Pennybase is a minimalist Backend-as-a-Service implementation in under 1000 lines of Go code with zero external dependencies. It provides file-based CSV storage, REST API endpoints, authentication with session cookies, role-based access control, real-time updates via Server-Sent Events, and template rendering. Data is stored in human-readable CSV files with append-only versioning, making it suitable for simple applications that need basic backend functionality without the complexity of larger solutions like Firebase or Supabase.