Flipbooks AI vs Sigil: Should Your Book Be an EPUB File or a Link?

The Short Answer

Choose Flipbooks AI if the thing you want to hand someone is a link. Your PDF is finished, the layout matters, and you want a reader to open it in whatever browser they already have, on a phone or a laptop, with no download, no app and no account. You want it to look like yours, with your logo and your colours on the paid plans, and you want it to stay online until you take it down. Nothing about that is a job an EPUB editor does.

Choose Sigil if you are making an ebook file and you need real control over what is inside it. Sigil is free, open source and runs on your own machine, and it lets you work directly on the XHTML and CSS that make up an EPUB, fix the metadata, repair the table of contents and check that the file is valid before it goes anywhere near a store. It costs nothing, it works with no account and no internet connection, and it produces the file format that ebook retailers actually take. Flipbooks AI does not edit anything, does not produce an EPUB, and cannot put your book on a storefront.

Flipbooks AI vs Sigil at a Glance

Flipbooks AI wins 7 of these 11 rows, ties 4 and loses none. They are rows we picked, so read them that way. The sections below say plainly where Sigil is the better buy.

Pricing Compared

Sigil is free. Not free with a paid tier waiting at the end of a trial, and not free with a watermark: it is open source software maintained by volunteers, and there is no licence to buy, no account to make and no upsell inside it. That is not a small thing to compete with, and it would be dishonest to write around it. If your only constraint is money, the comparison stops here and Sigil wins. Projects like this do ask for donations and they depend on people contributing time, which is worth knowing if you rely on the tool, but nothing about using it costs you anything.

Flipbooks AI has a free plan that also costs nothing and never expires, and then a paid ladder in US dollars, the same price wherever in the world you buy it. Starter is $59 a year, sold annually only. Plus is $14 a month or $108 a year. Ultra is $29 a month or $228 a year. Those were the figures on our pricing page in August 2026, and they sit on one page rather than being assembled from a table somewhere. What the money buys is described further down, but the short version is that it buys how the flipbook looks and behaves for the person reading it, not storage and not seats.

The comparison that matters is not really $0 against $59, because the two products are not substitutes. Sigil is a cost of nothing and a cost of your time: it assumes you are willing to look at markup when something goes wrong, and the thing you get out of it still has to be hosted or sold somewhere. Flipbooks AI is a cost of money and almost none of your time: you upload a finished PDF and a working link exists. Plenty of people end up paying for one and using the other for free, which is a perfectly sensible outcome.

What Each Free Plan Really Gives You

Sigil does not have a free plan, it has no plan at all, and everything the software does is available to everyone. That includes the code view, the live preview, the metadata editor, the spellchecker, the validation checks against the EPUB specification, and support for both EPUB 2 and EPUB 3. There is no export limit, no watermark on your output and no feature held back for a paid tier that does not exist. For a working writer or editor that is an unusually clean deal, and it is the reason Sigil has stayed in people's toolchains for years.

The Flipbooks AI free plan is narrower but it is a real plan rather than a trial. It keeps three flipbooks live at a time on 1 GB of storage, with the magazine page turn effect and a small Flipbooks AI mark in the corner of the viewer. There is no page cap, so a three hundred page catalogue goes up whole, no ads sit beside it, readers never need an account, and the flipbook is never listed in any public directory. There is no inactivity rule either: a flipbook nobody opens stays online until you delete it.

The three flipbook allowance is a rolling one rather than a lifetime count. Delete one and the slot comes back straight away, so a free account can publish far more than three documents over a year as long as three are live at any moment. One shared password is allowed on the free plan. What free does not include is your own logo, brand colours for the reader controls, the other page turn effects, the embed code, background music or per reader passwords. Those sit on the paid tiers, and every one of them is about the reading experience rather than about how much you may upload.

