If you are looking for RefProp 9.1 for professional or academic use, there are three primary paths to consider before looking for "free" downloads that may contain malware. 1. Check Institutional Licenses
You can purchase the latest version directly from NIST. While 9.1 is older, purchasing the current version often grants you the most up-to-date data, which is more reliable for modern engineering applications. 3. The Mini-RefProp (Free Version) NIST does offer a "Mini-RefProp" for free. refprop 91 free
If you cannot afford a RefProp license, there are powerful, open-source alternatives that offer similar accuracy for common fluids. ⚙️ CoolProp (Recommended) CoolProp is the best free alternative to RefProp. Completely free for all users. If you are looking for RefProp 9
A free, open-source chemical process simulator. It includes its own property packages and can integrate with CoolProp to provide RefProp-like functionality within a full plant simulation environment. A Note on "Free" Downloads While 9
Excellent for students learning the interface or testing basic thermodynamic cycles. Legitimate Free Alternatives to RefProp
Works with Python, C++, Excel, MATLAB, and Mathcad.
Fees fund the continued updates of fluid property libraries. How to Get RefProp (The Right Way)