CSV Viewer & Editor

This is a spreadsheet-style viewer and editor for CSV, TSV and TXT files and Excel .xlsx workbooks, built for the files that make other tools stall. The file is read in a background worker and the grid only draws the rows on screen, so a 25 MB export with 200,000 rows and 30 columns scrolls like a short list.

It works out the layout on its own: the separator (comma, semicolon, tab or pipe), the quote character, whether the first row holds column names, and the text encoding — UTF-8 with or without a byte-order mark, UTF-16, or Windows-1252, which older Excel versions write. Names such as René come through intact, and every guess can be changed.

Then you edit as in a spreadsheet: type, paste blocks from Excel or Google Sheets, sort, filter, find and replace, remove duplicates, and undo any step. Unlike the Data Converter, which changes formats in one pass, this is where you fix the rows themselves. Everything happens in your browser tab.

1. Drop a file on the box or press “Choose a file” (.csv, .tsv, .txt or .xlsx). You can also paste copied cells into “Or paste your data”, start a “Blank table”, or “Try an example”.
2. Check the line under the file name: rows, columns, separator and encoding. If something looks wrong, open “Reading settings” and pick the separator, quotes, first row or encoding yourself.
3. Click a cell and type, or use the bar above the grid. Each column’s ▾ button sorts, filters and more; the Rows, Columns and Clean up menus work on the selected cells.
4. Use Find to search or replace, Column stats to check a column, and Undo if a step goes wrong.
5. Press Export, choose CSV, TSV, Excel, JSON or Markdown, adjust the options, and press Download or “Copy as text”.

• Opens CSV, TSV, TXT and Excel .xlsx (pick the sheet) in a background worker, so the page never freezes.
• Only the visible rows and columns are drawn, with a sticky header, row numbers and resizable columns.
• Spreadsheet keys: arrows, Shift to select, Ctrl/⌘ + arrows to jump, Tab, Enter or F2 to edit, Delete to clear, Esc to cancel.
• Copy and paste blocks with Excel, Google Sheets and Numbers; pasting past the edge adds rows and columns.
• Add, delete, move and rename rows and columns; switch the first row between data and column names.
• Sorting that understands numbers (1,234.50, $9, 45%), dates and text with numbers in it; filters such as contains, is, empty, and greater or less than.
• Find and replace with match case, whole cell, one column only, or regular expressions.
• Column stats: type, filled and empty cells, distinct values, range, average, total and most common values.
• Remove duplicate rows (whole rows or selected columns), trim spaces, remove empty rows, and undo or redo every change.
• Export CSV (separator, quotes, line endings, UTF-8 mark), TSV, JSON, Markdown, or Excel with numbers kept as numbers.

• An untouched UTF-8 file with standard quoting saves back byte for byte: Export starts with its separator, line endings and byte-order mark. Quotes around fields that never needed them are dropped.
• Sorting is stable: to sort by city, then by date within each city, sort by date first, then by city.
• If a European CSV opens in one column, pick Semicolon under Reading settings.