  Rational Tracer (Ratracer) is a tool to simplify complicated arithmetic
expressions using modular arithmetics and rational function reconstruction,
with the main idea of separating the construction of expressions (via tracing,
i.e. recording the list of operations) and their subsequent evaluation during
rational reconstruction. Ratracer can simplify arithmetic expressions (provided
as text files), solutions of linear equation systems (specifically targeting
Integration-by-Parts (IBP) relations between Feynman integrals), and even more
generally: arbitrary sequences of rational operations, defined in C++ using the
provided library ratracer.h. Any of these can also be automatically expanded
into series prior to reconstruction. This paper describes the usage of Ratracer
specifically focusing on IBP reduction, and demonstrates its performance
benefits by comparing with Kira+FireFly and Fire6. Specifically, Ratracer
achieves a typical ~10x probe time and ~5x overall time speedup over
Kira+FireFly, and even higher if only a few terms in $\varepsilon$ need to be
reconstructed.
