Sigilvs
Calibre
Calibre: For library management and format conversion rather than precise editing of the EPUB source
Sigil
Open source EPUB editor for working directly on the file, not generating it
As of 31 August 2026, Sigil is free to use. A free, volunteer-maintained EPUB editor that opens the container itself: the XHTML files, the stylesheet, the OPF metadata and the spine order. Softwr lists it under Publishing. Sigil is made by Sigil (community maintained), available on Windows, macOS, Linux.
Overview
What Sigil does
Sigil is a desktop EPUB editor released under the GPL and available for Windows, macOS and Linux. It handles EPUB 2 and EPUB 3, presents a code view alongside a rendered preview, and gives direct access to every component of the book: the individual XHTML chapter files, the CSS, the metadata in the OPF, the navigation document and the reading order. It includes regular expression find and replace across all files at once, spell checking, a table of contents generator, validation, and a Python plugin framework that the community has used to build converters and checking tools. What separates Sigil from everything else in this category is direction of travel. Vellum, Atticus and Pressbooks generate an EPUB from a manuscript, and if the result is wrong your only recourse is to change the input and export again. Sigil edits the EPUB itself, which means a validation error, a broken internal link, a font that will not embed, or a stylesheet a retailer rejects can be corrected in the file that is actually being uploaded. Anyone who has had a book rejected by a retailer validator understands why that matters, and it is the reason Sigil remains in use long after prettier tools appeared. The cost is that it assumes competence. Beyond basic text editing you need working HTML and CSS, because the interface deliberately exposes the markup rather than hiding it. There is no cloud sync, no collaboration, no print output and no distribution, and development depends on a small group of volunteer maintainers rather than a company. It is a specialist repair and finishing tool, and it is very good at being exactly that.
What people use it for
- Fixing an EPUB that a retailer validator has rejected, without re-exporting from the tool that generated it
- Correcting the table of contents, reading order or metadata in a file supplied by a conversion service
- Preparing a back-catalogue title where the only surviving source is the EPUB itself
- Applying a consistent stylesheet or a bulk text correction across every chapter of a book at once
Related searches
The honest half
Where it falls short
Concrete and checkable, so you can decide whether any of them matter to you. This is the half of a review a vendor will not write about Sigil.
- It produces no print output whatever, so any book that needs a paperback interior requires a completely separate tool and a second workflow.
- Meaningful use requires reading and writing HTML and CSS, which puts it out of reach of most authors who simply want a finished file.
- There is no cloud storage, sync or collaboration, so the book exists as a file on one machine and version control is whatever you set up yourself.
- Development depends on a small number of volunteer maintainers, so release timing and platform builds follow their availability rather than a roadmap, and a lapse in maintenance would leave no obvious successor.
- It provides no distribution, no retailer connection and no Kindle-native output, so it sits in the middle of a workflow that other tools have to complete on both sides.
Cross-shopped
What people choose instead of Sigil
Each pairing was judged by two reviewers asking whether a buyer would genuinely weigh the two against each other. The ones that failed were deleted rather than published.
- SigilvsVellum
Vellum: If you want a finished, typeset EPUB and print interior generated for you and never intend to touch markup
Pricing
What Sigil costs
Taken from the vendor's own pricing page. Prices move, so check before you buy.
Sigil
Free
- GPL licensed with no cost or account required
- Full functionality with no feature gating
- Community support through forums and the issue tracker
- Source available for anyone to build or modify
Capabilities
Features
Direct EPUB editing
Opens and saves the EPUB container, editing XHTML, CSS, OPF metadata and spine order in place
Code and preview views
Markup editing beside a live rendered preview of the same page
EPUB 2 and EPUB 3
Support for both specifications, including converting between them
Regex across files
Regular expression find and replace applied across every file in the book at once
Validation
Built-in well-formedness checking with EPUB validation available through the plugin framework
Python plugins
An extension framework used by the community for conversion, cleanup and checking tools
Answered, with sources
Questions people ask
Each answer names the page it came from, so you can check it rather than take our word for it.
Can I write my book in Sigil?
You can, but you should not. It is an EPUB editor, not a word processor, and writing long-form prose in it is unpleasant. Write elsewhere, import, then finish in Sigil.
Does it make Kindle files?
Not natively. Produce a valid EPUB in Sigil and let Amazon convert it, or use a separate conversion tool for other Kindle formats.
Is it safe to rely on a volunteer project for commercial work?
The files it produces are standard EPUB, so nothing is locked in. The risk is that maintenance stops, not that your books become unreadable.
Keep looking
Where to go from Sigil
- Sigil alternativesEvery product people weigh against it
- Sigil pricingPlans, floors and what the tiers exclude
- Sigil badgesWhich rules it meets, and the figure behind each
- All Publishing softwareThe full category
- Best Publishing softwareThe shortlist, and how it was cut
Best Publishing software for
Compare Sigil with
- Calibre
- GIMP
- Pressbooks
- Scribus
- Moon Reader
- Affinity Publisher
- Atticus
- Kobo
- Reedsy
- Blurb
- Draft2Digital
- IngramSpark
- Libro.fm
- Calibre
- Affinity Publisher
- Atticus
- Kobo Writing Life
- Kobo
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From $147/one-time11 researched notesRakuten Kobo self-publishing platform paying a 70% royalty with no delivery fee deduction and no upper price cap, a materially different structure from Amazon KDP
Free plan11 researched notesRakuten e-reader hardware, app and ebook store, the reader-facing side of the Kobo ecosystem
Free plan11 researched notes
Softwr does not host reviews and shows no star rating for Sigil, because a rating we did not collect is not ours to publish. What is here is the pricing and platform detail from the vendor’s own pages, limitations we could state concretely, and alternatives a reviewer confirmed people weigh against it. Tell us if any of it is wrong.
More on Sigil
Sigil alternatives
What people switch to, and what they give up
Sigil pricing
Every tier, and where the cost actually lands
Compare Sigil
Put it head to head with anything we hold
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Best Publishing software alternatives
Amazon self-publishing platform that is free to use, earning Amazon a royalty cut instead of a fee, with a hard price band and per-megabyte delivery cost governing the 70% rate
Free to publish; Amazon earns a royalty share rather than a feeRakuten e-reader hardware, app and ebook store, the reader-facing side of the Kobo ecosystem
Free store and app; hardware sold separately; optional subscriptionAudiobook subscription that splits revenue with an independent bookstore of your choice
Per credit per month, credits never expire
Unlimited ebook, audiobook, magazine and sheet music subscription, the consumer reading service formerly called Scribd
Per user per month, unlimited
Amazon-owned book cataloguing, review and recommendation app
Free, no subscription or in-app purchases; funded by Amazon as a commerce and data feeder
Pay-per-book self-publishing service for ebook conversion, print on demand and distribution
One-time purchase per project
Amazon's consumer e-book reading app, distinct from Kindle Direct Publishing, the author-facing service
Free app, revenue from book purchases and optional subscriptionRakuten Kobo self-publishing platform paying a 70% royalty with no delivery fee deduction and no upper price cap, a materially different structure from Amazon KDP
Free to publish; Kobo earns a royalty share rather than a fee