How to Join or Merge PDF Files in Minutes?
11 July 2023 Senior Product Manager
Last update by Olivia Brown at 30 January 2026
Summary
This guide details various offline and online tools to split PDF into pages. It includes step-by-step instructions for software like Renee PDF Aide and quick browser-based alternatives.
A PDF document is a versatile electronic file that can be opened on different operating systems and devices. It can store various types of information including text, fonts, graphics, videos, hyperlinks, and forms. PDF files have gained popularity and are commonly used for saving downloaded documents from the Internet.
There are two main ways to join PDFs quickly: dedicated desktop software and browser-based online tools. Below you’ll find step-by-step instructions, pros and cons, and practical tips for both approaches so you can choose the method that fits your time, privacy, and file size needs.
Comparison of Desktop Software vs Online Tools
| Attribute | Desktop Software | Online Tools |
|---|---|---|
| Speed | Fast for large files; local processing | Fast for small files; upload/download adds time |
| Privacy | High — files stay on your machine | Lower — files are uploaded to a server |
| File size / Limits | Handles large files; limited by local disk | Often capped by site limits or free tiers |
| Feature set | Rich editing, batch processing, OCR | Basic merging; some offer extra tools |
| Ease of use | More setup, more control | No install; very quick for one-off tasks |
Methods Covered in This Article
| Category | Examples Covered |
|---|---|
| Local PDF merge software | Renee PDF Aide; Adobe Acrobat DC; Mac Preview; Icecream PDF Split & Merge |
| Online PDF merge tools | LightPDF; PDF Real; Sejda; combinepdf.com |
If you frequently combine PDFs or work with sensitive files, desktop software offers speed, reliability, and privacy (no uploads). The tools below are popular choices with different strengths and pricing models.
Renee PDF Aide is a comprehensive PDF editing software that allows you to easily merge multiple PDF files into one, whether it’s all pages or individual pages. It also offers other editing tools such as format conversion, splitting/deleting multi-page files, repairing damaged files, optimizing loading time for large files, adjusting display angles, and encrypting/decrypting PDF files. Additionally, it features advanced OCR (Optical Character Recognition) technology for converting scanned PDF files or pictures into editable text format.
Renee PDF Aide - Powerful PDF Converting/Editing Tool (100 FREE Quota)
Convert to Editable Convert to Word/Excel/PPT/Text/Image/Html/Epub
Multifunctional Encrypt/decrypt/split/merge/add watermark
OCR Support Extract Text from Scanned PDFs, Images & Embedded Fonts
Quick Convert dozens of PDF files in batch
Compatible Support Windows 11/10/8/8.1/Vista/7/XP/2K
Convert to Editable Word/Excel/PPT/Text/Image/Html/Epub
OCR Support Extract Text from Scanned PDFs, Images & Embedded
Support Windows 11/10/8/8.1/Vista/7/XP/2K
The steps to merge PDF files are as follows:
① After installing and opening the software, click (PDF Tools)
② Click (Merge) > (Add File) to import the PDF file.
③ In the drop-down box on the right of “Pages to Merge“, select (All) or (Use Generator). Click “Use Generator” to manually select or use automatic merge options provided by the software. Finally, click “Convert” to export the file.
Advantages:
- Works completely offline for maximum privacy
- No file size or page limits
- Advanced OCR for scanned PDFs
- Full suite of editing tools included
- No watermarks on output
- Fast and reliable processing
Disadvantages:
- Requires download and installation
- Windows-only (no native Mac version)
If you want a dependable, privacy-friendly way to join PDFs and also handle tasks like OCR, compression, and encryption, Renee PDF Aide is a solid pick. Next, if you already use Adobe tools, consider the following option.
Adobe Acrobat DC is a comprehensive PDF application that offers viewing, creating, editing, managing, and printing capabilities. It enables merging multiple PDFs, Word documents, spreadsheets, and email attachments into a single PDF. The software also provides various editing tools like splitting PDFs, organizing pages, annotating, filling, and signing. It’s important to mention that Adobe Acrobat DC is a paid software, with a higher purchase price compared to other PDF editing software options.
