On most Windows PCs, PDFs open in Microsoft Edge by default. Over the past year, Microsoft has been moving Edge's built-in viewer from its own legacy engine to one powered by Adobe's PDF technology, under a partnership announced in 2023 on the Microsoft Edge Insider blog. According to Microsoft 365 message center notices, the new viewer became the default from October 2025, and as of autumn 2026 the legacy engine is scheduled for removal in a later Edge version. Exact timing can shift, so check your organisation's admin notices if you manage Edge at work.
Here is what the change means in practice.
What should improve
Microsoft and Adobe have said the new engine brings:
- More accurate rendering of colours, fonts and graphics.
- Better performance on large files.
- Improved text selection and read-aloud, which helps accessibility.
The viewer remains free and built into Edge. It is separate from Adobe Acrobat, the paid product.
What to check after the switch
Any change of rendering engine can surface small differences:
- Printing: page scaling and margins may differ. Print a test page of important documents. If pages come out blank or cut off, see PDF printing blank fixes.
- Forms: fillable forms should work, but check that entries save. See fillable PDF form not saving.
- Signatures: if you rely on validating digital signatures, check how the new viewer displays signature status. See how to verify a digital signature in a PDF.
- Organisation policies: administrators who configured the legacy viewer through policy should review Microsoft's notices before the old engine is removed.
If you prefer a different PDF app
Edge is the default, not a requirement. You can change which app opens PDFs in Settings → Apps → Default apps. See PDF opens in browser instead of app.
Browser viewers and privacy
Viewing a PDF in Edge's built-in viewer happens on your PC. Some optional features in modern viewers and browsers, such as AI summaries or cloud sync, may send content elsewhere, depending on your settings. If you handle sensitive documents, check those settings. Our guide to AI assistants in PDF readers and privacy settings covers what to look for.
Where a viewer is not enough
A viewer is for reading, light annotation and printing. For merging, splitting, compressing, signing or reorganising pages, you need an editor. Docento.app does these in the browser, processing files on your device. See best free Adobe Acrobat alternatives for a wider comparison.
Takeaway
Edge's PDF viewer now runs on an Adobe-powered engine, with the legacy engine on its way out. For most people that means better rendering and accessibility. Test printing, forms and signature display for any document you depend on, and change the default PDF app if Edge is not what you want.
