The privacy problem with online mergers
A typical "merge PDF" website uploads every file you add, combines them on its servers, and lets you download the result. For a visa or rental application that might mean uploading your passport, birth certificate, payslips, bank statements and your partner's documents, all to a service you know nothing about. Even with a promise to delete files after an hour, you are relying on its security and honesty. Merging is a simple operation that a browser can do itself, so there is no need to take that risk.
How local merging works
This site's merger uses pdf-lib, an open-source PDF library, running in a background worker inside your browser tab. When you add files, they are read into the tab's memory; pdf.js draws a thumbnail of each first page. When you click Merge, pages are copied from each file into a new PDF in your order, and the result is offered as a download. No file leaves your computer at any point; you can confirm that in your browser's network panel, and the tool keeps working offline.
Building a good evidence bundle
- Follow the requested order. If the agency has a checklist, order the files to match it. Otherwise: identity first, then the main evidence, then supporting documents.
- One category per file where the portal asks for categories. Many portals have upload slots by category; a single giant PDF can end up in the wrong one.
- Include only the pages needed. Use the page list against each file (for example 1-2 for the first two pages of a statement).
- Fix orientation with the per-file rotate button, so the assessor is not turning their head.
- Number the pages with Add page numbers after merging, so your cover letter can refer to "page 7".
- Check the size against the portal's limit and compress if needed.
Certified copies and signatures
Merging copies pages exactly: certified stamps, signatures and annotations come through unchanged. Do not compress certified copies more than necessary; stamps can become illegible at very low resolutions. If a certification was done across two pages, keep them adjacent.
Checking nothing is uploaded
Open the browser's developer tools (F12), go to the Network tab, and merge two files. The only requests are the page's own files; none carries your documents. For a stronger test, set the network to Offline in the same panel and merge again; it still works. The site's privacy proof page lists every host the site may contact.
Limits
The free version merges up to five files of up to 50 MB each at a time; merge the result with more files to go further. PDF Pro allows up to 100 files with no size limit beyond your device's memory. Very large merges can exceed what a browser tab is allowed to use; if that happens, merge in halves and then merge the halves.
On a phone
Merging works in a phone's browser as well. Select the files from Files or Downloads, order them with the arrow buttons, and merge. The combined PDF is saved to your device, ready to attach or upload, and none of the documents leave the phone along the way. For long bundles, merge on a computer if you have one, because phones allow a browser tab less memory.
If the merged file is too big
Merging adds file sizes together. If the bundle is over a portal's limit, compress it with a target size, or split it back into categories that each fit. Both run in the browser in the same way.
Keeping the originals
Merging never changes the source files. Keep them, so you can rebuild the bundle if a document needs replacing or the portal asks for files separately.