Open-Source Alternatives to Stripe

Crater is an invoicing and billing software system designed for creating professional invoices, estimates, and recurring billing schedules. It serves as a multi-entity accounting manager, allowing for the organization and separation of financial data and billing records across multiple different business organizations. The platform integrates payment gateway services to collect funds directly from customers and provides a secure client billing portal where customers can access account details and pay outstanding invoices. It also functions as an expense tracking application to log outgoing co

Crater is an open source invoicing software and multi-tenant accounting system. It serves as a financial management tool for creating professional invoices and estimates, tracking business expenses, and managing the financial records of several distinct business entities within a single instance. The platform integrates with payment processors to collect client payments automatically and provides a dedicated billing portal where customers can access their history and pay invoices online. It includes a template-based engine for generating PDF invoices and supports the automation of recurring s

Polar is a digital product monetization engine and subscription management system. It serves as a merchant of record platform that handles global sales tax and VAT compliance, providing the infrastructure for selling subscriptions and one-time digital goods via hosted checkouts and embedded payment flows. The project functions as an entitlement and access manager, automating the granting and restriction of digital benefits, license keys, and third-party platform roles. It includes a dedicated usage-based billing infrastructure that tracks customer activity through meters to apply aggregation

BTCPay Server is a non-custodial payment gateway and invoice manager designed for accepting Bitcoin and other cryptocurrencies directly into a private wallet. It serves as a self-hosted payment infrastructure that allows merchants to manage digital invoicing and storefronts without relying on third-party intermediaries. The system distinguishes itself through a non-custodial wallet architecture that ensures private keys remain on the user's own hardware or server. It integrates the Lightning Network for instant, low-cost transactions and provides a hardware-wallet signing bridge to secure tra

Invoice Ninja is a professional billing and invoicing platform designed for managing clients, projects, and financial records. It serves as a multi-currency billing system and time tracker available as both a cloud-based application and a self-hosted suite. The platform distinguishes itself through comprehensive support for regional taxes, diverse currency formats, and automated exchange rate updates. It includes dedicated cross-platform mobile and desktop applications to manage business data across different operating systems. The software covers the end-to-end financial lifecycle, includin

Kill Bill is a subscription billing platform and usage-based billing engine designed to manage recurring invoicing and automated payment collection. It functions as a multi-tenant billing infrastructure, providing isolated environments for different organizational entities through a dedicated API. The system is distinguished by a plugin-based extension framework that allows for the integration of third-party payment gateways and custom business logic. It includes a payment gateway orchestrator to handle transactions and refunds, as well as a revenue recognition system to allocate contract rev

Lago is an open-source billing platform designed for managing subscriptions, usage-based metering, and automated invoicing. It functions as a comprehensive system for defining pricing plans, tracking real-time consumption via a metering engine, and controlling feature entitlements based on active customer subscriptions. The platform differentiates itself through a dynamic billing engine that supports hybrid pricing models and a credit-based wallet system for managing prepaid funds. It includes specialized tools for multi-tenant entitlement mapping, allowing operators to tie specific product p

Omnipay is a PHP payment gateway library and integration framework that abstracts multiple payment service providers into a single, consistent API. It provides a standardized interface for managing payment lifecycles, allowing applications to execute authorizations, captures, and refunds across various financial services without rewriting code for each provider. The framework decouples application logic from provider-specific SDKs using an adapter pattern and data-transfer objects. This architecture ensures that raw gateway responses and HTTP requests are converted into predictable data shape

This project is a production-ready boilerplate designed for building subscription-based web applications. It provides a foundational framework for managing user identity, persistent relational data, and recurring billing cycles within a unified development environment. The platform distinguishes itself by integrating secure authentication workflows with automated subscription management. It utilizes a schema-first approach to database interactions, ensuring data consistency through type-safe queries and versioned migrations. By incorporating native support for payment provider APIs, the syste

This project is a Next.js SaaS starter kit and billing boilerplate designed for building subscription-based software services. It provides a pre-configured foundation that integrates a PostgreSQL database schema with Stripe to manage recurring billing, tiered pricing models, and customer payment portals. The implementation features a synchronization system that uses webhooks to mirror external product data and subscription states into a local relational database. It includes an authentication layer that links external identity providers to user accounts and manages secure session tracking. T

This project is a starter kit for building software as a service applications. It provides a foundational framework for developing scalable products with integrated subscription billing, user management, and automated cloud deployment pipelines. The core architecture centers on a multi-tenant application framework that isolates data and permissions between organizations using team workspaces and role-based access control. It utilizes a GraphQL API to ensure type-safe communication and data consistency between the frontend and backend. The system covers comprehensive identity and access manag

Wdc-saas-starter-kit is a full-stack Next.js and TypeScript web application boilerplate designed to launch subscription-based software products. It comes pre-configured with a relational database ORM layer, user authentication, role-based access control, and cloud object storage integrations for handling user-uploaded files and media. The starter kit features recurring subscription management and payment webhook processing through an integrated payment gateway to synchronize customer billing cycles, plan upgrades, and subscription statuses. It also includes multi-tenant team workspace archit