Merging runs locally with pdf-lib and PDF.js previews. PDFs are not uploaded to a server. Password-protected files must be unlocked first. Max 20 files, 100 MB total.
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PDF merging joins the page trees of multiple PDF documents into one output file. Each source document contributes its pages in sequence, and the resulting PDF contains all of them in the exact order you choose.
Browser-based PDF merging — like this tool — processes files entirely in JavaScript using the pdf-lib library. Your files are never uploaded to a server, which matters for contracts, medical records, legal documents, and any file you would not upload to a third-party service.
A merged PDF is a new document; the originals are untouched. Merging is different from inserting pages into an existing document and different from splitting a document into smaller files.
Click 'Add PDFs' or drag and drop multiple PDF files into the upload area. You can add up to 20 files with a combined total of 100 MB.
Drag file cards or use arrows to reorder. Use Reverse or Sort A–Z for quick changes. Lock files to pin cover pages while you sort the rest. The document outline shows page ranges in the final PDF.
Review the preview summary, set an output filename if needed, then click Merge PDFs (or press Ctrl+Enter). Processing runs locally with pdf-lib.
Review the before/after summary on the success screen, download the merged PDF, or return to the editor to adjust order and merge again.
Common real-world scenarios where this tool saves time.
Combine resume, cover letter, and portfolio into one PDF before submitting to employer portals that accept only one file attachment.
Merge multiple agreement pages, appendices, and signature sheets into one sendable document for clean contract management.
Combine monthly reports, charts, and data exports from different tools into one presentation-ready PDF for stakeholders.
Merge lecture slides, notes, and supplementary PDFs into one file for offline reading and organised revision.
Step-by-step chains that connect related tools for common tasks.
Many portals accept one PDF but enforce a 1–2 MB cap. Assemble first, then compress — merging does not shrink file size.
The standard sequence when combining files from multiple sources.
Input
File 1: resume.pdf (1 page) · File 2: cover-letter.pdf (1 page) · File 3: portfolio.pdf (4 pages)Output
job-application.pdf · 6 pages total · Resume on page 1, Cover letter on page 2, Portfolio on pages 3–6Many employer portals accept only one PDF attachment. Merging resume, cover letter, and portfolio in that order creates a single professional document. Drag the tiles to set the order before merging — the final PDF reflects exactly the sequence shown.
Input
File 1: financial-summary.pdf (3 pages) · File 2: sales-charts.pdf (5 pages) · File 3: appendix-data.pdf (12 pages)Output
monthly-report-may-2026.pdf · 20 pages totalFinance and operations teams routinely export reports from separate tools (Excel, Tableau, database exports) as individual PDFs. Merging creates one distribution-ready document for stakeholders without manual copy-paste or re-export.
Input
File 1: agreement-body.pdf (8 pages) · File 2: schedule-a-exhibits.pdf (6 pages) · File 3: signature-page.pdf (1 page)Output
contract-final.pdf · 15 pages totalLegal teams often draft agreement body, exhibits, and signature pages separately. The merged PDF preserves all hyperlinks (including internal cross-references) and embedded fonts so the final contract prints and displays correctly.
This tool uses pdf-lib, an open-source JavaScript library for creating and modifying PDFs in browser and Node.js environments. When you click Merge, each source PDF is read as an ArrayBuffer, parsed into a PDFDocument object, and its pages are copied into a new PDFDocument using copyPages(). The final document is serialized as a Uint8Array and offered as a file download.
Formula
const merged = await PDFDocument.create();
for (const file of files) {
const src = await PDFDocument.load(arrayBuffer);
const pages = await merged.copyPages(src, src.getPageIndices());
pages.forEach(p => merged.addPage(p));
}
const bytes = await merged.save();Each operation transforms a PDF in a different way — choose based on your specific task.
| Operation | What it does | Use when |
|---|---|---|
| Merge | Combines multiple PDFs into one file | Assembling multi-part documents for submission or sharing |
| Split | Divides one PDF into multiple files | Breaking a large document into chapters or individual pages |
| Extract pages | Copies specific pages into a new PDF | Pulling the 3-page summary out of a 50-page report |
| Remove pages | Deletes specified pages from a PDF | Removing a cover page or blank page before sharing |
| Compress | Reduces file size by compressing embedded images | Reducing size before emailing or uploading |
You can chain operations: compress each PDF first, then merge the smaller files for a faster, lighter output.
Where processing happens affects privacy, speed, and file size limits.
| Factor | Browser-based (this tool) | Server-based tools |
|---|---|---|
| Privacy | Files never leave your device | Files uploaded to third-party servers |
| File size limit | Browser memory (~1 GB practical) | Tool-specific, often 25–100 MB |
| Speed | Fast for files up to ~50 MB combined | Depends on upload speed and server queue |
| Offline use | Works without internet after page loads | Requires internet connection |
| Advanced features | Limited to pdf-lib capabilities | OCR, form creation, digital signatures available |
| Cost | Free, no signup required | Often freemium with page or size limits |
Use Merge PDF to join multiple documents in the order you choose. Use Split PDF or Extract PDF pages when you need separate files instead of one combined output.
| Related tool | Use this tool when | Use related tool when |
|---|---|---|
| Split PDF | You have several PDFs and need one file for email, a portal upload, or printing. | You have one large PDF and need chapters or page ranges as separate downloads. |
| Extract PDF Pages | You want every page from each source file combined in sequence. | You only need specific pages from one or more PDFs—not the full documents. |
| Compress PDF | You are assembling multi-part reports or application packets in order. | The merged PDF is too large to email—compress after merging to shrink image-heavy output. |
| Reorder PDF Pages | Each source file is already in the right internal order; you only need to join files. | Pages inside a single PDF need rearranging before or after you merge with other files. |
Merging preserves file sizes — a 10 MB + 8 MB merge produces roughly 18 MB output. Compressing sources first reduces the merged file, which is important for email attachments with size limits.
