Convert E-books to Any Extension
Support for 18+ e-book and document file types. Secure server-side processing with automatic file cleanup.
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Supported E-book Extensions
Convert between 18 different file extensions - from modern e-readers to legacy formats
E-book Formats
Electronic Publication - universal e-book file extension based on HTML, CSS, and XML. Reflowable text adapts to any screen size. Supports fonts, images, metadata, and CSS styling. Industry standard for e-books with compatibility across Kobo, Nook, Apple Books, Google Play Books, and most e-reader apps. EPUB 3 adds multimedia, interactivity, and fixed-layout support. Essential format for digital publishing and cross-platform e-book distribution.
Portable Document Format - fixed-layout extension maintaining exact visual appearance across all devices. Preserves fonts, images, formatting, and page layout precisely. Universal compatibility with all operating systems and devices. Not ideal for reflowable e-book reading but perfect for textbooks, manuals, forms, academic papers, and any document requiring print-like fidelity. Standard for document exchange and archival since 1993.
Mobipocket - legacy e-book file type originally for Palm PDAs, later acquired by Amazon. Reflowable format supporting basic HTML formatting. Standard for older Kindle devices (pre-2011) and Kindle apps. Being phased out in favor of AZW3/KFX but still widely supported for backwards compatibility. Simpler than EPUB with fewer features but excellent Kindle compatibility. Common in older e-book libraries and legacy Kindle collections.
Kindle Format 8 (KF8) - Amazon's modern e-book format with enhanced features over MOBI. Supports embedded fonts, fixed layouts, HTML5, CSS3, and better formatting control. Standard for Kindle devices from 2011 onwards. Equivalent capabilities to EPUB with Kindle ecosystem integration. DRM-protected when purchased from Amazon. Excellent for modern Kindle e-books requiring rich formatting, complex layouts, and enhanced typography.
Document Formats
Microsoft Word Open XML Document - standard editable document format for word processing. Zipped XML structure containing text, formatting, images, and styles. Universal standard for document creation, editing, and collaboration. Perfect for manuscript editing, academic writing, and document workflows before converting to e-book formats. Native format for Microsoft Word, compatible with Google Docs, LibreOffice, and all major word processors.
Plain Text - simplest possible format containing only unformatted characters without styling, images, or metadata. Universal compatibility across all platforms, devices, and applications. Tiny file sizes. Perfect for reading on any device including vintage hardware. Ideal for project Gutenberg books, code, logs, and situations requiring maximum simplicity and portability. Foundation format that predates computers, working everywhere since 1960s.
HyperText Markup Language - web page format that forms the foundation of internet content. Text with HTML tags for structure, styling (CSS), and interactivity (JavaScript). Readable in any web browser without special software. Common for online books, documentation, and web-based reading. Can be converted to EPUB (which is HTML-based) or read directly in browsers. Standard format for web publishing and online documentation since 1991.
Rich Text Format - cross-platform document format developed by Microsoft (1987) for exchanging formatted text between applications. Supports fonts, colors, styles, and basic formatting without complex features. Excellent compatibility across word processors (Word, WordPad, LibreOffice, Google Docs). Larger than DOCX but more universal for legacy systems. Common intermediate format for document conversion and cross-platform text exchange.
Kindle Formats
Amazon Kindle Format - proprietary e-book format based on MOBI with Amazon's DRM protection. Used for purchased e-books from Kindle Store. Contains licensing information tied to Amazon account. Equivalent to MOBI in formatting capabilities but with copy protection. Standard for commercial Kindle e-books ensuring digital rights management. Cannot be freely shared or read on non-Amazon devices without DRM removal.
Kindle Format 10 - Amazon's latest e-book format (2015+) with enhanced typography, improved layout engine, and better font rendering. Supports advanced features like enhanced typesetting, page flip, and better hyphenation. Gradual rollout across newer Kindle devices and apps. Offers best reading experience on modern Kindles with features like Bookerly font and improved spacing. Future standard for Kindle e-books with superior formatting over AZW3.
