  Quantum resource analysis is crucial for designing quantum circuits as well
as assessing the viability of arbitrary (error-corrected) quantum computations.
To this end, we introduce QUANTIFY, which is an open-source framework for the
quantitative analysis of quantum circuits. It is based on Google Cirq and is
developed with Clifford+T circuits in mind, and it includes the necessary
methods to handle Toffoli+H and more generalised controlled quantum gates, too.
Key features of QUANTIFY include: (1) analysis and optimisation methods which
are compatible with the surface code, (2) choice between different automated
(mixed polarity) Toffoli gate decompositions, (3) semi-automatic quantum
circuit rewriting and quantum gate insertion methods that take into account
known gate commutation rules, and (4) novel optimiser types that can be
combined with different verification methods (e.g. truth table or circuit
invariants like number of wires). For benchmarking purposes QUANTIFY includes
quantum memory and quantum arithmetic circuits. Experimental results show that
the framework's performance scales to circuits with thousands of qubits.
