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.csv

CSV test files

Comma-separated files with the rows, delimiter and edge cases you pick: from a tidy 10-row sample to a million rows full of quotes, line breaks and Unicode.

Open the .csv generator

Or start from a preset

What is a CSV file?

Short answer

A CSV file is plain text where each line is a record and fields are separated by a delimiter, usually a comma. RFC 4180 describes the common rules: quote a field that holds the delimiter, a quote or a line break, and double any quote inside it.

CSV looks simple, which is why importers break on it. Excel on Windows needs a byte order mark to read UTF-8 accents, some parsers choke on a line break inside a quoted cell, and a cell that starts with = can run as a formula when the file is opened in a spreadsheet.

Anatomy of a CSV file

  • header rowOptional first line with the column names
  • delimiterComma, semicolon (common in Europe), tab or pipe
  • "quoted field"Needed when a value holds the delimiter, a quote or a line break
  • ""A quote inside a quoted field is written twice
  • CRLFRFC 4180 line ending; many tools also accept LF
  • BOMOptional EF BB BF bytes that tell Excel the file is UTF-8

What you can generate

  • Quotes, embedded delimiters and line breaks inside cells
  • Empty cells, leading zeros (00501) and spaces around values
  • Unicode names, cities and emoji, with or without a UTF-8 BOM
  • Formula-like cells (=1+1, +SUM, @) for CSV injection tests
  • Ragged rows with a missing or extra field
  • Every field quoted, or quoting switched off to make a broken file
  • Up to 1,000,000 rows and 40 columns, written in a background worker

How to make one

  1. Open the CSV generator, or start from a preset above.
  2. Set the size and switch on the edge cases you need; the preview and size estimate follow every change.
  3. Generate, then download. The file is made in your browser, and the same preset and seed always give you the same file.

Questions

Yes, unless you ask for a broken one. Fields that need it are quoted, inner quotes are doubled, and lines end in CRLF by default. Choose ragged rows or switch quoting off when you want a file that should fail.

Excel on Windows reads a CSV without a BOM in the local code page, so ö becomes ö. With the BOM switched on, Excel reads the file as UTF-8.

Yes. The generator is seeded: the same settings and seed give the same bytes, and the preset link carries both.

They test CSV injection handling. Cells starting with =, +, - or @ can run as formulas when opened in a spreadsheet, so exporters often escape them.

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