Bigcapital is an open-source financial accounting and inventory management system designed for small and medium businesses seeking full control over their financial data. It replaces proprietary tools like QuickBooks and Xero with a transparent, self-hostable platform built on double-entry accounting principles. The system automates bookkeeping tasks, generates real-time financial reports, and supports multi-currency transactions and inventory tracking—all while offering a cloud-hosted option or full self-hosting via Docker.
Built with TypeScript and deployed via Docker containers, Bigcapital provides a RESTful API for headless integration, supports role-based user permissions, and includes automated bank imports, recurring invoices, and real-time exchange rate conversions. It’s AGPL-licensed, community-driven, and integrates with Postman for API testing and Gitpod for instant development environments.
What You Get
- Double-Entry Accounting - Fully automated double-entry bookkeeping system with journal entries, ledgers, and trial balance generation to ensure accurate financial records.
- Inventory Tracking - Automatic stock level updates when items are purchased or sold, with smart reports showing inventory turnover and valuation.
- Multi-Currency Accounting - Handle transactions in any currency with real-time exchange rate conversions and automatic currency reconciliation.
- Automated Bank Import - Connect bank accounts to automatically import and categorize transactions, reducing manual data entry.
- Smart Financial Reports - Generate real-time profit & loss, balance sheets, cash flow statements, and advanced inventory reports without waiting for month-end closing.
- Role-Based User Permissions - Invite accountants or team members with granular access controls for users, roles, and financial data visibility.
- Headless API Integration - Integrate Bigcapital’s accounting engine into existing systems via a documented REST API with Postman collections for testing.
- Recurring Invoices & Estimates - Create and automate recurring sales and purchase invoices with customizable templates and payment tracking.
- Expense Accounting - Centralize all business expenses—from payroll to rent—with categorization, bill-to-customer options, and tax compliance support (GST/VAT).
- Multiple Branches & Warehouses - Track financials and inventory across multiple physical locations with dedicated branch and warehouse management.
Common Use Cases
- Running a small retail business - A shop owner uses Bigcapital to track inventory levels in real time, generate sales invoices, and reconcile bank transactions without paying for QuickBooks.
- Managing a multi-currency e-commerce business - An online seller in Europe and North America uses Bigcapital to handle USD, EUR, and GBP transactions with automatic exchange rate updates and tax reporting.
- Accountants serving SME clients - A CPA firm invites multiple clients into their Bigcapital instance with role-based access to review books, run reports, and collaborate without data exports.
- Scaling a business with multiple locations - A franchise operator tracks sales, inventory, and expenses across 5 branches using Bigcapital’s multi-branch and multi-warehouse features.
- Developers building financial tools - A SaaS founder integrates Bigcapital’s API to power accounting features in their own business software without licensing proprietary systems.
Under The Hood
Architecture
- Monorepo structure using Lerna with well-defined modules for server, webapp, and shared components, enabling independent development and versioning
- Server built on NestJS with clean separation of controllers, services, and repositories via dependency injection
- Event-driven design using domain events and message queues to decouple core business logic from external integrations
- Multi-tenant database strategy with dynamic naming and centralized configuration for scalable SaaS deployment
- External services abstracted into dedicated packages with dependency injection for testability and modularity
- Docker-based environments with clear service boundaries and volume isolation for production and development
Tech Stack
- NestJS backend with TypeScript, leveraging BullMQ for job processing and Redis for caching and session management
- MySQL/MariaDB with Knex.js for migrations and tenant-aware query execution
- Redis used for caching, session storage, and job queue persistence
- Monorepo managed by Lerna and pnpm, with modular packages for server, webapp, PDF templates, and SDK
- Dockerized deployment with Envoy as reverse proxy, Gotenberg for PDF generation, and automated service orchestration
- CI/CD and development tooling including Playwright, Husky, Vercel, and Gitpod for seamless workflows
Code Quality
- Extensive end-to-end test suite covering authentication, APIs, and UI interactions with realistic data generation
- Consistent use of custom test utilities to standardize context and authorization across test suites
- Clear separation between frontend utilities and backend logic, with focused, isolated test files per domain
- Robust error handling with appropriate HTTP status codes and structured responses
- Strong type safety and descriptive naming conventions throughout both frontend and backend codebases
- Comprehensive linting and testing infrastructure, though unit test coverage is less prominent than E2E
What Makes It Unique
- Native double-entry accounting engine with real-time ledger reconciliation embedded in the data model
- Dynamic account type system with hierarchical permissions and context-aware journal entry generation
- Unified financial data pipeline that synchronizes transactions into a single audit-trail graph with anomaly detection
- Client-facing dashboard with live balance simulation using in-memory ledger snapshots for instant scenario analysis
- Extensible cell-based data grid that renders accounting fields with live validation and auto-suggest
- Themeable financial UI using CSS custom properties and BEM-like scoping to ensure readability in dark mode