head to head · open source
opa vs Harden-Windows-Security
opa has 12,425 GitHub stars, 1,706 forks, 310 open issues and last shipped yesterday. Harden-Windows-Security has 4,831 stars, 348 forks, 5 open issues and last shipped 2 days ago. opa leads on adoption by 157% (12,425 vs 4,831 stars). opa is written in Go under Apache-2.0; Harden-Windows-Security is written in C# under MIT. opa has attracted 14% as many forks as stars, Harden-Windows-Security 7%. opa was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (compliance), 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
| opa | Harden-Windows-Security | |
|---|---|---|
| GitHub stars | ★ 12K | ★ 4.8K |
| License | Apache-2.0 | MIT |
| Written in | Go | C# |
| Last push | 2026-11-04 | 2026-11-03 |
| Forks | ⑂ 1.7K | ⑂ 348 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick opa if
- You weight community size — 12K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Go
- You value the larger contributor base for long-term maintenance
pick Harden-Windows-Security if
- You want the Harden-Windows-Security feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches C#
- You evaluated both and Harden-Windows-Security fits your workflow better
About opa
Open Policy Agent Open Policy Agent (OPA) is an open source, general purpose policy engine that enables unified, context aware policy enforcement across the entire stack. OPA is proud to be a graduated project in the Cloud Native Computing Foundation (CNCF) landscape. For details read the CNCF announcement. Get started with OPA Write your first Rego policy with the Rego Playground or use it to share your work with others for feedback and support. Have a look at the Access Control examples if you're not sure where to start. Install the VS Code extension to get started locally with live diagnostics, debugging and…
About Harden-Windows-Security
Harden Windows Security A New Threat to Malware Harden Windows Safely, Securely, Only With Official Microsoft Methods How To Use Related Trust Support Security Recommendations Resources License Wiki Basic FAQs Roadmap Donation [!IMPORTANT]\ Here are Quick Access Points to Important Sections of this Repository Harden System Security App AppControl Manager App Application Control for Business Resources [!NOTE]\ This repository only uses the features that have already been implemented by Microsoft in Windows OS to fine tune it towards the highest security and locked down state, without relying on any 3rd party…
read the full Harden-Windows-Security overview →
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Frequently asked questions
Is opa or Harden-Windows-Security more popular?
opa has 12,425 GitHub stars and Harden-Windows-Security has 4,831. opa has the larger community by that measure.
Are opa and Harden-Windows-Security free?
Both are open source. opa is licensed under Apache-2.0 and Harden-Windows-Security under MIT. Neither carries a licence fee.
What is the difference between opa and Harden-Windows-Security?
opa is written in Go and Harden-Windows-Security in C#. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, opa or Harden-Windows-Security?
Choose opa if you want the larger community (12,425 stars) or its Apache-2.0 licence terms. Choose Harden-Windows-Security if its feature set, stack or MIT licence fits better. Both are self-hostable.