Drag files or click to select
You can convert 3 files up to 10 MB each
Drag files or click to select
You can convert 3 files up to 10 MB each
What is PDF merging?
Merging PDF (also called "combining" or "joining") is the process of glueing multiple PDF files together into a single document. All pages from each input file are preserved in the order you set during upload: pages from the first file come first, then the second, and so on. Text, images, hyperlinks, table of contents, and metadata are kept intact in most cases — our service does not re-encode content or rasterize pages.
Merging is useful when you need to assemble a set of documents into a single deliverable: contract + appendices + minutes, book chapters into one volume, scanned book pages into one file, exports from different systems into one report. A single file is easier to email, attach to a ticket, or upload to cloud storage than 5-10 separate PDFs.
How our service works
Simple: upload 2-10 PDF files, optionally drag them into the correct order, click "Merge" — receive one PDF that you download immediately. No registration required, no watermarks, file size limit depends on your plan.
Drag-and-drop reorder
After upload, files appear as a list. Each file has a handle icon on the left — grab it with mouse or finger on touchscreen and drag the file up/down to change position. The list order = the order of pages in the final PDF. This is especially useful when you didn't upload files in the desired sequence or want to insert a document into the middle.
What happens on the server
Under the hood we use pdfunite from poppler-utils — the standard Linux tool for PDF merging. It works at the PDF object model level: pages are copied as-is, without re-compression or quality loss. Merging 10 files totaling 50 MB usually takes less than 5 seconds.
Security
All files are uploaded over secure HTTPS. After conversion completes, files are automatically removed from servers within 24 hours (free tier). Nobody but you has access to uploaded files — each task has a unique single-use identifier.
When you need to merge PDFs
Legal documents
Contract, appendices, minutes — each often comes as a separate PDF. Before sending to a counterparty or filing in court, they need to be combined into one file with proper page numbering. Merging preserves fonts, digital signatures (with caveats), watermarks, and bookmarks.
Academic and research
Book chapters, lectures, articles, source extracts — students or researchers often work with dozens of PDFs. Combining them into one volume simplifies reading, search, and archiving.
Accounting and reporting
Invoices, work-completion certificates, monthly bank statements — combining them into one PDF and sending to accounting is faster than uploading each file separately.
Photo albums and portfolios
If you have a set of PDF pages with photos or design works — combine them into a single portfolio for sending to a client or employer.
Technical details
Container structure
A PDF (Portable Document Format) is a container made of objects: pages, images, fonts, annotations, bookmarks, metadata. Each object has a unique identifier and may reference other objects. When merging, our tool copies all objects from input files into a new file, updating identifiers to avoid conflicts.
What is preserved
- Text — copied as-is, searchable and copyable in the output file.
- Images — embedded raster images are copied without re-encoding.
- Fonts — embedded fonts are preserved, the document looks identical on any device.
- Hyperlinks — internal links to pages within the same source file continue to work; external website links too.
- Metadata — author, creation date, subject of the first file usually become metadata of the result.
What may be lost
- Bookmarks — some versions of
pdfunitedon't combine bookmarks from different files; this is a known limitation. - Digital signatures — signatures become invalid after merging (this is a PDF spec property, not our service).
- Interactive forms — form fields from different files may conflict by name.
- Password-protected files — must be decrypted first before merging.
Limits and constraints
| Plan | Single PDF size | Files per task | Daily conversions |
|---|---|---|---|
| Guest | up to 10 MB | up to 10 | 3 |
| Free (signed in) | up to 25 MB | up to 10 | 5 |
| Start | up to 100 MB | up to 10 | 100 |
| Standard | up to 500 MB | up to 10 | 1000 |
| Business | unlimited | up to 10 | unlimited |
Exact limits are on the pricing page. If your merged PDF is too large — try our PDF compression tool.
Server-side merge alternatives
- Adobe Acrobat — desktop application, paid subscription from $20/mo. Full process control, bookmark and metadata editing. Makes sense for professionals.
- Foxit / PDF24 — free desktop programs, require installation. Good for frequent work with many files.
- Browser extensions — work locally without uploading to a server. Good for confidential documents, but usually support only small files and are slower.
- Command line —
pdfunite,qpdf,ghostscript— for those comfortable in a terminal. Free, flexible, but requires learning.
Our online service is best when you need to quickly merge files without installing software, from any device — desktop, laptop, tablet, or smartphone.
What is PDF to PDF conversion used for
Contract with appendices
Combine the main contract and all appendices, certificates, minutes into one PDF before sending to a counterparty or archiving.
Book chapters into one volume
If a book is split into separate PDFs by chapter — merge them into one file for easy reading and search.
Scanned documents
Each page of a scanned document is saved as a separate PDF — combine them into one file for archiving.
Financial reporting
Invoices, certificates, bank statements for a period — sending one PDF to accounting or tax authorities is easier than many.
Designer portfolio
Combine pages with projects into one portfolio for sending to a client or uploading to a freelance platform.
Tips for converting PDF to PDF
Verify order before merging
Use drag-and-drop in the interface to arrange files in the correct order. Reordering after merging requires splitting and re-joining — extra work.
Don't merge files with conflicting forms
If source PDFs have interactive form fields with the same names — they may not work after merging. Export form data first, then merge.
Compress the result if it's large
After merging 10 PDFs, the file may exceed 50 MB. If size matters (e.g. email attachment limit of 25 MB) — run it through compression.
Keep originals until verified
Don't delete source PDFs immediately after merging — first check that all pages are present in the result, numbering is correct, and links work.
Encrypt sensitive documents before sending
If the merged PDF contains confidential info (contracts, passport data) — set a password on the downloaded file locally via Adobe Reader or alternatives.