Gumroad has extended its open-source marketplace hackathon: submissions are due Sept 15, 2025 (11:59 PM ET). Finalist celebration will be held in New York in Winter 2025. Prize pool: $100,000 grand prize; $5,000 for highest GMV; $2,500 for most creative; ten $1,000 prizes. Build from the project’s MIT-licensed code. Open to individuals and teams worldwide.