Compress many PDFs at once, a whole folder in 1 run

Steps

1. Add the files. Drag a folder onto the page, or press or a whole folder under the drop zone and choose it. Subfolders are included, hidden files are not. You can also select many PDFs in the file picker, or drop more files later; they are added to the list.
2. Check the list. Each file shows its page count and size. Anything that is not a PDF is left out, and a line says how many. Remove a file with its Remove button.
3. Pick 1 setting for all of them. A preset: Email (pictures at 110 dpi) for files read on a screen, Web (150 dpi) when people zoom in, Print (300 dpi) for paper. Or a Size target, which each file has to meet on its own: a 1 MB target means every file under 1 MB, not the batch. Each file gets the best quality that fits under it, and a file already under the target comes back untouched.
4. Press Compress. The progress line shows which file of how many is running, and what it is doing to it.
5. Read the result. Every finished file is listed with its new size and its own Download button. Below the list, the report gives each file its before-and-after line, then what was done and any warnings, such as a file that could not get smaller.
6. Save them. Download all as zip gives you 1 zip with every file. In Chrome and Edge, Save to a folder writes them straight into a folder you pick, 1 by 1, with no zip.

A note on Chrome and Edge: when you choose a folder with the button, the browser asks whether to “upload” its files to the site. That is the browser’s standard wording for any web page that reads a folder. Nothing is uploaded: the files are read in your tab. You can check: compress 1 file with the connection on (that fetches the engine, which your browser then keeps), turn Wi-Fi off, and run the folder. Dragging the folder onto the page skips the question.

What a mixed folder gives back

Real folders mix scans, photos and typed documents, and they do not shrink alike. Here is what our test files give with the Email preset, measured on 11 October 2026:

Read the results with that in mind. A typed document that comes back the same size is not a failure; there was nothing to take out, and the tool hands back the original rather than a pointless copy. The scans and photos are where the folder’s weight was.

Files are done 1 at a time

The compressor works through the list in order, 1 file at a time, in a background worker in your tab. The heavy work never holds more than 1 file, so what a run needs in memory is set by the biggest file in it, not by how many files there are. The finished, smaller files wait in the tab until you save them.

That has 2 consequences:

• One bad file does not stop the run. A damaged file or one with a password is skipped, listed as not done, with the reason, and the next file starts.
• Time adds up. Our 10-page scan takes about 3 seconds with the Email preset on a mid-range laptop; a folder of 50 such files takes a few minutes. A size target can take longer per file, because the tool may try several settings to find the one that fits.

For a single file of hundreds of MB, see compress a large PDF; the memory story there applies to each file in a batch too.

Where batch mode stops

1 setting for everything. The batch applies the same preset or target to every file. That is right for a folder of similar scans, and wrong for the 3 files that matter most. A contract you will print and a phone snapshot of a receipt deserve different settings, so run the important ones on their own.

The details are shortened for big batches. Every file keeps its own before-and-after line in the report, named by the file (“lease.pdf: 17.6 MB to 1.7 MB: 90 % smaller”), for up to 200 files. The finer detail (pictures re-encoded, the pages that changed most) is cut to 24 lines in all, ending with “And 40 more lines like these” or however many there are. For the full detail on 1 file, run it on its own.

Passwords are not asked for in a batch. Protected files are skipped so the run is not held up. Run each of them on its own, type its password, and note that the result has no password: protect it again with Protect PDF if it needs one.

It does not merge. The batch gives you as many files as you put in. To make 1 file out of many, use Merge PDF after compressing, and see organising PDF pages for putting them in order.

It cannot shrink what is not pictures. Fonts, typed text and drawings stay as they are, which is why typed documents barely move. For scans specifically, compressing a scanned PDF goes into resolution and readability, and make a PDF smaller covers every lever.

If you would rather do this in an installed app on Windows, compressing a PDF on Windows covers the options. Here, nothing is installed and nothing is uploaded: the folder goes from your disk, through your browser, back to your disk.