CSV line ending converter: switch a CSV between Windows, Mac and Unix line endings
In short: Upload or paste a list, pick Windows, Unix or old Mac line endings, choose whether to add a byte order mark, and download the rewritten file. Limit: It rewrites a CSV from its parsed cells, so the original quoting style is not kept.
Upload a CSV or .xlsx file, or paste it with a header row. Pick the line ending you need: CRLF for Windows and Excel, LF for Unix, Linux and most import tools, or CR for very old Mac files. Choose whether to add a UTF-8 byte order mark, then download the file with every row ended the same way.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. Check your list free nowSee pricing
Sample result
Three example rows written with LF endings and a byte order mark come to 120 bytes; 1 row had a line break in a cell.
- Rows written
- 3
- File size
- 120 bytes
- Byte order mark
- Added
What this means for you
A line ending does not show which addresses exist; a check does.
- CRLF, LF or CR
- Byte order mark option
- Quote every value
- Exact size shown
- Line ending
- CSV
- BOM
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
File ready? Check the addresses before you import it.
- Download the file, or use the check button under the result, which carries its addresses across.
- Upload or paste it at /verify. Every address gets a live mailbox check, and the first 100 email checks are free with a Google sign-in, no card.
How do I change the line endings of a CSV file?
- Upload the file as a CSV or .xlsx, or paste the cells with the header row first.
- Pick the line ending: Windows (CRLF), Unix and modern Mac (LF) or old Mac (CR).
- Tick the byte order mark if the file will be opened in Excel, and tick quote every value if your importer needs it.
- Check the file size and download the rewritten CSV.
Example
- You enter
- A header and two rows (Ava Stone and José Pérez), one with a two-line note in quotes, written with Unix line endings (LF) and a byte order mark.
- You get
- 3 rows written, 120 bytes, every row ended with LF and the byte order mark first. 1 row had a line break in a cell, now ending the same way.
- Limits
- Runs in your browser; nothing is uploaded. It rewrites the file from its cells, so it cannot fix text saved in the wrong encoding.
Why do line endings break a CSV import?
Windows ends a line with two characters, carriage return and line feed (CRLF). Unix, Linux and current macOS use one, line feed (LF). Very old Mac files used a lone carriage return (CR). Some importers read a whole CR file as one long row, and some scripts keep a stray carriage return on the end of the last column.
Rewriting every row with one ending removes that mismatch. Pick the one the tool you are importing into expects; when its help page does not say, LF is the safest choice for web tools and CRLF for Excel.
What is the byte order mark for?
A byte order mark is three bytes at the very start of a UTF-8 file. Excel uses it to know the file is UTF-8, so names such as José or Zoë show correctly instead of as odd symbols. Many web importers and scripts do not expect it and read it as part of the first column name, so leave it off for those.
If accents already look wrong, the file may have been saved in a different encoding; try the CSV encoding fixer first.
What happens to line breaks inside a cell?
A quoted cell can hold a line break, such as a multi-line note. The tool writes those breaks with the same ending as the rows and tells you how many rows had one. To remove them instead, use the whitespace and hidden character cleaner.
Who uses this tool, and for what?
- Cold emailers
- Fix a lead file that a sending tool reads as a single row after an export from an old system.
- Marketers
- Add a byte order mark so a list with accented names opens correctly in Excel.
- Developers
- Normalise CSV fixtures to LF before committing them or running a script on them.
What can’t this tool tell you?
- It rewrites a CSV from its parsed cells, so the original quoting style is not kept.
- It cannot repair a file saved in the wrong text encoding.
- Only the first sheet of a workbook is read.
- A byte order mark helps Excel but can confuse tools that do not expect it.
Common questions
- Which line ending should I pick?
- CRLF for Excel and Windows tools, LF for most web importers, Linux and scripts. The importing tool's help page usually says which it wants.
- Does it change my data?
- No. Only the row endings, the optional quotes and the optional byte order mark change. The cells keep their text.
- What does quote every value do?
- It wraps each cell in quotes, which some importers need to read numbers such as ZIP codes as text. Quotes inside a value are doubled.
- Can it read an old Mac CR file?
- Yes. Paste the text or upload the file and it is read whatever its endings were, then written with the one you choose.
- Why is the file size shown?
- To check against an importer's size limit. It is the exact number of bytes of the file you will download.
- Is my file uploaded?
- No. It is read in your browser and goes nowhere.
A tidy list can still be full of dead addresses.
Extracting, deduplicating and syntax checks all work on the text of an address. None of them can tell whether the mailbox exists. Only the server that hosts it can answer that, through an SMTP check, and that is what the paid product does.
- Upload the cleaned file as it is: CSVs up to 100,000 rows
- A real SMTP mailbox check on every row, with catch-all detection
- Small list? Starter at $9/mo covers 2,500 emails a month, cancel anytime
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.