How to Merge and Compress PDFs Safely
Job applications, invoices, contracts and scanned ID all end up as PDFs that need combining or shrinking before you send them. The usual advice is to use any online tool, but many require you to upload the file to their server first.
Why privacy matters
When you upload a document, a copy sits on someone else's server for an unknown time. For anything with personal or financial details, prefer a tool that works locally in your browser. Our PDF toolkit processes files on your device.
How to merge PDFs
- Rename files with numbers (01, 02, 03) so the order is obvious.
- Add them to the merge tool in that order.
- Merge, then open the result and scroll through every page.
How to reduce PDF size
- Compress to cut image weight, which is usually the biggest part of a scanned PDF.
- Remove unneeded pages by splitting out only what you need.
- Rescan at lower resolution if the original was captured at very high quality; 150 to 200 DPI is enough for reading.
Fix common problems
- Sideways pages: rotate them before merging.
- Email size limit: compress first, then split into parts if still too large.
- Sensitive drafts: add a "Confidential" or "Draft" watermark.
Before you send
Keep the original, check each page of the final file, and confirm the file name does not reveal private information.
Frequently asked questions
Can I merge PDFs on my phone?
Yes. The Merge PDF tool works in Chrome, Safari and other mobile browsers. Choose your files, check the order with the up and down arrows, and download the merged file. Nothing is uploaded, so it works the same on a phone as on a computer.
Is there a limit on the number of PDFs I can merge?
The site sets no limit. The only limit is your device memory, because the merging happens in your browser. Dozens of normal documents are fine on any recent phone. For hundreds of large scanned pages, a computer is more comfortable.
Why did my PDF not get smaller after compressing?
A PDF made of real text, such as one exported from Word, is often already small, so there is little to remove and you get your original back. Scanned PDFs shrink a lot. If a scan barely shrinks, try the Extreme level or Strong mode.
Does compressing a PDF reduce its quality?
Strong mode turns each page into a JPG image, so text becomes slightly softer and cannot be selected or searched. That is fine for scans and certificates. For contracts or reports you need to search, use Recommended mode, which keeps the text as text.
Is it safe to merge private documents online?
It depends on the tool. Many sites upload your files to their server. Our PDF toolkit does the work inside your browser, so bank statements, ID cards and contracts never leave your device.
Use the free PDF Toolkit to merge, split, rotate, watermark and compress.