CSV Viewer: Open and Inspect Large CSV Files

Pick a .csv, .tsv or .txt file and the viewer parses it with Papa Parse. It tries comma, semicolon, tab and pipe, picks the delimiter that fits best, and lets you override the choice when the guess is wrong. Spreadsheet exports from Excel in many European locales use semicolons, while database dumps often use tabs or pipes, so the override matters. Choose the encoding as well: UTF-8, Windows-1252, ISO-8859-1 or UTF-16. If accented letters appear as odd symbols, switch from UTF-8 to Windows-1252 and the text usually becomes right.

Toggle whether the first row is a header, click a column header to sort, and type in the filter box to keep only rows containing your text. The viewer shows how many rows match. The grid is virtualised, so only visible rows are drawn, and the file is read in chunks so the page stays responsive while it loads.

Quoted fields, doubled quotes, newlines inside a quoted cell and a byte order mark at the start of the file are all handled. A cell such as "Sara; Jr." stays one cell even when the delimiter is a semicolon. The viewer also reports rows whose number of fields differs from the header, which is the quickest way to find a stray delimiter, an unescaped quote or a truncated line in an export before it breaks an import.

All values are shown as text. There is no type inference, so 00123 keeps its zeros and 1e5 is not turned into a number. That is deliberate for inspection, but remember it when you reuse the data: your importer decides whether a column is a number, a date or a string. Export the filtered and sorted rows as CSV or JSON to hand a clean subset to a script, a Mongo import or a test fixture.

Files up to 100 MB are accepted, with a warning above 25 MB because everything is held in memory. Sorting is available up to 300,000 rows; beyond that you can still scroll, filter and export, but sorting is switched off so the page does not stall. Very large files can be slow on phones and low-memory laptops, in which case split the file or filter it with a command-line tool first.

The viewer does not edit anything. It is a read-only inspector, so the original file is never changed. For an Excel file use the XLSX viewer instead, since csv has no sheets, formulas or formatting. When a CSV from a spreadsheet looks wrong, check the delimiter, the encoding and the row-length report first, in that order.