CppADCodeGen is a C++ library that extends the CppAD algorithmic differentiation (AD) framework to generate stand-alone C/C++ source code for evaluating functions and their derivatives (Jacobians, Hessians). It converts a CppAD operation tape into a computation graph and then emits efficient, compilable code via multiple backends: C, LaTeX, MathML, and DOT. The generated code can be compiled into dynamic libraries at runtime (Linux) or JIT-compiled using Clang/LLVM, enabling high-performance derivative computation in production environments. The library also includes a suite of algorithms for differential-algebraic equation (DAE) index reduction (Pantelides, Soares-Secchi, dummy derivatives), pattern detection for loop optimization, sparse derivative computation, and a thread pool for parallel evaluation. It is heavily used in scientific computing, simulation, and optimization contexts (e.g., chemical engineering models). The codebase is a header-only template library with optional runtime compilation components, distributed under dual EPL-1.0 and GPL-3.0 licenses.