Merge PDF
Combine multiple PDF files into one document. Drag to reorder before merging.
Drop files here or click to upload
.pdf · Max 100 files
Or paste files with Ctrl+V
Your files never leave your browser
What is PDF Merge?
Merge PDF combines two or more PDF files into a single document while preserving the original page order, formatting, embedded fonts and quality. The whole operation runs inside your browser using pdf-lib — your PDFs are never uploaded.
How to use PDF Merge
- Drop or select the PDF files you want to combine (up to 100 at a time).
- Drag the files in the queue to set the merge order.
- Click "Merge" — pdf-lib stitches the documents together.
- Download the resulting single PDF.
Why use AinnoBox for this
- Page order follows your queue exactly — drag to rearrange before merging, with no surprise re-sorting by filename.
- Pages are copied object-for-object rather than re-rendered, so text stays selectable and vector graphics stay sharp.
- Up to 100 documents in a single pass, with no per-file size ceiling beyond your own device memory.
- Merging happens in a Web Worker on your machine, so confidential contracts never sit in an upload queue on someone else's server.
- No sign-up, no email, and no watermark stamped onto the merged file.
PDF Merge — frequently asked questions
- Does merging reduce quality or increase file size?
- Neither. Pages are copied with their existing encoding, so images are not re-compressed and text is not rasterised. The merged file is normally close to the sum of the inputs, minus a little overhead that is shared once instead of per file.
- Are bookmarks, form fields and annotations preserved?
- Page content, embedded fonts and images carry over. Document-level structures — outlines/bookmarks, AcroForm fields and some annotation types — do not, because every page is copied into a brand-new empty document. If you need a bookmarked master file, add the outline after merging in a full PDF editor.
- Can I merge a password-protected PDF?
- No. Encrypted documents are rejected with an "encrypted or invalid" error rather than being silently skipped. Remove the password in the application that produced the file, then merge the unlocked copy.
- How large a file can I merge?
- We impose no limit. The practical ceiling is your device RAM, because the whole document is held in memory while it is assembled. On a typical laptop several hundred megabytes of combined input is comfortable.
Want to understand why AinnoBox processes everything in the browser rather than on servers? Read How It Works or check the FAQ.