The VCA open-source project is led by Christian Doppler Laboratory ATHENA, University of Klagenfurt, Austria. The primary objective of VCA is to become the best spatial and temporal complexity predictor for every video/ video segment which aids in predicting encoding parameters for applications like online per-title encoding. VCA is available as an open-source library, published under the GPLv3 license. The source code of VCA is available here. VCA leverages x86 SIMD and multi-threading optimizations for effective performance. While VCA is primarily designed as a video complexity analyzer library, a command-line executable is provided to facilitate testing and development. We expect VCA to be utilized in many leading video encoding solutions in the coming years.