What the measured run showed
These figures describe the controlled fixture documented for this guide. They are evidence for the tested case, not a universal performance guarantee.
The controlled merge fixture
The first source PDF contained one URI link, one annotation, a text form widget named netrodoc_test_field with a known value, and a bookmark pointing to its first page. The second source contained another URI link, another annotation, and a bookmark.
The two files were merged in a fixed order through the same PyMuPDF-based merge implementation used by NetroDoc. We then reopened the output and inspected page count, links, annotations, widgets, field value, and table of contents rather than checking only that the merged PDF opened.
- The merged document contained exactly two pages in the requested order.
- Both source URI links were present in the output.
- Both source annotations were present in the output.
- The form widget remained present with the value FORM VALUE 20260909.
- Both bookmarks remained present and the second bookmark was moved to page 2.
What the implementation asks PyMuPDF to carry forward
NetroDoc calls PyMuPDF's insert_pdf with links, annotations, and widgets enabled. It also reads source bookmarks and rebuilds them with page offsets after each source document is inserted.
That implementation detail explains why our fixture retained those structures, but it is still not a universal guarantee. PDFs created by different software can contain unusual annotation types, JavaScript actions, embedded files, appearance streams, or malformed objects that were not represented in this fixture.
Digital signatures are a separate risk
We did not include a digitally signed PDF in this evidence run, so NetroDoc does not claim that a digital signature will remain valid after merging. A merge rewrites document structure and page relationships, which is exactly the kind of change that can matter to signature validation.
If signature validity is important, keep the original signed document and verify the merged output with the signing or validation software you rely on. Do not treat the absence of a visible warning as proof that a signature is still cryptographically valid.
- Visible signature artwork is not the same as a valid digital signature.
- Our current merge evidence does not cover certificate validation or signed revision integrity.
- Preserve the original signed PDF whenever legal or audit value matters.
Bookmarks and page order
Bookmarks are page references, so simply concatenating page objects is not enough. In our test the first bookmark still pointed to page 1 and the second bookmark was shifted from page 1 of its source file to page 2 of the merged output.
That result demonstrates the intended offset logic on a simple two-file fixture. Deeply nested outlines, unusual destination types, or broken source bookmarks were not part of this run and should be checked manually when they matter.
Practical checks after a merge
After merging, check more than the page thumbnails. Open important links, click form fields, inspect comments or annotations, and expand the bookmark panel. If the source files were interactive, the output should be reviewed as an interactive PDF rather than as a stack of images.
NetroDoc currently accepts up to 20 files per merge request and up to 2,000 total pages in the tested configuration. Staying within those limits does not eliminate the need to review complex interactive documents.
- Confirm page order and total page count.
- Test important external and internal links.
- Check form values and editable fields.
- Review annotations and bookmarks.
- Validate digital signatures separately when they matter.
Limits of this evidence
This evidence covers two controlled one-page source PDFs with specific links, annotations, one text widget, and simple bookmarks. It does not benchmark every PDF feature or every producer application.
The useful conclusion is narrow: these structures survived in the tested fixture and the implementation explicitly requests their preservation. Digital signatures remain outside the measured scope.
Temporary processing and privacy
Merge PDF uses temporary request processing storage. The evidence wave focused on output structure and the separate application lifecycle tests verified cleanup behaviour for temporary conversion paths; it did not test every external infrastructure failure mode.
Read the Privacy Policy →Troubleshooting
A link is missing after merge
Check whether the source link is a standard PDF link or a more unusual action. Our fixture covered ordinary URI links, not every action type.
A form looks different
Interactive fields can depend on appearance streams and viewer behaviour. Check the field value and editability in the PDF viewer you actually use.
A signed PDF was merged
Do not assume the digital signature is still valid. Digital signatures were not tested in this evidence wave; validate the result separately and keep the original signed file.
Method note
NetroDoc publishes measured claims only after a controlled run completes successfully. Untested cases are kept out of the conclusion. The evidence run for this publication wave used the same production runtime components while operating on an isolated candidate and temporary server paths.