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SUN to FB2 Converter

Turn SUN into FB2 ebooks online for free

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Data Protection

Your uploaded SUN data is deleted right after conversion, and the FB2 output is removed from servers within 24 hours — keeping your content private.

Server-Side Processing

Conversion happens entirely on Convertio's servers. Your device stays responsive while SUN data is transformed into FB2 in the cloud.

Zero Install

Run the entire SUN to FB2 conversion in your web browser. No downloads, plugins, or system requirements beyond an internet connection.

How to convert SUN to FB2

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose fb2 or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your fb2 file right afterwards

About formats

SUN is a raster image format associated with Sun Microsystems workstations, encompassing both the Sun Raster format (.ras) and the Sun Icon format used for window system icons and cursors on SunOS and Solaris systems. Sun Raster files, identifiable by their 0x59a66a95 magic number, store bitmap images in 1-bit monochrome, 8-bit indexed color, 24-bit BGR, or 32-bit XBGR modes, with optional run-length encoding compression and a 32-byte header. The Sun Icon subset is a simpler text-based format used for small monochrome bitmaps — window icons, cursor images, and toolbar graphics — stored as C-language data arrays that could be directly compiled into X Window and SunView applications. These icon files begin with a comment block specifying width, height, and optionally hot spot coordinates (for cursor images), followed by hexadecimal pixel values in a format readable by both the C compiler and the iconedit tool. Sun workstations running SunOS and later Solaris were foundational platforms for Unix computing, networking, and the early internet, and the SUN image formats were integral to their graphical environments. One advantage is the format's dual text/binary nature: Sun Icons are valid C source code that can be #included directly into applications, a practical approach to resource embedding that predates modern asset management systems. The Sun Raster variant's simplicity provides another strength — the 32-byte header and straightforward encoding make it one of the easiest binary image formats to parse. SUN format files are supported by ImageMagick, GIMP, XnView, and Unix image viewing tools.
Developer: Sun Microsystems
Initial release: 1982
FB2 (FictionBook) is an XML-based ebook format created by Dmitry Gribov in 2004, designed to provide a clean semantic description of a book's content independent of its visual presentation. Unlike page-layout formats, FB2 encodes structure — title, authors, chapters, annotations, genres, epigraphs, poems, footnotes, and binary attachments (typically cover images) — within a single well-formed XML document. This structural approach means reading applications have full control over rendering, allowing the same file to adapt perfectly to a small phone screen or a large e-ink reader. FB2 became enormously popular in Russia and Eastern Europe, serving as the dominant format on major Russian digital libraries and ebook distribution platforms. One significant advantage is metadata richness: the format's schema mandates detailed bibliographic information including author, translator, series position, publication date, and genre classification, making library management and discovery straightforward. The plain-text XML foundation is another strength — FB2 files are human-readable, easy to validate, and simple to transform using standard XML tools like XSLT. The format specification is freely available on GitHub, and a wide ecosystem of readers, editors, and converters supports it across all major platforms, from desktop applications like Calibre to dedicated e-readers with native FB2 rendering.
Developer: Dmitry Gribov
Initial release: 2004

Frequently Asked Questions

Why convert SUN to FB2?

The SUN format is nearly extinct in current software — converting to FB2 rescues the image data for use in today's applications.

What programs open FB2 files?

FB2 files can be opened in FBReader, Calibre, CoolReader, and many e-reader apps on Android and desktop.

How does Convertio protect my uploaded data?

Your SUN data is encrypted during transfer and deleted after processing. Converted FB2 outputs are purged from servers within 24 hours.

Why choose FB2 format?

FB2 offers structured ebook, XML-based, popular in Russia/CIS. Converting SUN content into FB2 makes it ready for e-readers and digital distribution.

Is SUN to FB2 conversion free?

Standard conversions are free on Convertio. Premium plans unlock larger uploads, faster processing, and higher-volume batch conversions.