Merge PDFs into one file under a KB limit
Combine PDFs into one file under 200KB, 500KB or 2MB. Runs in your browser — files are never uploaded.
10 to 20000 KB. Leave empty for no limit.
If the merged file is over the limit, its pages are turned into images to fit, and text can then no longer be selected.
How it works
Add your PDFs, and JPG or PNG scans if you need them, then put them in order: drag a file, or use its Up and Down buttons (Alt + arrow keys also work on a focused button). The tool first joins the pages as they are, so their text stays selectable. If that file is under your limit, you get it unchanged. Only when it is too big does the tool turn every page into a JPG image and search for the sharpest resolution and quality that fits, from about 108 dpi down to about 22 dpi; long documents start lower to fit in memory, and very large ones cannot be compressed. Each image file becomes one page, sized to fit A4. Sizes use 1 KB = 1,000 bytes, so the result also fits portals that count 1 KB as 1,024 bytes.
Questions
Are my files uploaded?
No. Your files are read and merged inside your browser and stay on your device. The page loads its PDF tools (pdf-lib, pdf.js and jsPDF) from cdnjs, but your files are never sent.
Why did my text become an image?
Merging adds the sizes of all files together, so several documents often go over a portal limit. Turning pages into images is what makes small sizes possible. If you need selectable text, raise the limit or leave out pages you do not need. To shrink one PDF on its own, use compress PDF to exact KB.
Can I merge a signed or password-protected PDF?
A digitally signed PDF can be added, but its signature is no longer valid in the merged file, because any change to a signed document breaks it. If the portal checks signatures, upload the signed file on its own. PDFs with a password or editing restrictions cannot be added; save a copy without protection in your PDF reader first.
What is not kept?
Bookmarks are dropped, links between pages may stop working, and fillable form fields may no longer be fillable. If the limit cannot be reached even at the lowest setting, the tool tells you the smallest size it made. Many pages can be slow, or fail, on a phone.
I only have photos or scans. What should I use?
Use images to PDF under a KB limit. It also has options such as two or four images on one page.