Other Formats
FictionBook 2.0 - XML-based e-book format extremely popular in Russia and Eastern Europe. Open-source standard emphasizing semantic structure over formatting. Supports metadata, styles, and embedded images. Reflowable with excellent formatting control. Popular in Russian e-book libraries (Lib.ru, Flibusta) and reading apps like FBReader. Preferred format in Russian-speaking markets for fiction and literature with strong community support.
Microsoft Reader - legacy e-book format from Microsoft's discontinued e-book reader software (2000-2012). Fixed-layout format with ClearType font rendering and DRM support. Obsolete since Microsoft Reader discontinuation but encountered in archived e-book collections. Historical format from early e-book era, maintained for accessing legacy Microsoft Reader libraries and vintage e-book archives from 2000s.
Palm Database - e-book format for Palm OS handheld devices (Palm Pilot, Handspring Visor, 1996-2010). Contains Doc, eReader, or other Palm e-book formats in database structure. Standard on PDAs before smartphones. Legacy format for vintage Palm device enthusiasts and accessing archived Palm e-book libraries. Part of PDA history, maintained for retro computing and historical e-book preservation.
Comic Book Archive (ZIP) - digital comic book format containing sequential images (JPG, PNG) in ZIP archive with .cbz extension. Standard for manga, comics, and graphic novels. Maintains image quality and reading order. Compatible with comic readers (CDisplayEx, ComicRack, Perfect Viewer). Simple format (rename .zip to .cbz) making it easy to create. Essential for digital comic collections and manga reading. Also supports CBR (RAR-based) variant.
Sony Portable Reader Format - proprietary e-book format for Sony Reader devices (2006-2014). Supports reflowable text, images, and basic formatting. Compressed format with DRM capabilities. Obsolete since Sony discontinued Reader line. Limited software support for reading or creating. Convert to EPUB for modern e-readers. Historical format important only for accessing old Sony Reader content. Not recommended for new content.
RocketBook - proprietary format for Rocket eBook reader, one of the first dedicated e-readers (1998-2000). Pioneering format in e-book history but now completely obsolete. No modern software support. Extremely difficult to read on current devices. Convert to EPUB for accessibility. Historical importance as early e-book format. Relevant only for digital archiving and e-book format history. Not suitable for any modern use.
Shanda Bambook - proprietary format for Shanda Bambook e-readers popular in China. Compressed format supporting text, images, and Chinese typography. Limited to Bambook devices and related software. Minimal international usage. Convert to EPUB for broader compatibility. Regional format primarily used in Chinese market. Important for Chinese e-book collections but limited global relevance. Consider EPUB for international distribution.
Text Compression for Reader - compressed text format for Psion devices and PalmOS. Simple text-only format with compression but no formatting. Tiny file sizes perfect for limited device storage. Legacy format from PDA era. Very limited modern support. Convert to EPUB or PDF for current devices. Historical format representing early mobile reading. Only relevant for accessing vintage PDA content. Use modern formats for new content.
Complete Guide to E-book Conversion
E-book format conversion is essential for device compatibility, reading experience, and publishing workflows. Our free e-book converter provides a browser-based interface for 14+ formats. Learn everything you need to know about e-book formats, conversion best practices, and format compatibility below.
Frequently Asked Questions About E-book Conversion
What is E-book Format Conversion and Why Do I Need It?
E-book format conversion is the process of changing an e-book or document file from one format to another (e.g., EPUB to MOBI, PDF to EPUB, DOCX to AZW3). Different e-book formats have different characteristics: some are reflowable (EPUB, MOBI, AZW3), some are fixed-layout (PDF), some are proprietary (AZW, KFX), and some are open-source (EPUB, FB2). Each format is optimized for specific e-readers and use cases.
You need e-book conversion for multiple reasons: device compatibility (converting EPUB to MOBI for older Kindles), e-reader optimization (converting PDF to EPUB for better reflowable text), publishing requirements (converting DOCX manuscripts to EPUB for distribution), library management (standardizing your e-book collection), and accessibility (converting formats for better screen reader support). Our converter handles all these scenarios with 14+ format support.
How Does Browser-Based E-book Conversion Work?
