Old .xls files without Excel
Plenty of organizations still have more .xls files than .xlsx ones — they are produced by systems that have not been updated since the 2000s. You can open such a file without Excel, and without asking the sender to "re-save it in the new format".
Free for personal use. No Excel needed — the file is parsed in your browser. Windows version — 3.5 MB, no installation: details. Organizations: license.
How .xls differs from .xlsx
.xlsx is a ZIP with XML inside, so almost any tool can read it. .xls is a binary BIFF format inside an OLE2 container: a stream of records of the form "type, length, data". You cannot read it by eye — you need a parser that knows all its traps, such as a shared string table that gets split in the middle of a string.
Two generations of the format
| Version | What is inside | Worth knowing |
|---|---|---|
| Excel 97–2003 (BIFF8) | Unicode text | opens as is |
| Excel 5.0/95 (BIFF5/7) | text in a code page | if you see garbage instead of letters, change the encoding in the file parsing panel to the one the file was made with (for example windows-1252 for Western European files) |
What you can and cannot see
- values, dates (by the cell format, with the 1904 system taken into account), booleans and formula errors;
- all sheets — pick one in the file parsing panel; hidden sheets are marked;
- merged cells — the value is repeated across the area, as in Excel;
- formulas — only the calculated result: .xls stores a formula as a parsed token tree, not as text;
- a password-protected workbook does not open — you get a clear message instead.
Converting .xls to .xlsx or CSV
Open the file and choose Export: Excel .xlsx, CSV, DBF, JSON or SQL. Dates stay dates, and text codes with leading zeros stay text. Saving edits back to .xls is not possible, because there is no writer for the binary format — export to .xlsx and edit that.
FAQ
What is the largest .xls that will open?
The workbook is parsed into memory as a whole, with a limit of 256 MB. For .xls that is a lot: the Excel 97–2003 format itself allows no more than 65,536 rows per sheet.
Will an .xls that is really HTML open?
Some programs save an HTML table with the .xls extension. That is not an Excel format; open such a file in a browser or rename it to .html.
Is the file uploaded to a server?
No, parsing happens in the browser.
Free for personal use. Your file is not uploaded to a server. Windows version — 3.5 MB, no installation: details. Organizations: license.