A revision tool for CAD drawing PDFs

When your CAD export reaches Rev D, knowing exactly which lines, dimensions and annotations moved between revisions decides whether the next sub-contractor builds it right or builds it wrong. PDFverifier produces that diff automatically.

If you've ever held two PDF prints up to a window to find what your colleague changed, you already know why this exists. CAD drawings are dense — a single sheet of a structural drawing can contain hundreds of dimensions, hatched regions, callouts and rebar markings. Doing the comparison manually is slow, and missing a change is expensive.

Designed for the CAD workflow — PDFverifier doesn't try to be a generic document differ. It's tuned for the way engineers actually work: drawings exported from CAD tools, compared in pixel-perfect detail, reviewed visually with the option to comment per change.

What it works on

Source CAD tool doesn't matter — PDFverifier compares the rendered PDF output, so anything that produces a PDF works:

Revit sheets exported as PDF — including viewports with annotations
AutoCAD drawings exported via DWG-to-PDF or "Plot to PDF"
SolidWorks drawing sheets (slddrw → PDF)
ArchiCAD, Vectorworks, MicroStation exports
Tekla Structures drawings
Scanned hand-drawn or legacy archive drawings (use lower sensitivity)

The five-minute workflow

Export both revisions to PDF from your CAD tool. If your toolchain produces ZIP packages with multiple sheets, those work too — PDFverifier matches sheets by filename.
Drop both into the upload area on the home page. Old version on the left, new version on the right.
Hit Analyse. A typical A1 drawing takes 15-45 seconds depending on density. Multi-sheet ZIPs process in parallel.
Review changes in the viewer. Every detected addition appears as a green box, deletions in blue. Click into each to inspect, dismiss false positives, or add a comment.
Export the annotated PDF. The result is a single PDF showing the new revision with every accepted change highlighted, ready to send to the contractor or stamp into your QA system.

Tuning sensitivity for CAD output

CAD-generated PDFs are clean — every pixel is deliberate. That's both a blessing (no scan noise) and a curse (the tool will flag every tiny change including raster-rendering artefacts from different export settings).

Practical recommendations:

Same export settings, same source tool, same paper size: use sensitivity High. Picks up every intentional change without false positives.
Different paper sizes or scales: re-export both to identical settings before comparison — sensitivity tuning won't fix size mismatches.
Comparing a CAD-export against a scanned old drawing: use Low or Medium sensitivity to ignore scan noise. Real changes will still surface.
Coloured drawings: PDFverifier compares in greyscale by default, so a colour swap on the same line won't trigger a false change. Useful when offices renew their drawing template.

What it actually catches

Moved geometry

A column moved 250 mm. A wall thickness changed from 200 to 250. A dimension line shifted.

Added or removed elements

A new bracing member. A removed door. A clouded revision area with new content inside.

Annotation changes

Modified text labels, updated dimensions, edited callouts, changed revision blocks.

Hatching & line weight

A section changed from hatched to solid. A line went from 0.18 mm to 0.35 mm.

Common questions from CAD users

Will it work on multi-sheet drawing sets?

Yes — upload ZIP files containing the full sheet set on each side. PDFverifier matches sheets between revisions by filename. A 40-sheet set typically processes in under 5 minutes.

Do I need a paid plan for CAD comparison?

No, you can use the free preview to test it on real drawings. Paid plans unlock annotated PDF export and batch processing, which is what most engineering teams actually need.

Can it detect rotation or scale changes between revisions?

It detects them as differences — but as "everything changed". If you suspect a rotation/scale shift, re-export with matching settings. PDFverifier is built for changes within a stable viewport.

How does it handle viewport-rendered annotations from Revit?

Viewport annotations are part of the PDF rendering, so they're compared like everything else. Tag visibility changes between revisions (e.g. a tag turned off in a view) show up as a deletion.

What's the file size limit?

100 MB per upload. That's plenty for typical engineering drawings — even a dense A0 sheet exports to about 10-30 MB.

Is my drawing data private?

All uploads are encrypted in transit and stored on EU servers in Germany. Files are deleted automatically after 7 days (free) or 30 days (paid). We never share documents with third parties — see the privacy policy for details.

Try it on a real drawing revision

You can run a free comparison on your own files right now — no sign-up, no card.

Open PDFverifier →