CHM to OEB Converter
Convert CHM to OEB online for free. Fast, secure, and high-quality conversion with no sign-up or software required.
Maximum file size is 1GB
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Three steps to your converted file
Everything happens in your browser tab - upload, pick a format, download. The heavy lifting runs on our servers.
Upload your file
Drag and drop, click to browse, or paste a URL. Batches take up to 20 files at once - 230+ input formats across video, audio, image, document, and archive types.
Choose an output format
Pick from over a hundred output formats. Filter by category or search by name - every option is open to everyone, no account needed.
Convert & download
Hit Convert and grab your download link moments later. Originals are erased when the job completes; results are cleared within about an hour.
What is a CHM file?
The CHM (Compiled HTML Help) format is a proprietary binary documentation format developed by Microsoft for software help files. It encapsulates a collection of HTML pages, hyperlinks, and image assets into a single LZX-compressed archive, indexed via a binary table of contents (HHC) and keyword index (HHK). The format relies on the Information Tech Storage (ITS) file system structure, allowing for rapid random access and full-text search capabilities within the Windows Help environment.
How to open a CHM file
Windows operating systems provide native support via the built-in Microsoft HTML Help Executable (hh.exe). On macOS and Linux systems, which lack the proprietary Windows API, third-party viewers are necessary. KchmViewer is a standard solution for Linux/KDE environments, while xCHM provides cross-platform compatibility for macOS and BSD distributions.
CHM Technical Info
- Full Name
- Microsoft Compiled HTML Help
- Developed By
- Microsoft
- Initial Release
- 1997
- MIME Type
- application/vnd.ms-htmlhelp
What is an OEB file?
The Open eBook (OEB) format, formally defined by the Open eBook Publication Structure (OEBPS) specification, is a legacy XML-based standard developed by the Open eBook Forum (now IDPF) in 1999. It acts as a manifest file (typically with an .opf extension) that references a package of HTML or XHTML content, CSS stylesheets, and Dublin Core metadata. As the immediate predecessor to the modern EPUB standard, OEB established the structural protocols for separating content from presentation in digital publishing.
How to open an OEB file
OEB files are not natively executable on standard operating systems. To view the content properly assembled, users must utilize dedicated eBook software such as Calibre, which parses the OEBPS manifest to display the book. While the underlying XML and HTML components can be viewed in standard text editors like Notepad++ or Visual Studio Code, this does not render the formatted eBook experience.
OEB Technical Info
- Full Name
- Open eBook Publication Structure
- Developed By
- Open eBook Forum
- Initial Release
- 1999
- MIME Type
- application/x-oeb1-document
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Purpose-built for speed, privacy, and breadth of format support.
Convert CHM to OEB in seconds
Every CHM to OEB conversion runs on our servers, so your device stays fast and the output quality stays intact.
Fast, cloud-powered
No queue, no waiting. Files are processed on high-performance servers and returned in seconds, even for large files.
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Encrypted in transit and never shared with anyone. Uploads are erased the moment your job completes, and results shortly after.
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Developer API
Convert CHM to OEB via API
Automate CHM to OEB conversions in three steps: create a job, upload your file, then poll for the result.
# 1. Create job
curl -X POST https://api.runconvert.com/v3/jobs \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"tag": "chm-to-oeb",
"tasks": {
"upload-file": {
"operation": "import/upload"
},
"convert": {
"operation": "convert",
"input": "upload-file",
"output_format": "oeb"
},
"export-result": {
"operation": "export/url",
"input": "convert"
}
}
}'
# 2. Upload your file (use upload_url from the response)
curl -X PUT "$UPLOAD_URL" --upload-file input.chm
# 3. Poll for result
curl https://api.runconvert.com/v3/jobs/$JOB_ID?include=tasks \
-H "Authorization: Bearer YOUR_API_KEY"Replace YOUR_API_KEY with your RunConvert API key. Get your free API key at runconvert.com/api.