Advantages:
- Excellent output quality and formatting
- Advanced page organization features
- Integrates with other Adobe tools
- Supports very large files
Disadvantages:
- Subscription-based (paid)
- More expensive than alternatives
- Requires account sign-in
The specific operation steps are as follows:
① Install and open the Adobe Acrobat DC software, click (Tools) > (Merge Files). Click (Add Files), select the files to add to the PDF, you can merge PDF or merge PDF and other files.
② After adding files, rearrange the file order by clicking and dragging or delete unnecessary files by pressing the (delete key). Once sorted, click (Merge) to start merging PDF files. Finally, click (Save button) to save to the specified location.
To combine multiple PDF files into one on your Mac, use the pre-installed “Preview” application. It allows you to merge PDFs without any additional downloads or installations. The process is straightforward, and any changes made using Preview are automatically saved. However, remember to create a copy of the original PDF if you wish to preserve it.
Advantages:
- Completely free and pre-installed
- No internet or uploads needed
- Simple and quick for basic tasks
- Changes save automatically
Disadvantages:
- Mac-only
- Limited reordering features
- No advanced options like OCR
The specific operation steps are as follows:
① In the “Preview” program on Mac, open the PDF you want to merge. Then tap (Display) > (Thumbnails) to display page thumbnails in the sidebar.
② Then, you need to indicate where to insert another PDF document, please click to select a page thumbnail. Then click (Edit) > (Insert) > (Pages (from file)), select the PDF file you want to add, and click (Open).
③ After merging, please click (File)>(Export as PDF) to save the file.
Icecream PDF Split & Merge is a powerful tool for effortlessly splitting and merging PDF files. It allows you to merge multiple PDFs into a single file, with no limit on the number of files. Furthermore, it can handle password-protected PDFs, provided you enter the correct password beforehand. This software is compatible with both Windows and Mac operating systems.
Advantages:
- Free version available
- No file number limits
- Supports encrypted PDFs
- Clean, simple interface
Disadvantages:
- Some advanced features require paid upgrade
- Basic reordering compared to pro tools
The specific operation steps are as follows:
① After installing and opening the Icecream PDF Split & Merge software, click (Merge) on the main interface.
② Click (Add file) to add the PDF files to be merged. When you have added all the files to the software, you can select the files to move and click the (↑) and (↓) buttons on the right side of the window to adjust the order of the files.
③ Click the folder icon next to (Save to folder) to set the save location of the output file. Finally, click the (MERGE) button to merge the PDF files together.
Online PDF joiners work in any modern browser and on any OS (Windows, Mac, Linux, ChromeOS). They’re ideal when you need a quick, one-off merge without installing software. Keep in mind:
- You’ll need a stable internet connection and must upload your files.
- Free services may limit file size, page count, or daily tasks.
- Check the site’s privacy policy if your PDFs include sensitive data.
If you’re comparing quick browser mergers, here’s a concise snapshot to help you decide: the table below summarizes each service’s free‑tier limits, per‑file size caps, how many files you can upload at once, retention windows, and whether free outputs include watermarks—use it to match your file sizes, privacy needs, and urgency to the right tool.
| Service | Free limits (per task) | Max file size (per file) | # files per job | Retention | Watermark (free) |
|---|---|---|---|---|---|
| LightPDF | 1 per task | 10 MB | 1 | Short | No |
| PDF Real | 1 per task | 20 MB | 1 | Short / in‑browser | No |
| Sejda | 3 tasks / hour | 50 MB or 50 pages | Multiple (subject to per‑task limits) | ~2 hours | No |
| CombinePDF | 1 task (free) | 120 MB | Up to 20 files | ~1 hour | No |
Below are popular online options and how to use them.
LightPDF offers a free online PDF merger plus editing, converting, watermarking, and compression tools. You can upload multiple PDFs, reorder them, and merge with a click. It works in major browsers such as Chrome, Safari, and Firefox. Designed for speed and simplicity, its merge PDF online page supports drag-and-drop uploads, batch selection, and quick downloads without installing anything.