Branding and Watermarks

Sigil puts nothing on your book. There is no watermark, no maker mark, no line of credit in the metadata and no branding of any kind in the file it writes, because the file it writes is your file and the software goes no further than your hard drive. This is one of the genuine advantages of a desktop tool over a hosted one, and it applies at a price of zero. If unbranded output is the whole of your requirement, you do not need to read the rest of this section.

Flipbooks AI is a hosted viewer, so there is a mark to talk about. On the free plan a small Flipbooks AI mark sits in the corner of the viewer, not across your pages: your artwork is never stamped and there are no ads. Every paid plan removes that mark or swaps in your own logo, starting with Starter at $59 a year, and the same tier unlocks brand colours for the reader controls so the chrome around your pages matches your palette instead of only carrying your logo.

Where this genuinely differs is in what branding even means for each output. An EPUB inherits its identity from your cover and your stylesheet, and the retailer's app draws the rest of the interface, so there is no viewer of yours to brand in the first place. A flipbook is the whole reading surface, so the logo, the colours and the page turn are all things a reader notices. If you want a branded reading experience rather than a branded file, that is the argument for paying for one here, and if you want a file with nothing of anyone else's on it, Sigil already does that for free.

Privacy and Who Can Find Your Flipbook

Sigil is the more private of the two by construction, and there is no argument to be had about it. It runs offline on your own computer, it does not need an account, it does not upload your manuscript anywhere, and nothing about your book leaves the machine unless you send it. For a manuscript under embargo, a client's confidential document or anything you simply do not want sitting on someone else's server, a local editor is the correct answer and a hosted service is not.

Flipbooks AI keeps a flipbook private by link. It is never listed in a public directory, we never submit it to search engines, and readers do not need an account to open it. A single shared password is available on the free plan, and Ultra at $228 a year gives each reader a separate password. Those controls are real and they cover the ordinary cases, which is a document you want to share with a defined group rather than with the whole web.

One caveat deserves to be blunt, and it is about our product rather than theirs. A shared link is a public URL, and if it ends up somewhere crawlable it can be found. On Flipbooks AI the password gates the reader interface rather than the file behind it, so a document that genuinely must not leak needs a system with real access control, not a flipbook. This is exactly the case where Sigil, or any workflow that keeps the document on your own machine until you deliberately hand it over, is the safer choice. Say the sentence out loud before you upload: if this link reached the wrong person, what happens?

Embedding and Sharing

Sharing is where the two products stop resembling each other at all. Sigil produces a file, so sharing means moving that file: uploading it to a retailer, attaching it to an email, dropping it into a shared folder, or sideloading it onto someone's ereader. The recipient needs an app that opens EPUBs, and what they see is decided by that app rather than by you. That is the correct behaviour for an ebook, since reflowing to the reader's screen and font size is the point of the format, but it means you cannot predict the layout and you cannot put the book inside a web page.

Flipbooks AI shares a link. The reader taps it, the flipbook opens in their browser at whatever size their screen is, the pages turn, and nothing is downloaded or installed. On Plus, $14 a month or $108 a year, you also get an embed code and an allowed domain list, so the flipbook can sit inside your own website and you can control which other sites are permitted to frame it. That is the piece Sigil has no equivalent for, because an EPUB does not go in a web page.

If your book has to be sold in a store, Sigil is on the right side of that line and we are not: we do not produce EPUB or MOBI, we have no route to Kindle Direct Publishing, Apple Books or Kobo, and no amount of paying us changes it. If your book has to appear on your own site, in a newsletter, behind a QR code on a poster or in a message where the recipient will not install anything, we are on the right side of it and Sigil is not. Plenty of books need both, and running both is not a compromise.

Ease of Use and What Each Tool Is For

Sigil is a serious editor and it is honest about what it expects from you. There is a visual preview and a metadata editor, but the reason people keep it around is the code view: when a chapter breaks, when a store rejects a file, when the table of contents points at the wrong place, Sigil is where you open the XHTML and fix it. That is a proper skill and it is not for everyone. Someone who has never seen a CSS rule will find it steeper than a formatting app that hides all of this, and they will also find that when something goes wrong, the app that hides it cannot help them.

