Talmaara

Talmaara is a worldbuilding workspace with a book editor built into it. Everything in your world shares a single timeline, even across multiple worlds.

Every date you enter — a king's death, a war, an era, a scene in chapter nine — is stored as pure math along the timeline. It doesn't matter that you invented a planet with 19-hour days, a 400-day year, five made-up months, and a calendar that has 5 eras. Underneath, it all reduces to the same math, so everything you write down can line up with everything else on its own.

Key features no other site has:

• The timeline fills itself in. You never "add" anything to a timeline. Give a character a birth and a death and their lifespan appears automatically; give an event a start and an end date and it just appears; every world aligns together to show where their eras start and end; Add a date to a scene in your book and it lands there too, right next to the history it happens in; Zoom from a single night out to ten thousand years.
• The family tree works out the words for you. You only ever record parents, children, and marriages. Talmaara figures out the rest — siblings, half-siblings, step-siblings, aunts and nephews, "second cousin once removed," "great-great-grandmother." Add one brother to a character and a whole branch of correctly labeled cousins appears, four and five steps out. You never type the word cousin.