Atticus does both jobs in the cloud. Calamus does them natively, offline.

Atticus is the closest product on the market to Calamus, and it is well made. It starts from the same premise: one purchase that both writes the book and produces the file a store will accept, so you are not buying a manuscript organizer and a formatter separately. At $147 one-time with future updates included, it is the least expensive way to get both halves, and it undercuts Vellum by $102 while doing considerably more than Vellum does.

It also runs almost everywhere. Atticus is a web app you install like a program, with its own icon, and that means Windows, Mac, Linux and a Chromebook all get the same thing, which is more than the Mac-only tools can say. It syncs between machines with no Dropbox folder to configure, imports DOCX, exports EPUB, PDF and DOCX, embeds over 1,500 typefaces and prints at real trim sizes. For a Windows author who wants one tool for the whole job, Atticus is a sensible answer, and nothing on this page is going to pretend otherwise.

Calamus is a native Mac and iPad program, written for the machine it runs on. Atticus is a web app with a desktop icon, so a browser engine is doing the work whether or not you can see the browser. Day to day that shows up in small places: how the app feels under sustained typing, how it behaves with a long manuscript open, how quickly it is ready after you open it.

The part worth being precise about is what happens with no connection. Calamus's Mac and iPad apps hold a full local copy of the book, work with nothing available at all, and reconcile on their own when you are back online. How much any given web app can do offline depends on what it has cached at that moment, so rather than characterize somebody else's caching, the claim here is only about what the native apps do, which is work.

On the formatting side the two are genuinely close. Both compile a retailer-ready EPUB and a print PDF at real trim sizes, and the difference is a matter of degree: Calamus embeds more than 1,900 Google typefaces in the exported file against Atticus's 1,500 or so, and also exports Markdown and imports RTF, Markdown and plain text alongside DOCX.

Yes, and the route is short. Atticus exports DOCX, Calamus imports DOCX, and Calamus reads the chapter breaks out of the manuscript itself rather than making you mark each one by hand. Calamus also imports RTF, Markdown and plain text, so a book that has been through several programs on its way here does not need converting first.

What does not carry across is your Atticus formatting: theme, ornaments, trim size and the rest are chosen again at Compile in Calamus, on one screen, and then saved with the book so the next draft and the rest of the series match without being set up again. Chapter structure, text and emphasis come through; layout decisions get made once more.

Take a DOCX export out of Atticus and keep it somewhere separate before you import anything. That advice applies to leaving any program, not to this one in particular.

This is the question where Atticus wins on reach and it is worth being straight about it. Atticus runs on Windows, Mac, Linux and a Chromebook, and every one of those is a first-class way to use it. Calamus's native apps are Mac, iPad and iPhone; on Windows or Linux you get the browser version, which is the full writing app but not a program installed on your machine.

So the platform answer depends on what you own. If your writing happens on a Windows laptop and nothing else, Atticus is built for that and Calamus is not. If you write on a Mac and want to carry the same book to an iPad on the sofa or a phone on a train, Calamus has real apps for all three in the one price, they work offline, and they sync through your account rather than through a file service in the middle.

Atticus organizes a book as a chapter list and gives you a focus mode to write in, which covers the essentials. Calamus is built for writers who are keeping a long series straight and who want the drafting tools as well as the formatting ones.

If you write on Windows, Linux or a Chromebook, stay. Calamus runs in the browser on all of them and that genuinely works, but Atticus is built for those machines and you should not pay more for native apps you cannot install.

If $147 against $189 matters this month, stay. The $42 buys world-building, the drafting tools, the native apps and the extra typefaces, and if you are writing a memoir or a standalone that does not need a Codex, you would be paying for depth you will not open.

If you have already formatted several books in Atticus and your interiors look the way you want them to, that is a real asset and switching means setting those choices up again. Atticus is not a tool anybody needs rescuing from.

One thing to know either way: Atticus has no free trial, only a 30-day money-back guarantee, so trying it means paying first and asking for the money back. Calamus gives you 14 days in the browser with no card, and your files download during the trial even though Compile is held back. If you want to try before you decide, that difference is the one to weigh.