CSV viewer: see a CSV file as a clean table

What a CSV file is

CSV means comma-separated values: plain text where each line is a row and commas split the columns. A value that contains a comma is wrapped in double quotes. The closest thing to a rule book is RFC 4180, and the Library of Congress keeps a format description. In practice CSV files vary: many programs in Europe use semicolons because the comma is the decimal mark there, and database exports often use tabs.

Why open a CSV here instead of in Excel

Excel guesses what each value is, and the guesses change the data: ZIP codes and phone numbers lose their leading zeros, long ID numbers turn into 1.23E+15, and anything that looks like a date becomes one. This viewer shows every value exactly as it is written in the file, which makes it the quickest way to check an export before importing it somewhere. Parsing is done by the open-source Papa Parse library.

Limits

Files up to 200 MB open, and the first 2,000 rows are shown. A multi-gigabyte CSV is too big for any browser tab: on a Mac or Linux, the command head -n 1000 big.csv gives you the first thousand lines, and database tools such as SQLite can import the whole file. The viewer reads UTF-8 text; a file saved in an older encoding can show odd characters in names with accents.

The disadvantages of CSV

• No data types: a number, a date and a word all look the same, so each program guesses.
• One table only: no sheets, no formatting, no formulas.
• No single standard: separators, quoting and encodings differ between programs.

Those are also its strengths: almost every program can read and write it, and it stays readable for decades.