Online merge link: https://lightpdf.com/zh/merge-pdf
The specific operation steps are as follows:
① Open the PDF merge link of LightPDF on the browser, click (select files) to upload the PDF documents to be merged in order.
② Finally, click (Merge). After waiting for the merge to complete, you click (Download button) to save the PDF file to your computer.
PDF Real is an easy-to-use PDF merger tool with a clean interface, and the page is free of ads and pop-up windows. You can upload multiple PDF files and quickly merge them into one PDF file.
Online Merge Link: https://pdfreal.com/merge-pdf
The specific operation steps are as follows:
① After opening PDF Real, click (Select File) to upload the PDF file. If there are three or more files to merge, click (More Files).
② After the PDF file is uploaded, click (Merge), the online tool will automatically merge the files into one file, and then automatically download the generated merged PDF.
Sejda can merge PDF and image files online, and the operation is relatively simple. Its advantage is that it provides some page settings, such as optional double-sided printing, bookmark retention and so on. The online conversion tool is limited in use, and only 50 pages or 50MB of PDF documents can be merged for free per hour.
Online Merge Link: https://www.sejda.com/merge-pdf
The specific operation steps are as follows:
① After opening the Sejda online merge link, click (Upload PDF & image files) to upload the PDF files to be merged, or upload from OneDrive, DropBox, Google Drive or enter the URL.
② After uploading the files, you can click (Merge PDF files) to quickly merge them. If you still need to optimize the document, you can click (More options). When finished, click (Merge PDF files). After merging, you can choose to download the PDF file to a local folder, save it to a cloud storage site, or share it via email.
This convenient and easy-to-use free online PDF merge tool can help you merge multiple PDFs or images into one PDF document without installing any software. It should be noted that a maximum of 20 PDF files and images can be uploaded from the computer each time for merging.
Online merge link: https://combinepdf.com/zh/
The specific operation steps are as follows:
① After opening the merge link in the browser, click (Upload Document) to upload the PDF file to be merged.
② You can drag and drop PDF file blocks to change the order, after sorting the order, please click the (Merge) button, the merged files will be downloaded automatically.
After merging PDF files, if you need to do other editing operations, then Renee PDF Aide is a good choice. Renee PDF Aide can provide PDF editing functions such as PDF conversion, splitting pages, rotating pages, adding watermarks, repairing unopenable PDFs, optimizing and compressing PDFs, encrypting/decrypting PDF files, etc.
Renee PDF Aide - Powerful PDF Converting/Editing Tool (100 FREE Quota)
Convert to Editable Convert to Word/Excel/PPT/Text/Image/Html/Epub
Multifunctional Encrypt/decrypt/split/merge/add watermark
OCR Support Extract Text from Scanned PDFs, Images & Embedded Fonts
Quick Convert dozens of PDF files in batch
Compatible Support Windows 11/10/8/8.1/Vista/7/XP/2K
Convert to Editable Word/Excel/PPT/Text/Image/Html/Epub
OCR Support Extract Text from Scanned PDFs, Images & Embedded
Support Windows 11/10/8/8.1/Vista/7/XP/2K
1 , Split PDF files
Splitting a PDF file is to split a multi-page PDF into multiple small PDF files according to requirements; or to remove redundant pages and only split out specified pages.
The specific operation steps are as follows:
① After opening the software, click (PDF Toolset).
② Click (Split) > (Add File) to import the PDF file.
③ Then, select one of the split modes. There are two split modes: split into multiple smaller files, retain specified pages (remove unnecessary).
④ Finally, click (Convert) to export the file.
2 , Rotate PDF files
If you find that the angle is incorrect after opening the PDF file, you can also adjust it through this software. Adjust the display angle of the PDF file, the angle options are 90, 180, 270.
The specific operation steps are as follows:
① After opening the software, click (PDF Toolset) > (Rotate) > (Add File) to import the PDF file.
② Select the angle to be rotated in “Angle of Rotation (Clockwise)” or “Quick Select Angle”.
③ Finally, click (Convert) to export the file.
