InvoiceNinja

A fully bootstrapped invoicing platform serves small businesses that need straightforward billing, payment tracking, and expense management without unnecessary complexity. The founders built a reliable invoicing tool that simply works, offering both a free open-source edition and paid hosted plans to attract users at every stage of growth. The B2B subscription model now generates $43,000 per month—over $500,000 annually—proving that solving essential but unglamorous business problems can sustain a profitable company without outside funding. The product continues to grow through word of mouth and its active open-source community.