Zube - Project management for developers.

Lago Billing - Open-source alternative to Stripe Billing and Chargebee

Nifty - Manage projects, work, and communications in one place.

Metronome - Metronome helps software companies launch, iterate, and scale their usage-based business models, with billing infrastructure that works at any size and stage.

Client Portal - A client-friendly way to keep your projects organised

Chargebee - Chargebee lets you manage subscriptions and payments at scale, handle custom recurring billing scenarios, reduce subscription churn and simplify accounting.