Invoice Ninja

Invoice Ninja is an open-source invoicing and billing platform built for freelancers and small businesses. It launched in 2014 and now serves over 200,000 businesses worldwide. The tool directly solves the problem of unpaid invoices by letting users send, track, and collect payments in one place.

Features

• Multi-Gateway Payment Processing: Supports dozens of global payment gateways, including Stripe and PayPal. Clients can pay invoices in one click directly from the emailed invoice link.
• Recurring Invoices & Auto-Billing: Users can set up automatic recurring invoices on custom schedules. The system charges saved client payment methods without manual action each cycle.
• Expense & Vendor Tracking: Users log, categorize, and re-invoice expenses directly inside the platform. It also syncs bank, credit card, and PayPal transactions automatically.
• Project & Time Tracking: Built-in task and project tools let users log billable hours. Those hours convert directly into line items on client invoices.
• Self-Hosting & White-Label Option: The full source code is available on GitHub under a source-available license. A $40/year white-label add-on removes Invoice Ninja branding from all client-facing pages.

Use Cases

• For Freelancers: Send branded invoices, track billable hours, and accept global payments without needing accounting software.
• For Small Agencies: Manage multiple clients, assign projects to tasks, and convert tracked work hours into accurate client bills.
• For Privacy-Focused Businesses: Self-host the entire platform on a private server to keep all financial data under full internal control.
• For Service Businesses with Repeat Clients: Automate recurring billing cycles and reduce manual invoice creation for subscription-style or retainer work.

Invoice Ninja is a feature-rich, open-source invoicing tool that suits freelancers and small teams needing payment collection without high software costs. Its self-hosting option and white-label support give it more flexibility than most entry-level invoicing tools.