Flipbooks AI expects almost nothing. There is no template gallery, no in tool page editor, no custom domains, no team seats, no API, no reader analytics, no lead capture forms and no e commerce. You upload a finished PDF, pick a page turn effect, set a password if the document is private, add your logo and colours if you are paying, and share the link. The design work happened wherever you made the PDF, which is deliberate: we are not trying to be the place your book gets written or laid out.

So the split is clean. Sigil is for the construction and repair of an ebook file, aimed at people who want the file to be exactly right and are willing to look inside it. Flipbooks AI is for the distribution of a finished, fixed layout document to people who should not have to think about formats at all. A novel going to retailers belongs in the first. A brochure, a catalogue, a report, a lookbook or a sample chapter you want a stranger to read in one tap belongs in the second. Neither tool is trying to take the other's job, and the reason this page exists is that the two get compared anyway.

Who Should Choose Which

Choose Flipbooks AI if

• What you want to hand someone is a link rather than a file they have to open in an app
• Your layout is fixed and must look identical on every screen, which an EPUB deliberately will not do
• You want the document embedded in your own site, with control over which other sites may frame it
• You want your own logo and brand colours around the reading experience, from $59 a year

Choose Sigil if

• You are producing an EPUB for a retailer and the file has to validate cleanly
• You want to edit the XHTML, the CSS, the metadata or the table of contents directly
• You need the whole job to happen offline on your own machine, with nothing uploaded anywhere
• You want capable software that costs nothing at all, with no plan, no account and no upsell

How to Switch from Sigil to Flipbooks AI

There is nothing to import, because a flipbook is always generated from a source document and an EPUB is not that document. In practice this is less a switch than a decision about which copy of your book is the link, so most people keep Sigil for the file and add a flipbook for the version they send to humans.

1. Decide which document is the link. A store copy and a sharing copy are different jobs. Keep the EPUB for retailers and sideloading, and pick the thing you actually want people to open in a browser: a sample chapter, the full book, a press kit, a catalogue or a proof for a reviewer. That choice decides everything else here.
2. Go back to the layout, not to the EPUB. An EPUB reflows and has no fixed pages, so converting one to PDF gives you an unpredictable result. Export a fresh PDF from wherever the book was actually laid out, so the type stays sharp, the images stay at full resolution and internal links survive.
3. Check the pages before you upload. Confirm the page size is consistent, that facing pages read correctly as spreads, that the cover is the first page and that nothing important sits in the trim area. A flipbook shows two pages side by side on a wide screen, so a document laid out as single pages will still work but will look different from print.
4. Upload the PDF to Flipbooks AI and set it up. Drop the file on the create page, choose a page turn effect, add a password if the document is not for everyone, and set your logo and brand colours if you are on a paid plan. Preview it before publishing, and remember the free plan keeps three flipbooks live at a time with the magazine effect.
5. Put the link where people already are. Replace the file attachment in your email signature, your newsletter and your site with the flipbook URL, and use a QR code for anything printed. If you are embedding it on your own site, that arrives with Plus along with the allowed domain list, so only the sites you name can frame it.

Frequently Asked Questions

Is Sigil free, and what does the free version include?

Sigil is entirely free and open source, with no paid tier, no trial period and no account to create. Everything the software does is available to everyone: the code view for editing XHTML and CSS, the live preview, the metadata editor, the spellchecker, the validation checks against the EPUB specification and support for both EPUB 2 and EPUB 3. There is no export limit and nothing is watermarked. It is maintained by volunteers and it accepts donations, so if you depend on it, supporting the project is worth considering, but using it costs nothing at all.

Can Sigil make a flipbook or host my book online?

No, and it is not meant to. Sigil is a desktop editor that produces an EPUB file, so the output is something you upload, attach or sideload rather than something that lives at an address. There is no hosting, no viewer, no link to share and no page turn animation, because none of that is what an ebook file does. If you want a reader to open your book in a browser with no download, that is the job Flipbooks AI does, and the two happily coexist: keep Sigil for the store file and publish a PDF version as a flipbook for everything else.

