“Zipping them together” and “making them smaller” are two different things
When people want to shrink several files, the first idea is often to put them in a ZIP archive — but for PowerPoint and PDF that barely helps. Once you know why, the right way to shrink them becomes clear.
Inside, pptx, docx, and xlsx files are already ZIP archives, and most images in PDFs are already compressed (JPEG and the like). Wrapping something already compressed in another ZIP changes the size almost not at all. A ZIP is for bundling files into one so they're easy to send — it does nothing to make the contents lighter.
The main reason files get heavy is high-resolution photos, scanned images, and pasted screenshots. Sveltiq opens each file and re-compresses only the images inside, so text and layout stay exactly as they are while the file itself gets smaller. Doing this to many files at once is what “batch compression” means.
If your goal is to hand someone a whole folder, the order matters. Shrink everything first, then bundle it into a ZIP, and you get both tidiness and a small size. Sveltiq can also save the results as a single ZIP after compression, so this whole flow finishes on one screen.