What is the ANNOT file format?
An .annot file is an XML companion document created by Adobe Digital Editions (ADE) to store a reader's annotations - highlights, margin notes, and bookmarks - for a specific eBook. Adobe introduced the format with ADE 1.0 around 2007.
Each .annot file is paired with a specific EPUB or PDF title managed by ADE. The XML records each annotation's type (highlight, note, or bookmark), its precise position within the book, any associated note text, the highlight color, and a creation timestamp. The file grows with each new annotation but typically remains small - a few kilobytes even for heavily annotated titles.
On Windows, .annot files are stored in Documents\Digital Editions\Annotations\; on macOS in ~/Documents/Digital Editions/Annotations/. The filename prefix matches the eBook title. Deleting an .annot file removes all annotations for that title but leaves the eBook itself untouched. Annotations cannot be exported to PDF or printed directly from within ADE.
Because the format is plain XML, the contents can be read in any text or XML editor. However, Adobe has not published the schema publicly, and the internal position-reference encoding is ADE-specific and not documented.
Security & safety
RISK: LOWAn ANNOT file is a plain XML text file generated by ADE and contains only annotation metadata - no executable code, no eBook content, no DRM keys. It poses no security risk to open or inspect in a text editor.
Format details
in a nutshell- Hypothesis annotation cache - Some tools cache web annotation data with a .annot extension; unrelated to Adobe Digital Editions.
Programs that open ANNOT files
Windows2 apps
Adobe Digital Editions
Free Open the paired EPUB/PDF in ADE - annotations load automatically from the ANNOT file in the Annotations folder. Do not open the .annot directly. 
Notepad / Notepad++
Free Open the .annot in a text editor to inspect the raw XML annotation entries. 
macOS1 app
Adobe Digital Editions
Free Open the paired EPUB/PDF in ADE; annotations reload from ~/Documents/Digital Editions/Annotations/. Technical details
deep spec| File format | Plain text XML (UTF-8) |
| Annotation types | Highlight, margin note, bookmark |
| Per-annotation metadata | Type, position reference, note text, highlight color, creation timestamp |
| Paired eBook formats | EPUB or PDF managed by Adobe Digital Editions |
| Storage location (Windows) | `Documents\Digital Editions\Annotations\` |
| Storage location (macOS) | `~/Documents/Digital Editions/Annotations/` |
| Schema | Proprietary and unpublished; tied to Adobe Digital Editions release version |
| Typical file size | 1 KB - 50 KB (scales with number of annotations) |
| Effect of deletion | Removes all annotations for the paired eBook; the eBook file itself is unaffected |
| Export capability | Annotations cannot be exported to PDF or printed directly from ADE |
| Encryption / compression | None - plain text file |
| Released | Circa 2007 (with Adobe Digital Editions 1.0) |
| Latest version | No independently versioned spec; tied to Adobe Digital Editions release (ADE 4.x current) |
ANNOT conversions
Community Q&A
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