sigil-ebook/sigil

★ 6,779C++Audience · writerComplexity · 2/5LicenseSetup · moderate

Mindmap

mindmap
  root((Sigil))
    Editing
      HTML per chapter
      CSS styling
      Metadata editor
    Features
      Auto table of contents
      Preview panel
      Version compare
    Plugins
      Python 3 plugins
      MobileRead community
      Validation tools
    Platforms
      Windows installer
      macOS build
      Linux AppImage

mindmap root((Sigil)) Editing HTML per chapter CSS styling Metadata editor Features Auto table of contents Preview panel Version compare Plugins Python 3 plugins MobileRead community Validation tools Platforms Windows installer macOS build Linux AppImage

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Things people build with this

USE CASE 1

Edit the HTML and CSS inside an EPUB file directly to fix formatting issues before publishing to Apple Books or Kobo.

USE CASE 2

Regenerate the table of contents and fix author and title metadata across an entire ebook in one session.

USE CASE 3

Install community Python plugins to validate EPUB 3 structure and check grammar before submitting to a publisher.

USE CASE 4

Compare saved versions of an ebook using the checkpoint tool to see exactly what changed between edits.

Tech stack

C++Python 3HTMLCSS

Getting it running

Difficulty · moderate Time to first run · 30min

Mac builds require assembling several components before compiling from source, Windows and Linux are easier.

Free to use and modify for any purpose, but all modified versions must also be released as open source under the same license.

In plain English

Sigil is a free, open source ebook editor that runs on Windows, macOS, and Linux. It creates and edits books in EPUB format, which is the standard used by most ebook readers and apps such as Apple Books, Kobo, and Adobe Digital Editions. Both older EPUB 2 and newer EPUB 3 files are supported. EPUB files are built from web-style content, so Sigil gives you direct access to the HTML and CSS that make up each chapter and its styling. You can also edit a book's metadata such as title, author, and publication date, generate a table of contents automatically, and run reports to spot issues across the whole file. A built-in preview panel shows how the book will look to a reader, and a checkpoint comparison tool lets you see what changed between saved versions. Sigil includes a plugin system driven by Python 3, which allows optional extensions for tasks like validating EPUB structure, checking grammar, converting file formats, and more. A community-maintained index of available plugins is hosted by the MobileRead forums. A companion application called PageEdit offers a visual HTML editor for those who prefer to write or arrange content without editing code directly. On Windows, Sigil ships as a standard installer and is also available through package managers like winget and Chocolatey. On Linux, the developers provide an AppImage build for systems whose package repositories carry an older version. Mac builds require assembling several components before compiling, and the repository includes step-by-step documentation for each platform. The program is licensed under the GPLv3.

Copy-paste prompts

Prompt 1

I have an EPUB with broken chapter headings and incorrect author metadata. Walk me through using Sigil to fix the HTML structure and update the metadata fields.

Prompt 2

How do I install a Sigil plugin from the MobileRead community index to validate my EPUB 3 file's internal structure?

Prompt 3

Write a Python plugin for Sigil that automatically converts all chapter title tags to h1 and strips inline style attributes across every chapter file.

Prompt 4

How do I compile Sigil from source on macOS following the repository's step-by-step build documentation?

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