Our converter provides a browser-based interface for e-book conversion:
Complete Privacy:
The conversion interface runs entirely in your browser. File selection and format choice happen locally. No automatic uploads to external servers. This ensures complete privacy for unpublished manuscripts, personal books, or copyrighted content.
Instant Interface:
No waiting to load heavy applications. The format selector appears instantly in your browser. Choose your settings and initiate conversion immediately.
Local Processing:
The interface works offline once loaded. Select files and choose formats without requiring constant internet connectivity.
Professional Tools:
Uses modern JavaScript and Web APIs for the interface. Note: Professional e-book conversion (format changes, metadata preservation, complex layouts) requires specialized tools like Calibre (ebook-convert) for optimal results.
This approach ensures maximum privacy and convenience while supporting 14 different e-book and document formats.
Which E-book Extension Should I Use?
Choosing the right file extension depends on your specific use case:
For Kindle Devices:
Use MOBI for older Kindles (pre-2011 models). AZW3 for modern Kindles (2011+, better formatting and features). KFX for newest Kindles (2015+, enhanced typography). EPUB is now supported by newer Kindles via Send to Kindle.
For Universal E-readers:
Use EPUB for maximum compatibility (Kobo, Nook, Apple Books, Google Play Books, most e-reader apps). EPUB 3 for enhanced features (audio, video, interactivity). EPUB is the industry standard for non-Kindle devices.
For Fixed-Layout Books:
Use PDF for textbooks, manuals, graphic novels, and any content requiring exact layout preservation. PDF maintains fonts, images, and positioning perfectly. Not ideal for reflowable text or small screens.
For Editing and Publishing:
Use DOCX for manuscript editing in Word. Convert DOCX to EPUB/MOBI for publishing. Keep DOCX as your master format for easy updates. HTML for web-based reading and maximum control over styling.
For Simple Text Reading:
Use TXT for plain text with no formatting. Perfect for simple notes, scripts, and basic reading. Universal compatibility but no styling, images, or formatting.
For Archival and Collections:
Use EPUB for modern e-book collections (metadata, cover images, proper structure). PDF for preserving exact layout of scanned books. FB2 if you prefer XML-based open format.
For Mobile Reading Apps:
iPhone/iPad: EPUB for Apple Books. Android: EPUB works in most apps (Google Play Books, Moon+ Reader, FBReader). Kindle app: MOBI or AZW3 or use Send to Kindle for EPUB.
Still unsure? EPUB is universally compatible and works for 95% of e-readers and reading apps.
What's the Difference Between EPUB, MOBI, and PDF?
EPUB is the modern industry standard e-book format – reflowable text, adjustable font size, works on most e-readers (except older Kindles). EPUB 3 supports multimedia, interactivity, and fixed layouts. Open standard, widely adopted, best for general e-books and novels.
MOBI/AZW3 are Amazon Kindle formats – MOBI is older (pre-2011 Kindles), AZW3 (Kindle Format 8) is modern with better features. Reflowable like EPUB but proprietary to Amazon. AZW3 supports better typography, embedded fonts, and enhanced layouts compared to MOBI.
PDF is fixed-layout document format – preserves exact appearance (fonts, images, positioning). Not reflowable so text size can't be adjusted. Best for textbooks, manuals, forms, and graphic-heavy content. Poor for novels on small screens. Universal compatibility but less e-reader-friendly.
Can I Convert Multiple E-books at Once?
YES! Our converter supports bulk/batch conversion of multiple e-book files simultaneously. Simply select multiple files at once (use Ctrl+Click or Cmd+Click, or drag-and-drop multiple files). All e-books will use your selected output format.
After conversion completes, you have download options: Download each file individually by clicking its download button, or use 'Download All as ZIP' to get all converted e-books in a single compressed archive. The ZIP option is perfect for converting book series, library collections, or multiple documents – one organized file with all e-books properly named.
Processing considerations: E-book conversion is less intensive than video but complex formats (EPUB with images, PDF) may take time. For best results with large batches or complex conversions, consider using Calibre desktop software which offers professional-grade conversion with advanced options.
How Do I Convert PDF to EPUB?
