Sigil 2.7.6: ePub editor updates

# Sigil 2.7.6: Key Updates to the ePub Editor for Developers

On March 20, 2026, version 2.7.6 of the open-source e-book editor Sigil was released. This cross-platform solution based on Qt6 and QtWebEngine is designed for working with ePub 2 and ePub 3 formats. The code is written in C++ and Python, distributed under GPL v3.0 on GitHub. It supports Windows 10 (1809+), macOS 11 Big Sur and later, and Linux including Flatpak.

The version focuses on fixing 10 bugs, boosting performance, and adding features. Developers will enjoy improved stability when editing EPUB files.

Main Changes in the Release

The update affects several critical areas. Here's the full list of key fixes and new features:

• Ability to unset environment variables via the env-vars.txt file. This simplifies environment setup without messing with system variables.
• Fixed incorrect translations from Transifex that previously broke the interface localization.
• Fixed layout error in the Clips window (Dock widget), which caused UI crashes.
• Recommendation for Windows users: update the Visual Studio VC++ redistributable if the app won't launch.

These changes boost the tool's reliability for mid- and senior-level developers working with ePub content.

Technical Details and Compatibility

Sigil uses Qt6 for cross-platform support, ensuring a consistent experience across all operating systems. The Linux build via Flatpak minimizes dependencies. For Windows, the minimum version is 10 (build 1809), which is relevant for enterprise environments.

Performance has been optimized: bug fixes reduce the load on QtWebEngine when rendering complex ePub 3 files. Developers integrating Sigil into pipelines will appreciate the improved Clips handling—a panel for storing code snippets and text fragments.

Example setup for env-vars.txt to disable variables:

# env-vars.txt
# Line to unset a specific variable
unset QT_AUTO_SCREEN_SCALE_FACTOR

Place the file in the application directory. This is handy for debugging in containerized environments.

Upgrade and Usage Recommendations

Before upgrading, check compatibility:

• Windows: Install the latest Visual C++ Redistributable (x64/x86).
• macOS: Requires Big Sur or later. Check QtWebEngine on M1/M2.
• Linux: Flatpak version is isolated; update via flatpak update.

After installation, test Clips: create a new clip, drag it to the Dock—the layout shouldn't break. For localization, manually refresh the Transifex cache if translations don't load.

Sigil remains the go-to choice for programmatic ePub editing: Python scripts enable automating validation and conversion.

Key Takeaways

• 10 bug fixes: Critical UI and localization issues resolved.
• env-vars.txt: New way to control the environment without system privileges.
• Clips Dock: Proper widget layout restored.
• Windows fix: VC++ Redistributable update required to launch.
• Performance: Qt6 optimizations for ePub 3 rendering.

— Editorial Team