Bigcapital
Bigcapital is financial accounting with intelligent reporting for faster decision-making, an open-source alternative to Quickbooks, Xero, etc.
Lago
Open-source alternative to Stripe Billing and Chargebee it offers a modular architecture for metering and usage-based billing, at every stage of your company.
Crater
Crater helps you track expenses, and payments & create professional invoices & estimates.
InvoiceNinja
Invoice Ninja is the leading free, open-source online invoicing app for freelancers and businesses.
BTCPay
Start Accepting Bitcoin Payments With 0% Fees & No Third-party
Hyperswitch
An open-source payments switch written in Rust to make payments fast, reliable, and affordable.