Synopsis, logline, and blurb: what each one is for and what readers of it look for
A synopsis is not written for readers. It is written for an agent, an editor, or a contest juror, and it follows rules that are the opposite of the manuscript's. The manuscript withholds; the synopsis reveals everything, including the ending. A synopsis that ends "but will she discover the truth?" is the first thing a jury sets aside. This tool enforces the rule: if your input has no ending, it invents a placeholder and flags it, so you can replace it with your own before you submit.
The output has four sections. A logline: protagonist, goal, obstacle, and stakes in one or two sentences. A pitch paragraph: why this story, why now, and who it is for, which is the section a query letter borrows. Character notes: the two or three people who matter, described by their function and arc rather than their appearance. And the synopsis proper: beginning to end, in chronological order, in present tense, typically between five hundred and a thousand words. Each section is written so it can be lifted out on its own.
Different destinations want different shapes. A fiction query usually wants a one-page synopsis with the ending; screenplay contests often want a logline, a one-paragraph synopsis, and sometimes a treatment; television pitches want a series overview and an episode breakdown. Tell the tool the purpose and it adjusts section order and length. If you have the actual submission guidelines, paste their section headings into the input and the output will follow them.
Writing a synopsis exposes the book's weak points, which is why it is worth doing before the manuscript is finished. If the middle of Act Two collapses into one sentence, that stretch is underbuilt. If you cannot describe a character's arc, that character is a function rather than a person. Many writers use this tool at the outline stage and again at the halfway mark, not only at submission time.
The free version runs three times a day without an account, and nothing you enter is used for training. To keep a synopsis in sync with a manuscript as it changes, store it in the Studio story bible next to your chapters.