❓ Problem

Picking your next book is weirdly hard work. You scroll reviews, ask a friend, check TikTok, add the title to a "want to read" shelf that's already 400 books deep, then end up rereading something you've read twice.

And reading time is getting scarcer. The share of Americans reading for pleasure on an average day has fallen by 40% in 20 years, to about one in six. When you only get a few books a year, a dud costs you more than it used to.

The tools meant to fix this haven't kept up. Goodreads has over 150 million members and is still the default, but since Amazon bought it in 2013 the product has barely moved: whole-star ratings, no dark mode and an iOS app sitting around 3 stars. Sam Parr summed it up when he said he wishes he owned Goodreads. The reviews and community are great. Search, lists and AI are wide open.

Here's the kicker. Most keen readers already have years of taste data sitting in their Goodreads history: every five-star, every abandoned book, every grumpy three-star review. That's an incredibly rich signal, and almost nobody uses it properly. Readers either start from scratch on a new app or get served the same bestseller as everyone else.

✅ Solution

Margins, an AI book discovery app that turns your reading history into a personal librarian.

• Import your reading life in one click. Pull in a Goodreads or StoryGraph export with ratings, reviews, shelves and abandoned books. Margins builds a taste profile on day one, so there's no cold start.
• Chat with a librarian that actually knows you. Ask for "a business biography as entertaining as Shoe Dog, but under 300 pages" or "something like Project Hail Mary, but less science-heavy". Every pick comes with a short reason it fits, grounded in books you've already rated.
• Close the loop after every read. Finish a book, tell Margins in a sentence what worked and what didn't, and the next recommendation gets sharper. The feedback is the product.
• Make it social. Follow friends and favourite reviewers, find "taste twins" whose ratings overlap with yours, and turn recommendations into shared lists for book clubs, vacations or gifting.
• Buy in one tap. Every recommendation links out to Bookshop.org, Kindle, Libby or Audible, so discovery flows straight into reading (and revenue).

The wedge is deliberately narrow: nail "what should I read next?" for heavy readers who already track. Tracking, reviews and community come along for the ride.

📊 Key Numbers

Market size

• US publishers generated $33.4 billion in 2025, with consumer (trade) books making up $21.7 billion of that.
• US print unit sales hit 762.4 million copies in 2025, before you count ebooks and audio.
• The tracking audience is already huge: Goodreads has 150 million members, and StoryGraph passed 5 million signups in January 2026 as the leading independent alternative. Readers will switch.