Is it a Virus?
✔ NO - Safe
Must be located in C:\Program Files\Sigil\ or C:\Program Files (x86)\Sigil\
Warning
Background tasks normal
Sigil may spawn background workers for file I/O, validation, and plugin loading
Can I Disable?
✔ YES
Close editor to stop, or disable startup integration via Windows Task Manager
What is sigil.exe?
sigil.exe is the Windows executable for the Sigil eBook Editor, a cross-platform, open-source tool for creating and editing EPUB files. It runs as a standalone process and may spawn worker threads for rendering, text editing, and background I/O to keep the UI responsive.
Sigil uses a Qt/GTK-based UI and a native Windows build to manage EPUB structure, metadata, and validation. It operates with a main UI process and background threads for tasks like packaging and syntax checks to keep editing smooth.
Quick Fact: Sigil supports multiple editor panels within a single project, with background tasks ensuring responsiveness during export and validation.
Types of Sigil Processes
- Main UI Process: Primary Sigil window and menus
- Editor Worker: Text editor and EPUB content handling
- Metadata Manager: Library of book metadata and validation
- Packaging Worker: EPUB packaging and validation tasks
- Plugin Loader: Optional plugins and extensions
- Background I/O: File read/write and autosave operations
Is sigil.exe Safe?
Yes, sigil.exe is safe when it's the legitimate file from Sigil Project downloaded from official sources (sigil-ebook.org or the GitHub releases).
Is sigil.exe a Virus or Malware?
The real sigil.exe is NOT a virus. However, malware sometimes masquerades with similar names to trick users.
How to Tell if sigil.exe is Legitimate or Malware
- File Location: Must be in
C:\Program Files\Sigil\ or C:\Program Files (x86)\Sigil\. Any sigil.exe elsewhere is suspicious.
- Digital Signature: Right-click the file in Explorer → Properties → Digital Signatures. Should show signer such as "Sigil Project" or "Kovid Goyal".
- Resource Usage: Normal usage is typically under 8% CPU and 60-260 MB memory during editing; persistent high usage may indicate issues.
- Behavior: Sigil should launch from a trusted shortcut or Start Menu. Unexpected auto-start or background processes may indicate malware.
Red Flags: If sigil.exe is found outside the Sigil directory, lacks a valid signature, or runs unseen in the background, run antivirus and verify the origin from sigil-ebook.org or GitHub releases.
Why Is sigil.exe Running on My PC?
sigil.exe runs when you open Sigil to edit EPUB files or when certain background tasks are configured (autosave, plugin loading, or packaging).
Reasons it's running:
- Active Editing: You're editing an EPUB project; the editor creates worker processes to manage content rendering and syntax checks.
- Background Plugins: Plugins or extensions loaded by Sigil may run background tasks for features like validation or metadata checks.
- Autosave and Recovery: Sigil frequently saves work to prevent data loss; this creates background I/O activity.
- EPUB Validation: Packaging or validation steps run to verify EPUB structure and metadata before export.
- Startup Registration: If Sigil is configured to start with Windows, the process may start at login even when not actively editing.
Can I Disable or Remove sigil.exe?
Yes, you can disable sigil.exe. It's safe to exit Sigil when not editing, and you can uninstall Sigil entirely if you no longer need it.
How to Stop sigil.exe
- Close Sigil: Click the close button or use File → Quit to terminate the application.
- End Background Tasks: In Task Manager, locate sigil.exe and End Task if it remains active after closing.
- Disable Startup: Task Manager → Startup tab → Disable Sigil
- Disable Autosave: Within Sigil options, turn off autosave or set a longer interval.
- Uninstall Sigil: Windows Settings → Apps → Sigil → Uninstall
How to Uninstall Sigil
- ✔ Windows Settings → Apps → Apps & Features → Sigil → Uninstall
- ✔ Control Panel → Programs → Uninstall a program → Sigil → Uninstall
- ✔ Delete remaining Sigil folders in AppData if present
Common Problems: High CPU or Memory Usage
If sigil.exe uses too many resources:
Common Causes & Solutions
- Excessive Open Files: Close large EPUB projects or split work into smaller parts; one big project can strain memory.
- Background Plugins: Disable or remove unused plugins under Preferences or Plugins Manager.
- Large CSS or Fonts: Complex styles or embedded fonts can cause overhead; optimize by simplifying styles and font usage.
- Outdated Sigil: Update to latest release from sigil-ebook.org or GitHub.
- Disk I/O Bottlenecks: Move projects to a faster SSD; ensure antivirus isn't scanning files in real time.
- Corrupt Project: Try opening a backup or a small sample book; create a new project and import content gradually.
Quick Fixes:
1. Close large or unused EPUBs to free memory
2. Disable non-essential plugins in Sigil
3. Update Sigil to latest version
4. Check for disk I/O throttling by antivirus
5. Restart Sigil and reopen the project
Frequently Asked Questions
Is sigil.exe a virus?
No, the legitimate sigil.exe from Sigil Project is not a virus. Verify the file path is C:\Program Files\Sigil\ or C:\Program Files (x86)\Sigil\ and that the signer is 'The Sigil Project' or 'Kovid Goyal'.
Why is sigil.exe using CPU when idle?
Sigil may run background validation or auto-save tasks. Check Plugins Manager and disable unnecessary plugins; ensure you're not editing large EPUBs while idle.
Can I delete sigil.exe?
Yes, you can uninstall Sigil via Windows Settings. Your open projects will be affected; back up first and you can reinstall later from official site.
Can I disable sigil.exe from starting with Windows?
Yes, disable startup entry in Task Manager → Startup or in the Windows Settings.
How do I update Sigil to the latest version?
Visit sigil-ebook.org or the GitHub releases page and install the new version. Your settings and projects are preserved with standard installations.