Touch Grass had 40,000 preorders before Rhys Kentish worked out it would cost $20,000 a week to run
Touch Grass is a screen time app that keeps distracting apps locked until you go outside and photograph real grass. Developer Rhys Kentish posted an early prototype to Reddit and Hacker News, where it went viral; he opened preorders the same day and ended up with roughly 40,000. He then calculated that Google Vision's cloud API would cost about $20,000 a week at that scale, and rewrote the vision detection natively on-device over three sleepless days before launch.
What this means for indie developers：Price out per-call cloud APIs before going viral and move detection on-device early; a price-free preorder page also keeps sharing friction low.