Every visa application ends the same way. The portal asks for your passport, your insurance letter, and your bank statement as one PDF, no larger than 2 MB. Your phone's scans add up to nine.
So you search "merge PDF online free". The first result takes your files, merges them on someone else's server, and gives you a download. It works. It is also the moment your passport, your address, and your bank details were uploaded to a company you had never heard of thirty seconds earlier.
What Catadoc does instead
Select the documents, in the order the portal wants them. Choose the cap: 10 MB for email, 2 MB for portals, or type your own. Catadoc builds one PDF on the phone, compressing page by page until it fits.
- Fully offline. The merge and the compression happen on the device. Airplane mode works fine.
- Honest about quality. If the target forces visible degradation, it warns you before you send, not after the embassy complains.
- Honest about limits. If a target is impossible, it tells you the smallest achievable size instead of silently failing.
Why this is hard enough that most apps upload
Hitting an exact size budget means re-encoding every page repeatedly, trading resolution against quality until the whole document fits. Servers make that easy. Doing it on a phone without freezing the app took us longer to build, and it was worth it: the file with your passport in it is assembled in your pocket and goes exactly one place, the portal you chose.