Tributary is a non-custodial recurring payment protocol built on the Solana blockchain. It enables users to manage subscriptions, milestone payments, and pay-as-you-go billing through token delegation. With Tributary, users can sign once and enjoy automatic payments, while also having the ability to verify transactions anywhere. The service is live on the Solana mainnet, providing a secure and efficient way to handle recurring payments without needing extensive Solana coding knowledge.