Converting PDF to EPUB is one of the most common e-book conversions. PDFs are fixed-layout (exact positioning) while EPUBs are reflowable (text adapts to screen size). This conversion works best with text-heavy PDFs created digitally. Scanned PDFs (images of pages) require OCR (Optical Character Recognition) first.
Best practices: PDFs with simple text convert well. Complex layouts (multiple columns, text boxes) may lose formatting. Images, tables, and charts usually preserve but positioning may change. For best results, convert PDFs that were originally created from documents (Word, InDesign) rather than scanned books.
Limitations: PDF to EPUB conversion is imperfect due to fundamental format differences (fixed vs. reflowable). Expect to manually adjust formatting for optimal EPUB quality. For professional publishing, use source documents (DOCX, HTML) rather than PDF when possible. Calibre provides advanced PDF conversion options with better control.
Can I Convert DOCX to EPUB/MOBI?
YES! Converting Word documents (DOCX) to e-book formats is ideal for self-publishing. DOCX is structured document format that converts well to reflowable EPUB/MOBI. This is the recommended workflow for authors: write in Word, convert to e-book formats for distribution.
Preparation tips: Use Word styles (Heading 1, Heading 2, Normal) for proper chapter structure. Avoid manual formatting (spacebar indents, multiple enters). Insert images properly (not text-wrapped). Use page breaks for chapters. Add metadata (title, author) in Word properties. Proper DOCX structure produces better EPUB/MOBI quality.
Publishing workflow: Keep DOCX as master file. Convert to EPUB for most platforms (Apple Books, Kobo, Nook, Google Play). Convert to MOBI/AZW3 for Kindle Direct Publishing. Make edits in DOCX then re-convert rather than editing e-book files directly. This maintains consistency across formats.
How Do I Maintain Formatting During Conversion?
Follow these best practices to preserve formatting:
Use Source Documents:
Always convert from source format (DOCX, HTML) rather than intermediate formats. Converting DOCX→EPUB is better than DOCX→PDF→EPUB. Each conversion step can lose formatting details.
Proper Document Structure:
Use semantic markup (headings, paragraphs, lists) instead of manual formatting. This ensures better conversion to e-book formats. Avoid complex layouts that don't translate well to reflowable e-books.
Image Handling:
Include high-quality images in source. Images convert but may be resized for e-readers. Use standard formats (JPEG, PNG). Avoid excessive image size as it bloats e-book file size.
Metadata Preservation:
Add metadata in source document (title, author, publisher, description). Professional tools like Calibre preserve and enhance metadata during conversion. Metadata improves library organization.
Test on Target Devices:
After conversion, test e-books on actual devices (Kindle, iPad, Android app). Different e-readers render formatting slightly differently. Adjust source and re-convert if needed.
Remember: Start with well-formatted source documents, use semantic structure, test on target devices, keep source files for future updates.
Is E-book Conversion Really Free?
YES, our converter interface is 100% free! Use the format selector and conversion interface with no restrictions: No account required, no registration, no login, no credit card, no hidden fees, no watermarks, no file size limits, no daily conversion limits, and no premium tiers. The interface and format selection tools are free for everyone, always.
Important note: While the browser interface is free and provides the conversion workflow, professional e-book conversion (complex layouts, metadata preservation, advanced formatting) benefits from specialized tools like Calibre (free, open-source) which provides comprehensive e-book management and conversion with advanced options. Our interface helps you organize and initiate conversions.
You can use converted e-books for any purpose: personal reading, library organization, publishing, selling on platforms, distribution, or anything else (respecting copyright laws). No attribution required. The converted e-books are 100% yours with no strings attached.
What Are the Supported E-book Extensions?
We support 18 e-book and document file extensions across 5 categories:
E-book Extensions (4):
EPUB, PDF, MOBI, AZW3 – All standard file types for e-readers, tablets, and reading apps.
Document Extensions (4):
DOCX, TXT, HTML, RTF – Editable and web-based text formats for writing and publishing.
Kindle Extensions (2):
AZW, KFX – Amazon proprietary file types for various Kindle device generations.
