Invoice Ninja

Invoice Ninja is a source-available invoicing and billing application for small businesses and freelancers. It helps you create invoices and quotes, accept online payments, manage clients, and track work with projects and time entries.

Key Features

• Create and send invoices, quotes, and credit notes with customizable templates and branding
• Client portal for viewing invoices, making payments, and accessing documents
• Online payment integrations and payment reminders for due and overdue invoices
• Expense tracking plus basic business workflow around clients and items/products
• Projects and time tracking to bill hours and manage ongoing client work
• REST API for integrating invoicing and client data into other systems

Use Cases

• Freelancers generating professional invoices and accepting online payments
• Small businesses managing quotes, recurring invoices, and client communications
• Agencies tracking time and projects and converting work logs into invoices

Limitations and Considerations

• Source-available under the Elastic License rather than a permissive OSI license
• Some features (for example, white-labeling) may require a paid license

Invoice Ninja provides a comprehensive invoicing workflow with a client-facing portal and integrations, making it suitable for running billing and client management in-house. It’s a strong fit when you need both invoicing and time/project billing in a single system.