Sheetsmith
Why CSV files look wrong in a spreadsheet
CSV is only a convention, and spreadsheets guess at it. The three usual failures: the delimiter isn't a comma (much of continental Europe exports with semicolons, because the comma is the decimal separator there; database exports often use tabs or pipes); quoted fields containing commas or line breaks get split into extra columns by naive parsers; and leading zeros in codes and phone numbers get stripped because the spreadsheet decides they are numbers. This viewer detects the delimiter from the first lines, follows the quoting rules of RFC 4180 (a quote inside a quoted field is written as two quotes), and never converts values — everything is shown as text, exactly as it is in the file.
UTF-8 and the "é" problem
If names come out as José the file is UTF-8 but was read as Windows-1252, or the other way round. Files are read here as UTF-8, which is what almost everything exports today; a byte-order mark at the start is stripped so the first header isn't polluted. If your file was saved from an old Excel as "CSV" rather than "CSV UTF-8", accented characters may still be wrong — re-export with the UTF-8 option.
Sorting and searching
Click a column header to sort; click again to reverse. Sorting is numeric when every value in the column looks like a number, otherwise alphabetical, so a column of prices sorts by value and a column of product codes sorts as text. Search filters rows to those containing the text in any column; the row count updates to show matches out of the total.
Export as JSON
The JSON export produces an array of objects keyed by the header row — the shape most APIs and scripts expect. Values stay as strings; convert them where you consume them, since only your code knows which columns are really numbers.
Questions
How big a file can it open?
A few hundred thousand rows parse fine; rendering is capped at the first 5,000 rows for speed, with the full count shown. Search and sort operate on all rows.
Does it handle line breaks inside a quoted cell?
Yes — a quoted field may span lines, per RFC 4180, and is shown in one cell.
Is my file uploaded anywhere?
No. The file is read by your browser and never sent to a server; there is no server. Close the tab and it's gone.