head to head · open source
Invoice Ninja vs Polar
Invoice Ninja has 10,464 GitHub stars, 2,793 forks, 945 open issues and last shipped yesterday. Polar has 10,454 stars, 811 forks, 141 open issues and last shipped yesterday. Invoice Ninja leads on adoption by 0% (10,464 vs 10,454 stars). Invoice Ninja is written in PHP under a custom or non-standard licence; Polar is written in Python under Apache-2.0. Invoice Ninja has attracted 27% as many forks as stars, Polar 8%. 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
| Invoice Ninja | Polar | |
|---|---|---|
| GitHub stars | ★ 10K | ★ 10K |
| License | Custom / other | Apache-2.0 |
| Written in | PHP | Python |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 2.8K | ⑂ 811 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Invoice Ninja if
- You weight community size — 10K stars and counting
- You want the Custom / other license terms
- Your stack matches PHP
- You value the larger contributor base for long-term maintenance
pick Polar if
- You want the Polar feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Python
- You evaluated both and Polar fits your workflow better
About Invoice Ninja
Invoice Ninja 5 Invoice Ninja Version 5 is here! We've taken the best parts of version 4 and added the most requested features to create an invoicing application like no other. Check the Invoice Ninja YouTube Channel to get up to speed, or try the Demo now. Choose your setup Hosted: Our hosted version is a Software as a Service (SaaS) solution. You're up and running in under 5 minutes, with no need to worry about hosting or server infrastructure. Self Hosted: For those who prefer to manage their own hosting and server infrastructure. This version gives you full control and flexibility. All Pro and Enterprise…
read the full Invoice Ninja overview →
About Polar
Website • Docs • API Reference Polar: A billing platform for the intelligence era Turn usage into revenue. Polar is the financial layer for a new generation of intelligent software, built for AI startups that need to charge for tokens, agents, and compute without building billing infrastructure from scratch. Ship any pricing model in an afternoon. Usage billing, subscriptions, seats, credits, trials, and discounts. Compose them however your product charges. Meter what matters. Bill tokens, API calls, agent runs, GPU seconds, and storage with precision down to the event. Checkouts that convert , realtime metrics…
read the full Polar overview →
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Frequently asked questions
Is Invoice Ninja or Polar more popular?
Invoice Ninja has 10,464 GitHub stars and Polar has 10,454. Invoice Ninja has the larger community by that measure.
Are Invoice Ninja and Polar free?
Both are open source. Invoice Ninja has no licence declared in this registry, and Polar is licensed under Apache-2.0. Both are free to self-host.
What is the difference between Invoice Ninja and Polar?
Invoice Ninja is written in PHP and Polar in Python. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Invoice Ninja or Polar?
Choose Invoice Ninja if you want the larger community (10,464 stars) or its Custom / other licence terms. Choose Polar if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.