head to head · open source
Polar vs Invoice Ninja
Polar has 10,270 GitHub stars, 787 forks, 141 open issues and last shipped yesterday. Invoice Ninja has 10,086 stars, 2,707 forks, 945 open issues and last shipped yesterday. Polar leads on adoption by 2% (10,270 vs 10,086 stars). Polar is written in Python under Apache-2.0; Invoice Ninja is written in PHP under a custom or non-standard licence. Polar has attracted 8% as many forks as stars, Invoice Ninja 27%. Polar was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (payments), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Polar | Invoice Ninja | |
|---|---|---|
| GitHub stars | ★ 10K | ★ 10K |
| License | Apache-2.0 | Custom / other |
| Written in | Python | PHP |
| Last push | 2026-09-17 | 2026-09-17 |
| Forks | ⑂ 787 | ⑂ 2.7K |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Polar if
- You weight community size — 10K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick Invoice Ninja if
- You want the Invoice Ninja feature set and don't need the biggest community
- You prefer the Custom / other license terms
- Your stack matches PHP
- You evaluated both and Invoice Ninja fits your workflow better
About Polar
Polar is an open source billing platform and payment infrastructure project for digital products, SaaS applications, and AI workloads. It is written in Python, licensed under Apache 2.0, and built around FastAPI, Next.js, React, and Turborepo. The project positions itself as a financial layer for software that needs to charge for tokens, agents, compute, subscriptions, and usage based models.
read the full Polar overview →
About Invoice Ninja
Invoice Ninja is a source available invoice, quote, project, and time tracking application built with Laravel and PHP. It lives in the Laravel ecosystem and is positioned as an open alternative to QuickBooks, Xero, and FreshBooks. The project provides a web application, API, desktop clients, and mobile clients for businesses that need to bill clients and manage payment related work.
read the full Invoice Ninja overview →
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Frequently asked questions
Is Polar or Invoice Ninja more popular?
Polar has 10,270 GitHub stars and Invoice Ninja has 10,086. Polar has the larger community by that measure.
Are Polar and Invoice Ninja free?
Both are open source. Polar is licensed under Apache-2.0, and Invoice Ninja has no licence declared in this registry. Both are free to self-host.
What is the difference between Polar and Invoice Ninja?
Polar is written in Python and Invoice Ninja in PHP. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Polar or Invoice Ninja?
Choose Polar if you want the larger community (10,270 stars) or its Apache-2.0 licence terms. Choose Invoice Ninja if its feature set, stack or Custom / other licence fits better. Both are self-hostable.