Back to catalog
Invoice Ninja
AGPL-3.0Invoice Ninja is an open-source, self-hosted invoicing and billing platform that replaces single-rail tools with multi-gateway client management.
Open-source alternative to — compare it against:
Overview
PayPal Invoicing tethers billing workflows to a single payment processor, charges fixed transaction cuts, and stores client records on proprietary servers. Invoice Ninja decouples billing from specific payment rails by running as a self-hosted platform connected to dozens of gateways simultaneously. Small agencies and operations leads gain unified dashboards, customizable client portals, and complete ownership over invoice histories without recurring seat fees.
Why Invoice Ninja instead of PayPal
PayPal Invoicing operates as a payment processor feature, enforcing vendor lock-in. Transactions must clear PayPal's rail and incur standard merchant cuts. Invoice Ninja shifts billing into an independent orchestration layer. Teams can connect multiple gateways side by side—offering credit cards via Stripe, bank debits through Mollie, or direct PayPal checkout—while managing numbering and retainers from one interface. When an agency switches merchant providers to negotiate lower rates, client records remain untouched.
Where PayPal holds an advantage is operational convenience. Setup requires only a merchant account and zero server maintenance. Invoice Ninja demands infrastructure ownership: self-hosting requires maintaining a PHP runtime, a MariaDB database, Redis queues, and background cron workers. Teams must also configure reverse proxies and transactional email routing. For agencies managing recurring retainers across regions, that operational effort eliminates per-seat SaaS fees and unlocks multi-gateway routing.
What it does well
- Multi-gateway payment routing: connects multiple processors simultaneously, letting clients choose between credit cards, bank debits, or digital wallets.
- Self-service client portal: gives clients a dashboard to review unpaid invoices, approve quotes, track tasks, and download PDF receipts.
- Automated recurring billing: schedules retainer invoices, sends payment reminders, and charges stored payment methods automatically.
- Billable time tracking: logs contractor hours against milestones and converts tracked time directly into itemized invoice lines with one click.
- Multi-company tenancy: enables agencies running several subsidiaries or brands to manage separate client directories and invoice numbering in one installation.
- Multi-platform client apps: offers native desktop and mobile apps across Linux, macOS, Windows, Android, and iOS for tracking invoices from any workstation.
