Prepare a CSV for Excel without broken columns
A CSV is a text convention, not a standard data type. The same file can look perfect in one program and be shifted by one column in another. Most damage is visible in seconds once you know what to look for.
Delimiter first
The first thing to settle is whether fields are separated by commas, semicolons or tabs. Files exported in regions where the comma is a decimal separator often use semicolons, because "1,25" would otherwise look like two fields.
If a file opens with every row crammed into one column, the program did not guess the same delimiter. Re-export with an explicit delimiter, or convert through JSON, rather than fixing each row by hand.
Quotes are part of the data
Any field containing the delimiter, a quote or a line break must be wrapped in double quotes, and a double quote inside it is written twice. That is why an address like "12 High St, Flat 3" stays in one cell while an unquoted version does not.
Quoted fields can also contain line breaks. A row that seems to spill onto a second line may be correct data with an embedded newline, not a broken export.
What this tool does and does not decide
The CSV and JSON tools here convert structure, not meaning. A leading zero in a phone number, a date written 03/04/2026 and a numeric ID longer than 16 digits all need a decision that plain conversion cannot make.
Do not fix those by padding by hand after conversion. Decide the rule before sharing the file: keep identifiers as text, use an unambiguous date format such as 2026-04-03, and keep currency values out of display formatting.
Before you send it
- Open the file in a text editor and check the first and last rows
- Confirm the number of fields is the same in a sample of rows
- Check that empty cells stay empty instead of becoming the text "null"
- Check line endings: different systems disagree about CRLF and LF
- Re-import once into a new sheet, not over the file you are inspecting