Open-source alternatives to Killbill

Akaunting is a modular business enterprise resource planning system and self-hosted accounting software. It provides a comprehensive platform for small business financial management, centering on a double-entry bookkeeping system with a general ledger and chart of accounts. The platform is designed for extensibility through a module-based architecture and a dedicated marketplace for procuring third-party applications. It supports multi-tenant data isolation and utilizes role-based access control to manage granular user permissions. Its capability surface covers a wide range of business opera

Vendure is a Node.js e-commerce engine and headless commerce framework built with NestJS and TypeScript. It serves as a multi-channel commerce platform that manages product catalogs, orders, and customers via a strongly typed GraphQL API. The platform is distinguished by its highly extensible architecture, featuring a customizable administrative dashboard where developers can inject custom React components and entity views. It supports multi-channel commerce, allowing the isolation of products, currencies, and regional catalogs from a single unified backend. The engine covers a broad range o

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

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

aimeos-laravel is a comprehensive e-commerce framework for building online stores and B2B marketplaces using the Laravel PHP framework. It functions as a digital storefront engine and multi-tenant e-commerce platform, providing the core logic for managing product catalogs, shopping baskets, and payment processing. The project is distinguished by its ability to support complex business models, including multi-vendor marketplaces and professional B2B commerce suites with tiered pricing and procurement workflows. It also provides a headless commerce API, allowing store data and business logic to

yii2_fecshop is a comprehensive B2C e-commerce platform and CMS built on the Yii2 PHP framework. It functions as a headless commerce API and an international storefront solution, supporting both single-vendor stores and multi-vendor marketplaces where independent merchants can manage their own products and orders. The system is distinguished by a multi-entry point architecture that separates administrative, web, mobile, and API interfaces while sharing a common service layer. It provides high extensibility through configuration-driven service replacement, event-driven functional extensions, a

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

Idurar is an integrated system combining Customer Relationship Management and Enterprise Resource Planning. It functions as a headless business API that generates secure REST endpoints and administrative panels from configuration files to connect business logic with external applications. The platform supports multi-tenant SaaS management, isolating data and configurations for multiple companies or branches within a single installation. It is designed for international business accounting, featuring a multi-currency financial engine that processes transactions and manages regional tax rules a

WooCommerce is a comprehensive eCommerce framework for WordPress that transforms websites into fully functional online stores for physical and digital goods. It serves as a digital storefront manager for product catalogs, inventory, and customer orders across retail and wholesale business models. The system functions as a payment gateway integrator, connecting shops to diverse processors for credit cards, digital wallets, and subscriptions. It also operates as an order fulfillment system for calculating shipping rates, generating labels, and coordinating delivery via third-party couriers, whi

CRMEB is a comprehensive e-commerce platform built on ThinkPHP 6, designed as a headless system that delivers standardized APIs to various frontend clients. It provides a unified backend to synchronize product catalogs, orders, and customer data across web browsers, mobile applications, and mini-programs. The platform supports diverse commerce models, including multi-vendor marketplaces where independent merchants manage their own stores, centralized chain store networks, and social commerce frameworks featuring affiliate distribution and community group buying. It also integrates specialized

Tigshop is a multi-tenant e-commerce framework designed to support single-merchant, multi-merchant, and cross-border retail configurations. It functions as a B2B2C marketplace platform that connects suppliers, store owners, and customers through integrated storefronts and vendor portals. The system is distinguished by an automated revenue splitting engine that divides transaction payments between platforms, merchants, and suppliers based on defined service fee rules. It includes a tiered affiliate distribution system for tracking multi-level commissions and an omnichannel retail manager that

TastyIgniter is a comprehensive restaurant management system and digital ordering engine. Built as a modular application framework, it provides the tools necessary to operate online food ordering, table reservation systems, and multi-vendor e-commerce platforms. The platform is designed to handle complex restaurant operations, including multi-location networking and multi-vendor marketplace management. It distinguishes itself through specialized restaurant automation, such as coordinating guest limits and time slots for bookings, managing ingredient and allergen catalogs, and implementing mul

InsForge is a backend-as-a-service platform that provides an integrated suite of tools for managing relational databases, identity provision, object storage, and serverless compute. It functions as an open-source identity provider and a PostgreSQL database manager featuring integrated vector storage and row-level security. The platform serves as an LLM orchestration gateway, offering a unified endpoint to route requests across various AI providers through an OpenAI-compatible interface. It enables AI-driven application generation and connects AI agents to backend resources using a standardize

Big Capital is a cloud accounting management system designed to track assets, liabilities, and equity through a digital ledger. It provides a multi-tenant organizational framework that supports multi-branch tracking and regional currency settings. The system distinguishes itself through integrated bank feed management, utilizing secure token exchanges and webhook processing for automated transaction synchronization and rule-based categorization. It also features a multi-currency ledger that handles base currency conversions and specific currency codes. The platform covers comprehensive finan

