IBM Quantum Experience features a high-performance simulator for prototyping quantum circuits and algorithms, and exploring their performance under realistic device noise models. The simulator backend is called the ibmq_qasm_simulator. The underlying code is similar to the qasm_simulator found in Qiskit Aer.
As shown in the configuration information below, the simulator allows for up to 300 circuits per job, and natively supports a wide variety of unitary and non-unitary operations.
Note that unlike the real quantum devices, where jobs are put into a queue, IBM Quantum Experience is able to dynamically create multiple instances of the OpenQASM simulator to meet demand; under nominal workloads there is never a wait to run on the ibmq_qasm_simulator.
Simulator timeout limit
To prevent the simulator from processing jobs that would otherwise not finish processing in a reasonable amount of time, jobs sent to the ibmq_qasm_simulator are limited to run times under 10,000 seconds (~2.75 hours).