Why did compression barely change my file size?

The compressor only re-encodes embedded JPEG image streams. A PDF built from text, vector drawings or Flate-encoded bitmaps has no JPEGs to squeeze, so it comes out much the same size. Dropping pages is the reliable lever on that kind of file.

Does compressing a PDF damage the text?

No. Only JPEG image streams are re-encoded. Vector text and other page content are left untouched, so the document stays selectable and searchable at any quality setting.

What quality setting should I use?

Start at the default of 75%. For scanned paperwork that only has to be legible, try 50 to 60% with Max image dimension set to Small — 1200px. Below roughly 40% the JPEG blocking starts to show on scanned text.

Is my PDF uploaded anywhere?

No. Split PDF, Extract PDF Images and the PDF Editor all read the file inside the browser tab and write the result straight back to your machine. There is no account, no server-side processing and no queue.

Does password-protecting the PDF make it bigger?

Slightly. An encrypted export is written without object streams, because some readers mishandle encrypted ones, and that costs a little structural compression. Turn encryption on only when you actually need it.

Shrink a PDF to Fit an Email Limit

Get a PDF under your mail server's attachment cap in the browser: drop the pages you don't need, recompress its embedded JPEGs, and strip the extras.