HTMLZ to PDB Converter
Convert HTMLZ to PDB 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 an HTMLZ file?
HTMLZ is a zipped container format created primarily for the Calibre eBook management software to package HTML content into a portable eBook structure. It comprises a ZIP archive holding an index.html file, a style.css stylesheet, image assets, and a metadata.opf file following the Open Packaging Format standard. Unlike EPUB, HTMLZ does not enforce the strict containment structure of the IDPF specifications, serving instead as a lightweight wrapper for HTML-based text.
How to open an HTMLZ file
HTMLZ files are natively processed by the Calibre e-book management suite, which can view or convert them to standard formats like EPUB or MOBI. Because the underlying structure is a ZIP archive, users can also rename the file extension to .zip and extract the HTML and CSS components using standard compression utilities like 7-Zip or WinRAR for manual viewing in a web browser.
HTMLZ Technical Info
- Full Name
- Zipped HTML eBook
- Developed By
- Kovid Goyal (Calibre)
- Initial Release
- 2010s
- MIME Type
- application/zip
What is a PDB file?
In the context of eBooks, the PDB (Palm Database) format is a sequential record-based container originally engineered for the Palm OS platform. The file structure consists of a fixed-length header containing metadata (such as Type and Creator IDs) followed by a list of record offsets and the raw data records. For digital reading, these records typically contain text compressed via the PalmDOC (LZ77) or zTXT algorithms, effectively acting as a wrapper for eReader content.
How to open a PDB file
Modern desktop operating systems do not include native handlers for Palm OS databases. Users looking to access eBook content within PDB files should use Calibre or STDU Viewer, which can interpret the specific PalmDOC compression. Note that PDB is also an extension for 'Program Database' debug files in Visual Studio; these are binary disparate and require Microsoft development tools, not eBook readers.
PDB Technical Info
- Full Name
- Palm Database
- Developed By
- Palm, Inc.
- Initial Release
- 1996
- MIME Type
- application/vnd.palm
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Purpose-built for speed, privacy, and breadth of format support.
Convert HTMLZ to PDB in seconds
Every HTMLZ to PDB conversion runs on our servers, so your device stays fast and the output quality stays intact.
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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 HTMLZ to PDB via API
Automate HTMLZ to PDB 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": "htmlz-to-pdb",
"tasks": {
"upload-file": {
"operation": "import/upload"
},
"convert": {
"operation": "convert",
"input": "upload-file",
"output_format": "pdb"
},
"export-result": {
"operation": "export/url",
"input": "convert"
}
}
}'
# 2. Upload your file (use upload_url from the response)
curl -X PUT "$UPLOAD_URL" --upload-file input.htmlz
# 3. Poll for result
curl https://api.runconvert.com/v3/jobs/$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.