Question: I need a system that can manage online payments, subscriptions, and custom payment schedules in one place.

One of the strongest is ROQ, a full-featured set of features for building multi-tenant, multi-role SaaS applications. It includes features like managed Postgres database deployment, secure frontend DB queries, user authentication with social logins, multi-tenancy and role-based access control, and Stripe integration for payment and subscription handling. ROQ also offers AI-assisted data modeling, so it's a good choice for developers who want to build secure, scalable, resilient SaaS apps as fast as possible.

Another good option is Inai, a full-stack payment platform that streamlines payment operations for global businesses. Inai integrates with many payment service providers, offering tools for detailed analysis, payment method orchestration, end-to-end reconciliation automation, and real-time payment monitoring. It supports more than 50 payment vendors and 300 local payment methods, so it's a good choice for e-commerce and subscription businesses trying to reduce payment failure rates and lower transaction costs.

For B2B needs, Slope offers a powerful payment and order-to-cash process automation platform. Slope offers credit card and ACH payments, guest checkout, milestone-based invoicing and custom payment schedules. It also offers embedded financing options and automates AR processes, so it's a good choice for B2B marketplaces, wholesalers and AP automation platforms. Slope offers enterprise-grade security and compliance, with flexible integration options for developers.