While Native Instruments offers a the full version of Kontakt 5.7.3 is a paid professional product.
Kontakt 5.7.3 is a powerful engine that allows you to play, edit, and create sophisticated virtual instruments. While newer versions exist, 5.7.3 remains a "sweet spot" for many users due to its stability and compatibility with older operating systems and legacy sound libraries. It serves as both a host for high-end sample libraries and a deep sound-design tool for those building their own instruments.
Access to the underlying sample mapping, looping, and modulation routing for total creative control. Technical Specifications
Optimized for efficient RAM usage and multi-core processor support.
Allows for complex instruments with custom user interfaces and realistic performance behaviors (like legato or round-robins).
Runs licensed libraries from official partners but will only play unlicensed or user-created libraries in "Demo Mode" for 15 minutes.