Sumatra PDF is a reader rather than a PDF editing tool, so it cannot change PDF text or pages, fill complex forms, or sign documents. Its annotations are limited to highlights and simple notes, making it less suited to workflows that require document editing or form handling.
For reading, the program focuses on quick opening and page rendering, including on older PCs. Its minimal window and keyboard shortcuts for navigation, zoom, and view modes keep common reading tasks direct, without requiring a more elaborate interface.
That lightweight approach extends across document and book formats: Sumatra PDF can open PDF, EPUB, MOBI, CBZ, CBR, DjVu, XPS, and CHM files, as well as common image formats. This makes it practical for switching between documents, e-books, and comic archives in one reader.
Reading and navigation
Keyboard shortcuts provide a way to move through a document, change its zoom, and switch viewing modes without relying on menus for every action. The small, clean interface supports a focused reading routine, while fast startup and rendering help when opening files repeatedly.
PDF annotation is available for basic tasks. Readers can highlight passages and add simple notes, which can be useful for marking material to revisit. These tools do not extend to editing the underlying text or pages, so annotations should be understood as reading aids rather than document revision features.
Portable use and setup
A portable version can run from a folder or USB stick without installation. This provides a way to keep the reader alongside a collection of files or use it from removable storage. An installer is also available, and it can set Sumatra PDF as the default PDF reader.
The installer and portable builds are offered in 64-bit and 32-bit versions. Sumatra PDF is designed for Windows and supports Windows 10 and Windows 11; it is not a cross-platform reader.
License and best-fit tasks
Developed by Krzysztof Kowalczyk, Sumatra PDF is open source under the GNU GPL v3 and is free for all uses. Its scope is clearest when the task is to open and read supported files, use basic PDF markings, or carry a portable reader between locations.
For someone primarily reading PDFs, e-books, or comics, the format coverage and keyboard-oriented controls can reduce friction between opening a file and getting to its content. Readers who need text changes, page editing, complex form completion, or document signatures will need capabilities beyond those provided here.