Do I need to know HTML to use Sigil?

Not to open a file and change a word, but the tool becomes genuinely useful when you are willing to look at the markup. Sigil gives you direct access to the XHTML and CSS inside an EPUB, which is precisely why people reach for it when a chapter breaks or a retailer rejects a file. If you have never seen a CSS rule, expect a learning curve steeper than a formatting app that hides all of this from you. The trade is real: the app that hides the markup also cannot help you when the markup is the problem.

Does Sigil put a watermark or branding on my ebook?

No. Sigil writes your file and adds nothing of its own: no watermark, no maker mark, no credit line and no branding in the metadata. That is one of the genuine advantages of a desktop tool over a hosted service, and it applies at a price of zero. Flipbooks AI, being a hosted viewer, does place a small mark in the corner of the viewer on the free plan, never across your pages. Every paid plan removes it or swaps in your own logo, starting at $59 a year with Starter.

Can I turn a Sigil EPUB into a Flipbooks AI flipbook?

Not directly, and converting the EPUB is the wrong route anyway. An EPUB reflows to the reader's screen and has no fixed page boundaries, so a PDF made from one will paginate unpredictably. Go back to wherever the book was laid out and export a fresh PDF from there, then upload that. It takes about a minute and the result keeps sharp text, full resolution images and working internal links. There is no import path from any tool into Flipbooks AI, because a flipbook is always generated from a source document.

Which one is more private?

Sigil, clearly, and by design rather than by policy. It runs offline on your own computer, needs no account and never uploads your manuscript, so a confidential document simply never leaves your machine. Flipbooks AI keeps a flipbook private by link, never lists it in a directory and never submits it to search, with a shared password on the free plan and per reader passwords on Ultra. But a link is a public URL, and our password gates the reader interface rather than the file behind it, so anything that genuinely must not leak needs real access control rather than a flipbook.

Can I sell a Flipbooks AI flipbook the way I sell an EPUB?

No. There is no e commerce, no paywall and no storefront integration in Flipbooks AI, and we produce no EPUB or MOBI, so there is no route to Kindle Direct Publishing, Apple Books or Kobo. Selling a book means producing a file a retailer accepts, which is exactly the job Sigil helps with. What a flipbook is good for is the free side of publishing: a sample chapter, a press kit, a catalogue, a media pack or a proof you want someone to read in one tap without installing anything.

Does a flipbook look the same as my print layout?

Yes, and that is the main reason to use one for a designed document. A flipbook is built from your PDF, so the typography, the margins and the artwork stay exactly where you put them on every screen, with two pages shown side by side on a wide display. An EPUB does the opposite on purpose: it reflows to the reader's device and font size, which is right for a novel and wrong for a magazine or a catalogue. Pick by the document, not by the format.

What does Flipbooks AI cost, and what do the paid plans add?

The free plan costs nothing and does not expire: three flipbooks live at a time, 1 GB of storage, no page cap, no ads and one shared password. Starter is $59 a year, annual only, and removes the corner mark or swaps in your own logo, unlocks brand colours for the reader controls and opens the page turn effects the free plan does not carry. Plus is $14 a month or $108 a year and adds the embed code with an allowed domain list. Ultra is $29 a month or $228 a year and adds background music and a separate password for each reader. Those prices were current in August 2026.

Is Sigil a good tool?

Yes, and unusually so for something that costs nothing. It has been the reliable answer for years to a specific and painful problem, which is that ebook files break in ways only direct access to the markup can fix, and it does that job on Windows, macOS and Linux, offline, with no account and no upsell. Being open source, it can be inspected and it cannot quietly change its terms on you. The honest split is simply that Sigil builds and repairs a file for retailers and readers with ereader apps, while Flipbooks AI publishes a finished PDF at a link for people who will not install anything.