Marc Seitz, co-founder of Papermark, built an open source DocSend alternative in a single weekend in 2023 and has bootstrapped it to $3M in ARR with 3,000 paying customers. He broke $1M in September 2025 and $2M just 4 months later, adds about 100 signups a day from a free plan, and runs the Munich company 50/50 with his wife with zero outside funding. He breaks down how 8,900 GitHub stars and 60,000 teams turn into revenue, why open source contributions are fading in the age of AI coding tools, and whether he would sell if Dropbox offered $30M in cash.

Topics: bootstrapped SaaS, open source software, commercial open source, virtual data rooms, document sharing, DocSend alternative, product-led growth, freemium, building in public, husband and wife co-founders.