A rotated, blank, or corrupted page in a source file will appear in the merged output. Verify each file in a PDF viewer before merging to avoid sending a document with unexpected pages.
PDF form field names must be globally unique within a document. Merging two forms with the same field names creates conflicts that may make both sets of form data unreadable.
A quick page count check — sum of source pages equals merged page count — takes 5 seconds and catches silent failures before you send or submit the document.
The merged PDF follows your file list order exactly. Review the sequence in the tool before clicking Merge — drag tiles to reorder. The most common error is forgetting to put the cover page first.
Encrypted PDFs cannot be parsed by pdf-lib without the password. If you own the file, use a PDF password remover tool first, then re-merge the unlocked versions.
After downloading the merged PDF, confirm the page count matches the sum of your source files. If pages are missing, one source PDF may have been corrupted or used an incompatible PDF version.
PDF form field names must be globally unique within a document. Merging two forms that both have fields named 'signature' or 'date' creates conflicts that can make all form data unreadable. Fill and flatten forms before merging.
Browser-based PDF processing is memory-intensive. Source PDFs above 50 MB can cause slow processing or out-of-memory errors on phones. Compress each PDF first to reduce size, then merge.
Likely cause: One source PDF was corrupted, password-protected, or uses PDF 2.0 features not yet fully supported by pdf-lib
Fix: Test each source PDF individually in a PDF viewer to confirm they are all readable. Re-export any corrupted file from its original application (Word, Excel, scanner app).
Likely cause: Source PDFs have rotation metadata set (e.g., scanned pages with a rotation flag that the viewer corrects). pdf-lib preserves the raw metadata.
Fix: Use the Rotate PDF tool to normalize each source file to 0° rotation before merging.
Likely cause: Browser pop-up blocker intercepted the download, the combined file size exceeded browser memory, or one file failed to parse silently
Fix: Disable pop-up blocking for this site. Try merging two small files first to isolate whether it is a parsing or memory issue. Refreshing and re-adding files usually resolves transient failures.
Likely cause: pdf-lib saves with minimal stream compression when merging, even if source files were heavily compressed
Fix: After merging, run the Compress PDF tool on the output. This typically reduces size by 20–60% depending on how much image content the PDF contains.
Likely cause: Some PDF viewers (Adobe Acrobat) auto-repair minor structural variations in pdf-lib output for unusual source file structures
Fix: Accept the repair — the page content is intact. If the repaired version looks different from expected, check that source PDFs are not malformed.
Up to 20 PDF files per session with a combined total size of 100 MB. For larger batches, split into multiple merge sessions and merge the results.
Yes. Text, images, hyperlinks, and embedded fonts are preserved. PDFs with interactive forms or DRM encryption may have limitations — see the troubleshooting section.
Yes. Drag and drop the file cards in the list to set the exact order. The merged document follows the order you set.
Yes — completely free with no signup, no watermarks on output, and no usage limits.
No — merging preserves original page content. The output size is approximately the sum of source file sizes (or slightly larger). To reduce the merged file size, run it through the Compress PDF tool after merging.
External hyperlinks (URLs) and internal bookmarks within each source document are preserved. However, links that crossed between separate documents before merging will not automatically resolve to the correct pages in the merged output.
Yes. Scanned PDFs are image-based and merge normally — the image content is copied exactly. Note that scanned PDFs do not contain selectable text unless OCR was run on them. Merging does not add OCR capability.
The terms are interchangeable. Both refer to joining multiple PDF files into one. 'Combining' is Adobe Acrobat's terminology; 'merging' is used by most other tools. There is no functional difference.
Not directly — this tool only accepts PDF files. Convert Word documents to PDF first (File → Export → PDF in Word) and convert images using the Image to PDF tool, then merge the resulting PDFs here.
No. Merging runs entirely in your browser with pdf-lib. Your files are read from your device memory and the combined PDF is downloaded locally—they are not sent to EverydayTools servers for normal use.
No. Merging copies existing page content into a new file—it does not recompress images or rasterize text. Output quality matches your source PDFs. File size is usually close to the sum of inputs; use Compress PDF afterward if you need a smaller file.
Open this page in a modern browser (Chrome, Edge, Firefox, Safari), add your PDFs, drag to set order, and click Merge. No Acrobat install or account is required—processing happens locally when your browser supports it.
Not directly. pdf-lib cannot read encrypted PDFs without the user password. First unlock the protected PDF in your PDF reader (enter the password and save an unprotected copy), then add the unlocked file to the merge queue. Do not share unlocked copies of documents you are not authorized to share.
Internal hyperlinks and page-level bookmarks within each source document are preserved. However, document-level outlines (the bookmark tree in Acrobat's left panel) are not merged into a unified table of contents — each source's bookmarks reference its own page numbering. Use a full PDF editor if you need a combined bookmark hierarchy.
All PDF merging runs in your browser using pdf-lib, an open-source JavaScript library. Your files are never uploaded to any server. Safe for confidential contracts, medical records, legal documents, and any private content.
pdf-lib copies page content byte-for-byte from source documents. Text, images, vector graphics, and hyperlinks are preserved. Interactive form fields are preserved but may behave differently if field names overlap across source documents.
Always verify the merged PDF before submitting for legal, medical, or formal purposes. Confirm page count, order, and content against your source files.
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Reviewed by EverydayTools Editorial Team on 2026-06-02.
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Combine contracts, reports, or scans into one file—reorder before you merge.
PDF only · up to 20 files · 100 MB total
Processed in your browser—nothing is uploaded