The best open source alternative to SumatraPDF is Okular. If that doesn't suit you, our users have ranked more than 100 alternatives to SumatraPDF and loads of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to SumatraPDF are Evince, MuPDF, Stirling PDF and Koodo Reader.
Multi-platform document viewer supporting PDF, ePub, comics, images, and Markdown with annotation, digital signature verification, tabbed interface, sidebar navigation, text selection, text-to-speech, magnifier, search, dark mode, and plugin support.
Germany
EU
Supports viewing and editing PDF annotations, displays multiple formats such as PDF, Postscript, DjVu, comic books, TIFF, DVI, XPS, remembers per-document zoom and position, features search, table-of-contents navigation, SyncTeX integration, and printing.
United States
MuPDF offers a highly versatile PDF, XPS, and eBook interpreter, customizable as a renderer, viewer, or toolkit. Features include digital signatures, redactions, form filling, annotations, and page manipulation, ideal for mobile, eBooks, and embedded apps supporting Java, C++, and Python.
United States
Locally hosted web application offering an interactive GUI to merge, split, reorganize, convert, compress, watermark, secure, sign, flatten, repair, extract images, detect blanks, apply OCR, set permissions, and enable file processing or API integration for PDFs.
United States
Koodo Reader is a powerful ebook reader designed to provide a simple and easy-to-use reading experience.
China
Librera Reader is a highly customizable and feature-rich application for reading books in PDF, EPUB, MOBI, DjVu, FB2, TXT, RTF, AZW, AZW3, HTML, CBZ, CBR formats on Android devices.
SlovakiaEU
PDF Viewer (aka pdf.js) is a new revolutionary extension using web standard technologies that allows you to display within Mozilla Firefox almost all PDF files found on the web without a plugin.
United States
Openlib is an open source app to download and read books from shadow library (Anna’s Archive). The App Has Built In Reader to Read Books.
High-performance viewer for documents and images offering split tabs, customizable single or book layouts, portals for side-by-side sections, instant search, line highlight, annotation tools, link hints, searchable highlights, session management, and TOML config.
SpainEU
Sioyek is a PDF viewer with minimal interface optimized for reading research papers and technical books.
United States
Simple Android PDF viewer based on pdf.js and content providers. The app doesn't require any permissions.
Canada
