Fin provides a self-hosted, modular solution enabling AI agents and enterprise systems to seamlessly interact with various payment providers, such as Stripe and Paystack, through a single, unified API. It abstracts the complexities of individual payment gateways, allowing users to perform operations like initializing, verifying, and refunding payments, or managing customers and invoices without specific provider knowledge. This tool offers full control over deployments and credentials, supports optional API key authentication, and includes a metadata endpoint for discovering available payment tools and supported providers.