Other Extensions (4):
FB2, LIT, PDB, CBZ – Specialized and legacy e-book file types for specific readers and use cases.
How Fast is the E-book Conversion Process?
E-book conversion speed depends on several factors: file size (larger e-books take more time), format complexity (PDF with images is slower than TXT), number of images (more images = longer processing), and your device's processing power (newer computers are faster).
Typical speeds with modern hardware: Simple conversions (TXT→EPUB, DOCX→MOBI): 1-5 seconds. Image-heavy e-books (PDF→EPUB with photos): 10-30 seconds. Complex layouts (PDF with tables→EPUB): 30-60 seconds. Batch conversion: 10 e-books in 1-5 minutes depending on complexity.
Optimization tips: Convert simpler formats for faster processing. For professional publishing with complex layouts, use Calibre desktop software which offers optimized conversion algorithms. Batch convert overnight for large library collections. Format conversion (EPUB→MOBI) is faster than layout conversion (PDF→EPUB).
Can I Convert E-books on Mobile Devices?
YES! Our converter interface works on smartphones and tablets (iOS, Android, all mobile browsers). The interface is responsive and touch-optimized. E-book conversion is less resource-intensive than video, so mobile devices handle it reasonably well.
Mobile considerations: Simple e-book conversions work fine on mobile. Complex PDFs or large files (>50MB) may be slower. Memory limitations on older phones may restrict very large e-books. Newer phones handle most e-book conversions smoothly.
Mobile workflow: Perfect for converting e-books before reading on your device. Download e-book → convert to compatible format → open in reading app. Convert purchases to compatible formats (EPUB→MOBI for Kindle app). Ideal for quick on-the-go conversions.
What Happens to E-book Metadata and Cover Images?
E-book metadata includes information like title, author, publisher, publication date, ISBN, description, series, language, and cover image. Metadata is crucial for library organization and discoverability. Our converter attempts to preserve basic metadata during format conversion.
Metadata handling: Title, author, and basic info usually preserved when both formats support it. Cover images typically preserved for EPUB, MOBI, AZW3 conversions. Advanced metadata (series, tags, ratings) depends on format capabilities. For comprehensive metadata management, use Calibre which excels at metadata editing.
Best practices: Add metadata before conversion for best results. Use Calibre to enhance metadata after conversion. Keep cover images as separate files for easy replacement. Proper metadata improves e-book browsing in libraries and e-reader devices.
How Do I Handle DRM-Protected E-books?
DRM (Digital Rights Management) is copy protection applied to purchased e-books from major platforms (Amazon, Apple, Kobo). DRM-protected e-books cannot be converted directly. Our converter, like all legitimate tools, does not remove or bypass DRM protection.
DRM-free alternatives: Purchase from DRM-free stores (Tor Books, Smashwords, direct from authors). Many publishers now offer DRM-free options. For books you own, contact publisher about DRM-free versions. Use platform-specific apps to read DRM books (Kindle app for Amazon books, Apple Books for Apple purchases).
Legal considerations: Removing DRM may violate terms of service and copyright law depending on your jurisdiction. Only convert e-books you own rights to or are DRM-free. For personal library, use platform apps rather than conversion. Authors and publishers deserve compensation for their work.
What's the Best Extension for Self-Publishing?
For Amazon Kindle (KDP): Upload MOBI or EPUB. KDP accepts both and converts automatically. AZW3 is generated by KDP for modern Kindles. For best quality, upload clean EPUB or high-quality DOCX. Amazon's conversion is generally good but review preview carefully.
For Other Platforms: Use EPUB 2 or EPUB 3 for universal compatibility. Apple Books, Kobo, Nook, Google Play Books all accept EPUB. Draft2Digital and Smashwords accept DOCX and convert to multiple file types. EPUB is the industry standard for non-Kindle platforms.
Professional workflow: Write in DOCX using proper styles. Convert to EPUB for most platforms. Upload EPUB to KDP (Amazon converts automatically). Use Calibre to validate EPUB quality. Test on multiple devices before publishing. Keep DOCX as master for updates. Consider professional formatting services for complex layouts.