Merge PDF online

How to merge PDF files

1. Click the file field and select two or more PDF files. Most browsers let you select multiple files at once, or add more with a second selection.
2. Check the file list to confirm you selected the files you meant to, since the merge order follows your file manager's selection order.
3. Click Merge PDFs.
4. Preview the combined file in the inline preview.
5. Download the merged PDF and open it once to confirm every source file's pages are present and in the expected order.

Pages are copied in the order the files were selected, and each file's own internal page order is preserved. If you need a specific order, select files one at a time in that order, or merge in two passes.

What merging does and how it works

Merging reads each selected PDF, copies every page from each one (preserving the original page content, fonts, and formatting) into a single new PDF document, and joins them in file-selection order. This is a structural copy operation: it does not re-render or flatten pages, so text stays selectable and vector graphics stay sharp, unlike merging by printing pages to images.

Best practices

• Check file order before merging. Browsers generally preserve the order in which you selected files, but confirm the list shown after selection matches what you expect, especially with drag-selected ranges.
• Merge related documents you'll be sharing or archiving together (a report and its appendices, several scanned pages, multiple signed forms) rather than very large unrelated batches.
• Keep your original files. Merging creates a new file; your source PDFs are not modified.

Common mistakes to avoid

• Selecting files in the wrong order and not noticing until after downloading; check the order before merging, since re-ordering afterward means starting over or using the reorder pages tool on the result.
• Merging password-protected PDFs. This tool cannot open encrypted PDFs (see the limitations below); remove protection with the file's original source or software that supports encryption first.
• Expecting merged bookmarks or a table of contents. Page content is combined, but source-file bookmarks/outlines are not automatically carried over or renumbered.

Real-world use cases

• Combining a cover letter, resume, and references into one application PDF.
• Joining scanned pages from multiple single-page scans into one document.
• Assembling a report with appendices that were authored as separate files.
• Combining multiple signed forms or invoices into a single file for one email attachment.

Supported formats

Input: standard, non-encrypted PDF files, any number of them (subject to your browser's available memory). Output: a single standard PDF file. This tool does not accept Word, image, or other non-PDF formats directly; convert those to PDF first (see JPG to PDF for images).

Worked example: combining a 3-page cover letter and a 2-page resume

Selecting cover-letter.pdf (3 pages) and resume.pdf (2 pages), in that order, produces a single 5-page merged.pdf: pages 1-3 from the cover letter followed by pages 1-2 of the resume, renumbered continuously as pages 1-5 in the new file.

If you had selected resume.pdf first instead, the output order would flip: resume pages first, then the cover letter. Always check selection order for a result that depends on it.

Limitations

This tool cannot open password-protected or encrypted PDFs; loading one will fail with an error. Extremely large PDFs (hundreds of megabytes, or very high page counts) may be slow or hit browser memory limits, since the whole operation runs in your browser's memory rather than on a server. Interactive form fields, embedded video, and some advanced PDF features may not carry over identically into the merged file, since pdf-lib focuses on standard page content.

Privacy

Selected PDF files are read and merged locally in your browser using the pdf-lib JavaScript library loaded from this site. Files are not uploaded to a server. See the privacy policy for full detail.

Troubleshooting

• If merging fails immediately, the file may be password-protected; this tool cannot open encrypted PDFs.
• If the order is wrong, redo the file selection in the order you want, or use reorder PDF pages on the merged result.
• If the merge is slow, try merging fewer or smaller files at a time.

Checking a merged file before relying on it

After merging, spend a minute checking the result rather than assuming it worked: confirm the total page count matches the sum of your source files' page counts, scroll to the boundary between each source file to make sure nothing was cut off, and check that any full-page images or diagrams near the end of one source file still display correctly at the start of the next section. This is especially worth doing for scanned documents, where a source file with a corrupted or unusual page can sometimes produce unexpected results in the merged output even though the merge operation itself completes without an error.

How this compares to printing to a PDF combiner

Some workflows "merge" PDFs by printing each one to a virtual PDF printer in sequence, or by converting every page to an image first. Both approaches re-render the content, which can blur small text, bloat file size, and make text unselectable and unsearchable in the result. Because this tool copies the original page objects directly, text in the merged file stays exactly as sharp and selectable as it was in the source files, and the file size grows roughly in proportion to the combined content rather than ballooning from image conversion.

Conclusion

Use this tool whenever you need several PDFs combined into one file, in a specific order, without uploading anything to a server. To split a merged file back apart later, use split PDF; to fix page order after merging, use reorder PDF pages.