Open source tooling

Qiskit 2.0.0 was released on 31 March 2025. The release removed legacy APIs (the .c_if() method, the qobj module, BackendV1 and the Pulse package), added a C API for sparse observables, the SDK's first public C interface, and reported a 2× speedup in circuit construction over v1.3 from its Rust core. Qiskit is the SDK the site's own transpiler pipeline targets; the research wing's Benchpress entry (claim C14) is IBM's pytest based cross SDK benchmark built around it.

The OpenQASM specification's latest release is v3.1.0 (15 May 2024). OpenQASM 3 is the intermediate representation higher level compilers use to talk to hardware, adding classical feed forward control flow based on measurement outcomes and timing constructs (including 'stretch' for deferred timing resolution). The transpiler on this site parses OpenQASM 2.0 and 3.0; the Circuit Lab exports 2.0.

CUDA-Q is NVIDIA's open source (Apache-2.0) platform for hybrid quantum classical programs in C++ and Python, with a unified model for CPUs, GPUs and QPUs working together, the toolchain for the hybrid systems engineer role in the careers section.

Gidney's Stim simulates stabilizer circuits using an inverse tableau representation, SIMD optimized data layouts and Pauli frame propagation. The paper reports analyzing a distance 100 surface code circuit (20,000 qubits, 8 million gates, 1 million measurements) in 15 seconds and then sampling full shots at 1 kHz. It is the workhorse behind the below threshold experiments on the hardware scoreboard.

All of the major frameworks are Apache-2.0 licensed. GitHub stars on the check date: Qiskit 7,731; Cirq (Google) 5,052; PennyLane (Xanadu, automatic differentiation for hybrid quantum classical programs) 3,431; CUDA-Q 1,118; Stim 811; the OpenQASM specification 1,500. Stars measure attention, not quality, a dated proxy, nothing more.