GAM is a command-line tool for administering Google Workspace and Cloud Identity. It translates command-line arguments into structured API calls, enabling administrators to manage users, groups, organizational units, and domain settings across a Google Workspace environment. The tool handles authentication through OAuth2 flows, service accounts, and workload identity federation, and supports multi-tenant configurations for managing multiple domains or cloud projects from a single installation. GAM distinguishes itself through its batch processing and automation capabilities. It can process la

This project is a comprehensive starter kit for building subscription-based web applications using Next.js and TypeScript. It provides a structural foundation for developing software-as-a-service platforms, incorporating integrated user authentication, payment tiers, and multi-tenant organization management. The framework distinguishes itself with a dedicated multi-tenant application architecture that organizes users into teams and organizations with workspace switching. It includes a built-in monetization layer via Stripe subscription integration for managing pricing tiers and billing cycles

Crater is an open-source invoicing and expense tracking software designed for individuals and small businesses. It serves as a self-hosted billing platform that allows users to monitor the overall financial health of a business by recording professional services rendered and tracking outgoing costs. The system functions as a payment gateway integrator, connecting to third-party providers such as Stripe to process secure transactions for issued invoices. It provides specialized tools for freelance invoice management, including the generation of professional billing documents and cost estimates

This project is a modular e-commerce platform built on Ruby on Rails, designed to serve as a comprehensive engine for managing online retail operations. It provides the foundational infrastructure to handle complex product catalogs, customer order lifecycles, and global payment processing within a unified system. The platform distinguishes itself through a headless, API-first architecture that decouples backend commerce logic from custom frontend storefronts. It supports multi-tenant environments, allowing for the management of multiple independent retail storefronts or marketplaces from a si

Medusa is a headless commerce engine designed as a modular, API-first platform for building custom digital storefronts and business applications. Its architecture is built on a decoupled system where core business logic is encapsulated into independent, swappable modules that communicate through defined interfaces, allowing developers to incrementally adopt or replace components to fit specific operational needs. The platform distinguishes itself through a highly extensible design that supports complex commerce requirements, including multi-vendor marketplace operations, B2B purchasing workfl

Ever Gauzy is an integrated business management suite providing an ERP and CRM framework for professional services automation. It functions as a multi-tenant SaaS platform that combines time tracking, billing, and human resource management into a unified system. The project is distinguished by its headless architecture, utilizing a REST and GraphQL API gateway to expose business operations. It features a Model Context Protocol server that allows AI assistants to interact with system data and execute functional tools for automated business workflows. The platform covers a broad operational su

Gauzy is an open business management platform and multi-tenant enterprise resource planning system. It provides a modular business framework designed to manage core organizational operations through a unified web interface or as a headless business API. The platform is distinguished by its integration with the Model Context Protocol, allowing it to act as a server that exposes business data and system functions as tools for AI assistants. It utilizes a dynamic plugin architecture and a dedicated marketplace to extend core business entities and services. The system covers a broad range of ope

Lunar is a modular PHP e-commerce framework and headless commerce engine designed to manage the backend logic and data models of an online store. It provides a decoupled infrastructure that separates business logic from the presentation layer, allowing for the orchestration of digital storefronts via an API. The system is distinguished by its headless-first approach and a dedicated toolkit for building customized administration interfaces using pre-made components and widgets. It supports complex global operations through a multilingual commerce system that handles regional storefront configu

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

Geekai is a multi-model AI platform and SaaS framework designed to deploy and manage AI agents and multimodal models through a unified interface. It serves as a multimodal AI gateway, providing centralized access to large language models and generative tools for text, image, audio, and video production. The project functions as an AI agent orchestrator, allowing for the definition of specialized personas and the import of external workflows and knowledge bases. It distinguishes itself by providing a complete commercial service layer, including credit-based billing, subscription management, an

Camunda is a business process automation platform and orchestration tool used to model, deploy, and monitor automated workflows and human-centric tasks. It features a BPMN workflow engine for executing processes based on the BPMN 2.0 standard and a DMN decision engine for automating business logic and rule evaluation. The platform is designed for flexibility through an embedded workflow library that allows the engine to be integrated directly into custom applications. It supports multi-tenant workflow management, enabling the secure separation of process definitions and instance data for mult

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

This project is a multi-gateway payment SDK that provides a unified API and abstraction layer for integrating multiple payment providers. It maps high-level payment operations to provider-specific API calls and standardizes diverse outputs through a unified response normalization system. The SDK supports multi-tenant configuration, allowing a single runtime instance to isolate credentials and settings for different business accounts. It features a plugin-based architecture that enables the addition of custom payment gateways through abstract class implementations. The capability surface cove