto-detection” typically works
- Look at the first few non-empty lines.
- Count occurrences of candidates (comma, semicolon, tab) outside quotes.
- Pick the delimiter with the most consistent splits.
Detection is a heuristic. It works well for typical exports, but edge cases (lots of commas inside quotes, single-column files, mixed separators) can confuse it.
Quick checks to confirm the delimiter
- Header row: does it split into the expected number of columns?
- Visual clue: semicolon CSV often comes from Excel in Europe.
- TSV clue: the file looks “aligned” when pasted into a text editor with tabs.
What to do when columns shift
- Check if the file uses semicolons or tabs.
- Verify quoting: commas inside quoted values must not be treated as delimiters.
- Confirm that every row has the same column count as the header.
Trust note: All processing happens locally in your browser. Files are never uploaded.
Practical checklist (fast)
If you’re stuck, use this quick checklist to narrow the problem before you try “random fixes”. Start by validating the input format (syntax first), then confirm shape expectations (array vs object, headers vs rows). Convert a small sample, inspect the output, and only then export the full result.
- Validate: confirm the input is strict JSON/XML/CSV (no stray characters).
- Confirm shape: arrays vs objects; headers vs row lengths; repeated tags vs arrays.
- Test a sample: first 20–50 rows/items are enough to detect parsing issues.
- Export: copy/download the output and re-check it in the consumer (script/spreadsheet/API).
This workflow is privacy-first by design: All processing happens locally in your browser. Files are never uploaded.
FAQ
Why do some rows have a different number of columns? It’s often broken quoting or embedded delimiters/newlines in values.
Is TSV just CSV with tabs? Practically yes: tab-separated values are parsed the same way, just with a tab delimiter.