How AFileFix's PDF merger works

AFileFix tries to merge your PDFs in your browser first. Most modern PDFs combine cleanly that way — your files never get uploaded, never touch our server, never leave your device. When the browser can't handle a particular file's structure (some older PDFs, unusual encryption schemes, or unconventional layouts), we ask before falling back to server processing. You stay in control either way.

The browser-first approach also unlocks features that fully server-based tools can't easily offer: automatic bookmarks per merged file, drag-to-reorder with instant feedback, and merge cancellation mid-flow without abandoning a server job.

Does AFileFix upload my files when I merge?

Usually, no. Most merges run entirely in your browser, meaning your PDFs are processed on your own device and never sent to our server. There's no upload, no remote processing, no retention concerns.

The exception is when a PDF has a structure our browser-side library can't handle — typically older PDF versions, certain encryption variants, or unusually complex documents. In that case, you'll see a clear dialog: "[filename] has an incompatible structure that can't be merged in your browser. We can merge them securely on our server instead." You can accept the server merge or cancel and remove the problem file. We never upload silently.

If you do accept the server merge: files are uploaded over HTTPS, merged on our server, and deleted within minutes. They're never archived, logged, or used for training.

For sensitive documents where the difference matters — legal filings, medical records, internal contracts — we recommend confirming all files merge in your browser before relying on AFileFix for that workflow. If one consistently triggers server fallback, you'll know to handle it differently.

How do I merge PDFs with AFileFix?

1. Add your PDFs. Drop multiple files onto the upload area (or click to browse). You can also add more files later from the editor view. Each file can be up to 50 MB; the total batch can be up to 200 MB.
2. Reorder if needed. Drag the handle on the left of each file to rearrange the order, or use the up/down arrows. You can also use the "Reverse" toggle in the sidebar to flip the order all at once — useful for scanned documents or log files captured in reverse-chronological order.
3. Configure (optional). AFileFix adds a bookmark per merged file by default, so your final PDF has a clickable outline showing where each source file begins. Toggle off if you'd rather have a flat merged document.
4. Click Merge. For most PDFs, the merge happens in your browser — you'll see step-by-step progress. If one of your files needs server processing, we'll ask for permission first. You can cancel the merge at any point during processing.
5. Download. The result downloads as merged.pdf. If the merge ran in your browser, your files were never uploaded. If a server fallback was used, your files have already been deleted.

What does the consent dialog actually say?

When a server fallback is required, you see a dialog with this exact wording:

"[filename] has an incompatible structure that can't be merged in your browser. We can merge them securely on our server instead. Your files will be uploaded over HTTPS and deleted within minutes after merging."

Two buttons: "Merge on Server" (which uploads and merges) and "Cancel — I'll remove the problem files" (which closes the dialog without uploading). The dialog can't be dismissed by clicking outside it — you have to make a clear choice.

There's no default selection. There's no "remember my choice." There's no auto-upload after a timeout. The decision is yours every time.

Automatic bookmarks for navigation

When you merge PDFs in your browser, AFileFix automatically generates a bookmark for each source file using the filename. Open the result in any PDF reader and the outline panel shows a clickable list — "Invoice-March.pdf," "Invoice-April.pdf," "Invoice-May.pdf," each linking to the first page of that section.

This is useful for:

• Expense reports — receipts merged into one PDF with bookmarks per vendor
• Document portfolios — applications, contracts, or evidence bundles where reviewers need to jump between sections
• Multi-author submissions — assembling chapters or report sections where you want to preserve the source structure
• Reference collections — research papers or notes merged for sharing with section navigation intact

You can toggle bookmarks off in the sidebar if you prefer a flat document. The toggle defaults to on because most users benefit from the navigation, and the feature adds essentially no file size overhead.

One caveat: bookmarks are only added when the merge runs in your browser. If a file in your batch requires server fallback, the entire merge moves to the server, and the server path doesn't generate filename-based bookmarks. If bookmarks matter for your use case, make sure none of your files triggers fallback.

What types of PDFs work best with AFileFix Merge?

Best results: Modern PDFs (created in the last decade, version 1.4 or higher). Standard documents, exports from Office, Google Workspace, or contemporary design tools. These merge in your browser cleanly, get automatic bookmarks, and never leave your device.

Modest results: PDFs with complex form structures, unusual encryption, or older PDF versions. These may still merge browser-side, or may trigger the server-fallback consent dialog. Server merge works fine but skips the bookmark generation.

Not supported:

• Password-protected PDFs. Detected at upload — you'll be redirected to AFileFix's Unlock PDF tool first. Once unlocked, you can merge the result.
• Non-PDF files. Only PDF files can be merged. If you need to include images or Word documents, convert them to PDF first using Image to PDF or PDF to Word's reverse equivalent.
• Mixed page-level merges. AFileFix merges complete files. If you need only certain pages from a source PDF, use Split PDF or Delete Pages first, then merge the trimmed files.

Frequently asked questions