3 , Add watermark to PDF
In order to protect the PDF file from being stolen and used by others, and to protect the ownership of the file, you can add a personal watermark to the PDF. In Renee PDF Aide, you can add foreground watermark or background watermark to PDF files. The watermark can choose images and PDF files.
The specific operation steps are as follows:
① After opening the software, click (PDF Toolset) > (Watermark) > (Add File) to import the PDF file.
② You can choose (Add watermark (cover surface)) or (Add background), and then choose (Watermark file) and (Location information).
③ Finally click (convert).
4 , Repair abnormal PDF files
Improper handling can most likely lead to various issues with PDF files such as failing to open or being corrupted. The “Repair” function of Renee PDF Aide is mainly aimed at the above two problems, helping you to fix them quickly.
The specific operation steps are as follows:
① After opening the software, click (PDF Toolset) > (Repair) > (Add File) to import the PDF file.
② Select the recovery mode, (Mode 1) or (Mode 2).
- Mode 1: Provide efficient damage repair, suitable for customers who require fast repair.
- Mode 2: Repair files more accurately and deeply, and the repair time will be longer.
③ Click (Convert) to export the repaired file.
5 , Optimize PDF files
Sometimes when you encounter a large PDF file, it will take a relatively long time to open the file. To save time, you can use the “Optimize” function to compress large PDF files so that they can be opened quickly.
The specific operation steps are as follows:
① After opening the software, click (PDF Toolset) > (Optimize) > (Add File) to import the PDF file.
② Select optimization options:
- Online page loading speed (linearize): This optimization option is suitable for web page PDFs, and the loading will be smoother after optimization.
- Compress Images: Compress images in PDF files.
- Compress data stream: Compress pdf file data stream. (PDF file capacity becomes smaller)
③ Finally click (convert).
6 , Encrypt/decrypt PDF files
In the encrypted PDF file option, you can add password protection to prevent unauthorized access and modifications. Renee PDF Aide allows you to set editing and printing permissions, including printing, modification, text and image extraction, annotation, form filling, and signature. If you forget the password, you can easily decrypt the PDF using the “Decrypt PDF” option.
Steps to encrypt PDF:
① After opening the software, click (PDF Toolset) > (Encryption & Decryption) > (Add File) to import the PDF file.
② Select (encrypt PDF file). Then please enter the encryption password and set the editing and printing permissions of the file.
③ Finally click (Convert) to export PDF.
Steps to decrypt PDF:
① Select (Decrypt PDF file)”.
② Click (Modify), and enter a possible password in the pop-up window. NOTE: Please keep one password per line.
③ Finally, click (Convert) to export PDF.
Frequently Asked Questions
Can I join or merge PDF files for free?
Yes. Free options include Mac Preview (built-in), Icecream PDF Split & Merge (desktop), and online tools like LightPDF, Sejda, and combinepdf.com. For unlimited offline use with advanced features, Renee PDF Aide offers excellent value.
Is it safe to use online tools to merge PDFs?
Online tools are convenient but require uploading files to servers, which can pose privacy risks—especially with sensitive documents. For maximum security, use desktop software like Renee PDF Aide or Mac Preview, which keep everything local.
How can I merge PDF files on a Mac without extra software?
Use the built-in Preview app: open a PDF, show thumbnails, then drag pages from another PDF into the sidebar or use Edit > Insert > Page from File. It’s fast, free, and secure.
Will merged PDFs have watermarks?
Most reputable tools (including all listed here) do not add watermarks on free or standard use. Always check the output, especially with lesser-known online services.
Can I merge password-protected PDFs?
Yes, with tools like Icecream PDF Split & Merge or Renee PDF Aide—just enter the password when prompted. Online tools usually don’t support protected files.
How do I merge scanned PDFs or images into one file?
Use a tool with OCR support like Renee PDF Aide to make scanned pages searchable after merging, or any of the listed tools that accept image uploads (Sejda and combinepdf.com work well for images).
What’s the fastest way to merge PDFs on mobile?
Most online tools (LightPDF, Sejda) are mobile-friendly—just open in your browser, upload, and download. Dedicated apps like Adobe Acrobat or SmallPDF also offer mobile merging.
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