SumatraPDF vs Mozilla PDF.js

SumatraPDF7.1Visit Mozilla PDF.js6.9Visit

Higher score SumatraPDF #6 in PDF Readers 7.1/10 Free plan Free plan✓ 4 of 4 features Visit SumatraPDF

vs

Mozilla PDF.js #7 in PDF Readers 6.9/10 Free plan Free plan✓ 2 of 4 features Visit Mozilla PDF.js

• SumatraPDF fits best

  Portable Windows reading with signatures

• Mozilla PDF.js fits best

  Web and application developers

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Side by side

Feature	SumatraPDF 7.1/10 Visit ↗	Mozilla PDF.js 6.9/10 Visit ↗
At a glance
Editor score	7.1	6.9
Ranking	#6 in PDF Readers	#7 in PDF Readers
Best for	Portable Windows reading with signatures	Web and application developers
Pricing model	Free	Free
Starting price	Not published	Not published
Free plan	✓	✓
Free trial	—	—
Deployment	Desktop	Self-hosted
Platforms	Windows	Web
Support	Docs, Community	Community, Docs
Built for	Solo, Small business, Mid-market	Solo, Small business, Mid-market, Enterprise
Features SumatraPDF 4/4 · Mozilla PDF.js 2/4
Annotation tools	✓	✓
Form filling	✓	✓
Offline access	✓ (best)	Not published
Text-to-speech	✓ (best)	Not published
Specs
OCR support	Not published	None
Platform support	Desktop	Web
Our review
Pros	Opens PDFs, ebooks, comics, images, and several document formats Supports annotations, digital signatures, and Windows text-to-speech Portable deployment and command-line PDF operations support local workflows	Open-source PDF parsing, rendering, search, and browser viewing Annotation editing includes highlights, free text, ink, stamps, and signatures Supports npm, CDNs, APIs, self-hosting, and Firefox and Chrome extensions
Cons	Windows-only, with no macOS, Linux, web, or mobile versions Cannot fill PDF forms, despite supporting form-field highlighting Scanned pages require OCR elsewhere	Requires developer integration rather than serving as a conventional end-user app Its focus is PDF viewing, parsing, forms, and annotations Interactive scripting is centered on PDF form calculations and actions
Our verdict	SumatraPDF is a free, open-source desktop reader for Windows. It is aimed at people who want to read PDFs and a broad set of other local formats, including EPUB, MOBI, CBZ, DjVu, XPS, CHM, and image files. Text search, document navigation,… Read the review →	Mozilla PDF.js is an open-source JavaScript library and browser-based viewer for parsing and rendering Portable Document Format files. It is aimed at web and application developers who need to embed PDF capabilities in web applications or… Read the review →

Strengths and trade-offs

• SumatraPDF — where it wins

  • Opens PDFs, ebooks, comics, images, and several document formats
  • Supports annotations, digital signatures, and Windows text-to-speech
  • Portable deployment and command-line PDF operations support local workflows

  Where it doesn't

  • Windows-only, with no macOS, Linux, web, or mobile versions
  • Cannot fill PDF forms, despite supporting form-field highlighting
  • Scanned pages require OCR elsewhere

• Mozilla PDF.js — where it wins

  • Open-source PDF parsing, rendering, search, and browser viewing
  • Annotation editing includes highlights, free text, ink, stamps, and signatures
  • Supports npm, CDNs, APIs, self-hosting, and Firefox and Chrome extensions

  Where it doesn't

  • Requires developer integration rather than serving as a conventional end-user app
  • Its focus is PDF viewing, parsing, forms, and annotations
  • Interactive scripting is centered on PDF form calculations and actions

• SumatraPDF7.1/10 · Free plan

  A portable Windows reader with broad format support, annotations, signatures, and command-line tools.

  Visit SumatraPDFFull verdict →
• Mozilla PDF.js6.9/10 · Free plan

  A developer-focused PDF viewer and rendering platform for web applications.

  Visit Mozilla PDF.jsFull verdict →