Sumatra PDF is a Windows document reader for PDFs, ebooks, help files, scanned publications, and comic archives. It opens PDF, EPUB, MOBI, CHM, XPS, DjVu, CBZ, and CBR files in the same tabbed window. Sumatra PDF is mainly a reader: it navigates, searches, prints, presents, and marks documents, but it is not a page-layout editor for rewriting paragraphs or rearranging a publication.
Different reading engines
A PDF keeps its fixed page geometry, so zooming changes the view without reflowing the page. EPUB, MOBI, and FB2 books use an ebook view where the font, size, margins, and line spacing can change. Sumatra PDF can store those choices for one book or apply them to all ebooks. Comic archives open as ordered pages and can use right-to-left reading for manga.
The format name does not remove the source file’s restrictions. Kindle-family support covers MOBI and unencrypted AZW, AZW3, and PRC files. A book protected by encryption will not open merely because its extension appears in the supported list. Likewise, a PDF made only from photographed pages has no searchable text unless the file already contains a text layer.
Tabs and landmarks
Sumatra PDF keeps several documents in tabs and remembers recently opened files. The table-of-contents panel follows bookmarks embedded by the document creator. Personal favorites mark pages independently, so a long manual can have a local return point even when its published bookmark tree is sparse.
The command palette gathers actions, open tabs, history, table-of-contents entries, and favorites behind one search field. Keyboard shortcuts cover page movement, zoom, presentation mode, tab switching, and selection. These controls reward regular use, but single-letter shortcuts can be surprising when focus sits on the document instead of a text field.
Annotations need saving
Sumatra PDF can add highlights, underlines, strikeouts, squiggly marks, text notes, stamps, and image annotations to a PDF. Selecting text and pressing the annotation shortcut creates a mark quickly. The annotation editor changes color, text, opacity, and other properties, and an image can act as a visible signature stamp.
Edits remain pending until they are saved. Closing a document with pending marks opens a choice to save, write a new PDF, or discard. Discard removes the unsaved work. Saving to the existing PDF overwrites that file, while saving a new copy preserves the original. Annotation editing has no general undo command, so deleting or moving the wrong mark may require manual correction rather than a simple reversal.
Most standard annotations made by other PDF readers display correctly. Proprietary annotation types can appear only as an icon, and Sumatra PDF does not implement every annotation operation found in dedicated PDF editors. An image signature is also different from a certificate-backed digital signature; one places visible artwork, while the other records cryptographic signing information.
Search and print
Text search moves through the current document, and search results depend on text that the file exposes. A scanned page without optical character recognition behaves like an image. Sumatra PDF can display and print it, but typing a word will not discover letters that exist only as pixels.
Printing uses the document’s rendered pages and the selected printer settings. Presentation mode removes ordinary window furniture for full-screen reading. Read aloud uses installed speech support for accessible text, but it cannot infer a reliable reading order from every complex layout. Multi-column pages, decorative text, or malformed tags can produce a spoken sequence that differs from the visual page.
