How many PDF files can I merge at once?
PurePDF supports merging up to 20 PDF files in a single operation, with a combined total size of up to 200 MB. Each individual file can be up to 100 MB. For most use cases — combining a few reports, invoices, or document sections — this is more than sufficient. If you need to merge more than 20 files, you can merge them in batches: merge the first 20 into one PDF, then merge that result with the next batch.
Can I reorder the PDFs before merging?
Yes. After adding your PDF files, they appear in a list with ↑ and ↓ buttons next to each entry. You can move files up or down to change their order — the final merged PDF will have pages from files in the order shown. A thumbnail of each file's first page is displayed to help you visually confirm the sequence before merging. The order can be adjusted as many times as you like before clicking the Merge button.
Does merging PDFs with PurePDF preserve the original formatting?
PurePDF merges PDFs by rendering each page to a canvas and re-encoding it as a raster image. This means the visual appearance of each page is preserved exactly as it looks in a PDF reader, but underlying vector data, selectable text, embedded fonts, and document metadata are not carried forward in the merged output. If you need to maintain text selectability and searchability across all merged pages, a desktop PDF editor with native vector merging capability is more appropriate.
Is there a difference between merging and appending PDFs?
In most common usage, "merging" and "appending" mean the same thing: combining multiple PDFs so that the pages of each file follow one after another in the output. PurePDF's merger appends files in sequence — all pages of the first file, then all pages of the second, and so on. There is no page-interleaving or selective extraction during the merge operation. If you need to interleave pages (for example, alternating odd and even pages from two scanned files), you would need a more specialized PDF editing tool.
Are my PDF files uploaded to a server when merging?
No. All merging happens locally in your browser. Each PDF is loaded into memory using PDF.js, its pages are rendered to canvas elements, and the resulting images are packaged into a single new PDF using pdf-lib — all without any network transmission. Your files never leave your device. This makes PurePDF's merger safe for confidential documents, legal contracts, financial filings, and any PDF content that should remain private.
Can I merge PDFs with different page sizes?
Yes. PurePDF handles PDFs with mixed page sizes and orientations. Each page is rendered at its natural dimensions — a landscape A3 page from one file and a portrait A4 page from another will both appear correctly in the merged output. The pages are not resized or normalized to a common size during merging. This is useful when combining documents from different sources that were prepared for different paper sizes, such as reports and appendices.
Does the PDF merger work with scanned documents?
Yes. Scanned PDFs are PDFs that contain raster images as page content, and they work exactly like any other PDF in PurePDF. The pages are rendered through PDF.js, which correctly handles embedded scan images. The merged output will display each scanned page in the order you specified. Keep in mind that because PurePDF re-renders pages as images, any OCR text layer that was embedded in the original scanned PDF will not be preserved in the merged output.
What happens to bookmarks and hyperlinks when PDFs are merged?
Bookmarks (document outlines), internal hyperlinks, and interactive form fields are not preserved when merging with PurePDF. Because the merge process re-renders pages as raster images, all interactive elements — including clickable table of contents entries, internal cross-references, and external URL links — are baked into the visual layer and lose their interactivity. Annotations and comments embedded in the source PDFs are also not carried over. For merging PDFs while preserving interactive elements, a desktop PDF editor like Adobe Acrobat or PDFsam is required.
Does merging PDFs with PurePDF reduce the output quality?
The output quality is controlled by the internal JPEG render quality setting. By default, pages are rendered at high quality so the merged PDF looks visually identical to the originals when viewed at normal zoom levels. Zooming in very closely may reveal subtle JPEG compression artifacts that are not present in the original vector-based PDFs. For most professional use cases — submitting combined reports, archiving multi-part documents, or sharing assembled scans — the output quality is fully satisfactory.
Can I merge a PDF with a password-protected file?
Not currently. PurePDF's merger requires all source PDFs to be unlocked before they can be merged. If one of the PDFs you need to merge is password-protected, first remove the password using PurePDF's Encrypt PDF tool (which supports both encrypting and decrypting) or another utility. Once you have an unlocked version of all source files, you can merge them normally. After merging, you can re-apply password protection to the combined output using the Encrypt PDF tool if required.