Convert CHM to EPUB
CHM was designed to make a linked help system available offline, while EPUB was designed to let a reader resize and repaginate a publication. Moving between them is a useful way to read an old technical manual on a phone or ebook application, but the operation is a reconstruction rather than a simple repackaging. A CHM can contain hundreds of HTML topics, a contents hierarchy, CSS, images, scripts, and viewer metadata. EPUB can hold chapters and resources too, yet it expects a publication spine and ebook navigation. This page converts readable material into that model while being candid about missing styles, incomplete assets, and the fact that no DRM is removed or bypassed.
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Add to Chrome — freeDrop your CHM file here, or click to browse
Up to 50 MB. Deleted automatically after 30 minutes.
What it does
- Builds a reflowable EPUB from readable CHM topics
- Makes legacy manuals easier to open in ebook readers
- Carries ordinary HTML text and supported images where possible
- No watermark and no sign-up
How to use CHM to EPUB
- 1
Add an accessible CHM
Select a file you authored, own, or are permitted to transform. This service does not remove DRM, decrypt account-bound content, or bypass a publisher's protection.
- 2
Extract the HTML topics
The server uses extract_chmLib to extract HTML from the CHM. It then produces the selected EPUB from that extracted HTML, building a reflowable book package instead of preserving the original help viewer window.
- 3
Read and check the EPUB
Open the result in the intended app and inspect the reading order, contents menu, title metadata, images, links, code, and tables. Keep the CHM until those checks are complete.
How it works
The server first treats the input as a compiled help archive. extract_chmLib extracts
HTML from the CHM into a temporary directory, and then the selected EPUB output is
produced from the extracted HTML. The resulting file is a real ebook package with
content documents, a manifest, a spine, navigation, metadata, and any resources the
conversion path can connect. It is not a renamed CHM and it does not retain the help
viewer as an embedded application.
Reflow is the main change. An ebook reader decides line breaks from the screen width, font size, margins, and orientation. A help topic that looked tidy in a desktop window may therefore become several screens, while a wide code sample may need horizontal inspection or a simpler layout. That behavior is normal for EPUB and is often the reason to choose it for a portable manual.
Structure versus appearance
The best candidates have semantic headings, paragraphs, lists, and images with sensible relative links. Those elements can be represented in EPUB content documents. A CHM built around frames, script-generated navigation, hover menus, or absolute coordinates is more dependent on the old viewer. The words may still arrive, but the route through them and the visual hierarchy can change.
CSS has limits here. Basic styles may be translated, but there is no promise of exact fonts, background images, browser scripting, custom widgets, or every local asset. A single ebook file can be valid while still showing an unstyled table or a missing diagram. Keep the original CHM and compare an image-heavy topic, a code sample, and a deeply nested section before treating the EPUB as a finished edition.
Reader checks that matter
Open the table of contents, jump to the first and last topic, change the type size, and search for a distinctive phrase. Verify title, author, and language metadata if the manual will enter a library. On a phone, check diagrams and tables in portrait and landscape. If a resource is essential but missing, the original CHM's extracted asset tree may need local editorial repair; this online conversion does not promise a complete website or a DRM workaround.
Examples
A field service manual for a tablet reader
The EPUB lets a technician enlarge text and read the manual without the legacy viewer. Diagrams remain valuable only after a check on the small screen, because fixed-width tables and labels can wrap differently inside an ebook reader.
A reference library migration
The new package is easier to index with an ebook library and works across more reading apps. It is not a full website clone: CSS rules, scripts, topic links, and image paths deserve a chapter-by-chapter review before distribution.
Frequently asked questions
Does CHM to EPUB make every help topic a chapter?
Not always. The converter extracts HTML and asks the ebook output path to infer a publication structure, but a CHM contents tree, topic filenames, and EPUB spine are different systems. Clear headings and ordinary links tend to help, while frames, generated menus, and unusual topic layouts may produce an imperfect contents menu. Open the EPUB's navigation and check the order before sharing it as a complete book.
Are CSS and images included in the EPUB?
Some ordinary styles and image resources can be carried into the ebook, but the result does not promise every CSS rule, font, background, script, or relative asset. CHM topics may rely on a local viewer or paths that do not translate cleanly into an EPUB package. Missing styling can leave readable text, while missing diagrams can change the meaning, so inspect technical sections rather than trusting the file size.
Can this service bypass DRM on a CHM?
No. It does not remove DRM, decrypt protected content, defeat a vendor's account controls, or turn an unreadable package into an authorized ebook. The extraction tool needs access to the source topics. Use an unprotected file you created or own, or obtain permission from the rights holder. Renaming a protected file does not change its access rights.