Convert CHM to HTML
Converting CHM to HTML is useful when the text of an old help system needs to enter a browser editor, documentation repository, or content migration. It is also easy to misunderstand: a CHM normally contains many HTML topics plus stylesheets, images, navigation data, and other resources, while a download named HTML is one document. This route extracts a readable HTML topic as a practical starting point. It does not promise to merge an entire help system into one website, repair every relative link, carry every CSS rule, or include every asset beside the returned file. The source must already be accessible; no DRM is removed, decrypted, or bypassed.
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Up to 50 MB. Deleted automatically after 30 minutes.
What it does
- Extracts readable HTML content from a CHM package
- Useful for editing a topic or starting a documentation migration
- Provides a single HTML download rather than a viewer application
- No watermark and no sign-up
How to use CHM to HTML
- 1
Select a readable CHM
Upload a help file that you created, own, or have permission to transform. The converter cannot remove DRM, decrypt a protected package, or bypass a vendor's access rules.
- 2
Extract the topic
The server uses extract_chmLib to extract HTML from the CHM and then produces the selected HTML output from the extracted document. The returned file is one topic, not a ZIP containing the whole help project.
- 3
Reconnect what the page needs
Open the HTML in an editor and check its headings, links, images, stylesheet references, encoding, and scripts. Copy permitted assets from the source package locally if the page is going into a real website.
How it works
This page deliberately has an extraction contract rather than a promise to create a
website. extract_chmLib extracts HTML from the CHM into a temporary directory, and
then the selected HTML output is produced from the document the server finds there.
The download is written as one HTML file. That makes it convenient to open, search, or
paste into an editor, but it also explains why a project with 240 topics does not become
a 240-page web site in one click.
CHM navigation is separate from topic markup. The contents tree, index, and context IDs can tell a viewer how to move between documents, while the extracted topic may contain only its own links. A selected page can therefore look complete in a browser while its navigation pane is gone. Check the URL targets and headings before moving content into a new information architecture.
The single-file boundary
HTML is good at referring to companion files, not at magically carrying them along. A topic may point at a CSS file for its typography, an image for a diagram, a font for a special symbol, or a script for a menu. The returned download does not promise a bundled asset directory. If those files are not beside the HTML, a browser may show plain text, broken images, or inert controls. This is a content extraction result, not a full CHM unpack with all relationships repaired.
Simple headings, paragraphs, lists, links, and code blocks are usually the most useful parts to migrate. Frames, viewer-specific commands, generated navigation, absolute positioning, and old browser CSS deserve extra attention. Compare the source topic with the output, then clean the markup in a local editor and add only assets you are permitted to publish. Keep the CHM as the reference copy while the migration is in progress.
Before publishing the page
Open the result with local asset access disabled once, because that reveals hidden dependencies. Search for a phrase with punctuation and test an internal link. Validate the character encoding, inspect screenshots, and decide whether scripts should be rewritten rather than copied. If the goal is an entire manual, plan a batch export and a new navigation model; this single-file tool is intentionally a first step.
Examples
Moving one troubleshooting topic into a CMS
A single topic is the right granularity for a CMS draft. The editor can clean up headings and links without importing the legacy viewer, but should bring over the screenshots and stylesheet deliberately rather than assuming the HTML is self-contained.
Auditing an old documentation set
This output helps inspect what the extraction path can read, but it is not a complete migration. A documentation project should export and organize every topic, map the old contents tree, and copy the assets it is authorized to publish.
Frequently asked questions
Does the HTML download contain the complete CHM help system?
No. A CHM can contain many topic files, while this route returns one discovered HTML document as the selected output. It does not merge every topic, create a ZIP of the project, or reproduce the old help viewer's contents pane. Use the result for a topic, inspection, or migration starting point, and retain the source when a full documentation export is required.
Will the extracted HTML include its CSS, images, and assets?
Not as a promise. The HTML may refer to stylesheets, images, fonts, scripts, or relative files that remain separate from the returned document. Basic markup can be useful immediately, but a browser may show missing images or unstyled content when those companions are absent. Inspect the source package and reconnect permitted resources before publishing the page as part of a website.
Can CHM to HTML remove DRM or protected access?
No. The service does not remove DRM, decrypt an account-controlled file, bypass a vendor license, or make restricted topics readable. `extract_chmLib` must be able to read the input for the conversion to proceed. Upload a file you authored, own, or are explicitly allowed to transform; changing the extension cannot grant a new permission.