Aliro Simulator is a modular quantum network simulator designed to model quantum networks from individual optical components to large-scale heterogeneous networks. The tool enables organizations to design, simulate, and evaluate quantum network implementations before purchasing or deploying hardware. The simulator supports discrete event simulation, multiple state computation backends, generic quantum and classical device components, optical components, noise models, and networking concept abstractions. Users can construct and simulate quantum networks at full scale down to low levels of abstraction. The platform includes a visualization tool that allows users to graphically investigate node-level performance of network designs and protocols. Organizations can assess network implementation requirements, create performance estimates for data rates and fidelity, and make informed decisions about cost and performance trade-offs. Users can evaluate the performance and interoperability of competing hardware modalities and devices, develop and test protocols with desired network configurations, and benchmark applications. The simulator enables determination of proof of value for quantum network implementations prior to hardware and software purchases. The tool supports assessment of application requirements, realistic performance estimates for network designs, evaluation of hardware device interoperability, protocol development and testing, and use case viability analysis for planned network implementations.