Start with this check.
On Android, start with Files by Google if installed, or consider MJ PDF for a dedicated reader. On Windows, SumatraPDF offers local reading without ads or a subscription. Use the linked official store or publisher page and test a document before making the reader your default.
No ads does not mean identical data policies. Review each app’s permissions and listing. Keep a copy before annotating important documents and distinguish a drawn signature from a certificate-based digital signature.
Which situation matches yours?
Let’s go step by step.
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Try Files by Google on Android
Check that the app is Files by Google from Google LLC. Its listing declares no ads. Open a PDF through Recents or search within Files. If already installed, try it before adding another reader.
You do not need to run cleanup recommendations to read a file. Review its privacy listing too: no ads does not mean no data collection.
Check the functions you need
In the Files PDF viewer, test zoom, text search and printing if needed. Annotation is also documented. Save a copy when making changes and reopen it to verify. Check compatibility before relying on original-text editing or a specialised form.
Reading, annotating and editing original content are different functions. Opening a PDF does not guarantee every form or signature works.
Consider MJ PDF for dedicated reading
Mudlej’s project describes a free, open-source reader without ads or tracking. Features include search, reading modes, annotation and forms. Use distribution links from its official page, reached through the linked project documentation, and avoid similarly named apps.
Review permissions: it documents file access and Internet use for links or approved reports. Opening a local PDF does not require uploading it to a conversion website.
On Windows, install or open SumatraPDF
Go to sumatrapdfreader.org, follow Download and choose the appropriate Windows build; a portable version is available. The project declares no ads, bundled programs or subscription. Open your file and check search, zoom and printing as needed.
This is a Windows reading option. Do not assume it replaces every editing or signing feature of a professional editor.
Change the reader that opens automatically
On Android, try Open with from the file. If offered, choose the reader and Just once to test, then Always if suitable. If another app handles every opening, inspect its Settings entry and clear default preferences. On Pixel: Apps → app → Open by default → Clear default preferences; other brands use different labels.
Reopen a downloaded PDF to verify. Another app’s embedded viewer may remain inside that app; downloading the file lets you test your chosen reader.
Associate .pdf on Windows and remove the old reader
In Windows 11, open Settings → Apps → Default apps, search for .pdf and choose your reader. Before uninstalling the previous app, save documents or annotations held only within it. If Android still shows ads or an altered home screen, follow the related advertising and launcher guides.
Test a local file afterwards. Do not rely on uninstalling to cancel a subscription; check where it was purchased.
When to stop and ask for help
If only one PDF fails, test a known document before adding more readers. For official forms, certificates or protected files, consult the issuer’s requirements. Do not upload private documents to unknown sites merely because an app suggests conversion.
Does a step differ from what you see? →Common questions
Which should I try first?
Files by Google for everyday Android reading, MJ PDF for a dedicated reader, or SumatraPDF on Windows. Choose by required features.
Are these short free trials?
These are free-reading options, not temporary promotions. Check the official version’s current terms.
Does a PDF reader need to change my launcher?
Changing the home screen is unnecessary for reading a document.
Can I read offline?
Already downloaded documents can be read locally. Links and downloading require connectivity.
Does no ads mean no data collected?
No. Review each app’s policy and permissions separately.
Sources and review
Project owner: Eudald Ferrer Ibáñez. Report a correction.
This guide uses official documentation and our own troubleshooting sequence. Menus may change between versions. Documentation reviewed on September 28, 2026; practical device testing is still pending.
- Google: Files by Google and no ads
- Google: open and annotate PDFs in Files
- MJ PDF: author documentation and privacy
- SumatraPDF: free reader without ads
- Google: change default apps on Pixel
- Microsoft: change default apps
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