100% on-device
Compress an Excel workbook
If a spreadsheet is too big to send, it is usually the images embedded in it. This shrinks those and does not touch a single cell.
How it works
- Drop your .xlsx. It is unpacked in this tab — a .xlsx is a ZIP of XML plus any embedded images.
- Pick a target. Email (1024px) · Balanced (1600px) · Sharp (2200px) — the ceiling for every embedded image.
- Download. Images re-encoded, workbook re-zipped, formulas untouched.
Where the bytes sit in an .xlsx
Inside the ZIP are one XML file per worksheet, a styles part, and xl/sharedStrings.xml - a single table of every distinct piece of text in the workbook, which is why a sheet of unique labels weighs far more than a sheet of numbers. Images, when there are any at all, sit apart from that in xl/media.
Charts are not images. Excel stores a chart as XML pointing at cell ranges and redraws it from your data, so it stays sharp at any zoom and contributes almost nothing. The pictures that do turn up are logos in headers, a screenshot pasted onto a sheet, or a background image, and those are the only parts a picture pass can act on.
Workbook bloat is usually structural, and no image tool reaches it
The commonest cause is the used range. Excel remembers the rectangle out to the furthest cell ever touched, so selecting a whole column and applying a fill or a border creates styled cells all the way down to row 1,048,576 that must be written out. A scroll bar shrunk to a sliver is the symptom; deleting the entire rows and columns beyond your data, then saving and reopening, is the fix.
Pivot tables are the other classic, since a pivot cache keeps its own copy of the source data inside the file. After that come conditional formatting rules fragmented by copy-paste into thousands of near-identical ranges, and defined names left behind by deleted sheets. All of it lives in the sheet XML, which this tool never opens.
Questions
Is my spreadsheet really not uploaded?
Yes — and not as a policy, as a fact of how it is built. There is no upload endpoint: the file is read straight into this browser tab and compressed by code running on your own machine. You can watch the Network tab while it works, or pull your Wi-Fi out mid-compression and it will still finish. Nothing is stored, nothing is queued, and there is no account.
Will my formulas or charts change?
No. The tool never reads your sheet XML — it reaches only into the media folder inside the .xlsx and recompresses the images there. Cells, formulas, named ranges, pivot tables, charts and conditional formatting come out byte-for-byte identical, because they are never opened.
It says there is nothing to shrink.
Then your workbook has no embedded images, and this is the wrong tool for it — honestly said rather than faked. A pure-data .xlsx is already compressed inside its ZIP. If such a file is enormous, the weight is the data itself: look for pivot caches, whole-column formatting, or hundreds of thousands of formula cells. Nothing this tool does can help with that.
What kinds of images does it find?
Anything embedded as a picture — a pasted screenshot, a logo in a header, a photo on a sheet. Charts are not images: Excel draws them from your data, so they are left alone and stay sharp.
What about old .xls files?
The pre-2007 .xls format is not a ZIP and cannot be read this way. Open it in Excel, "Save As" .xlsx, then compress.
Other formats
The same workbench handles all of them — pick a tab above, or start from its own page: