SOTOPIA -S4: a user-friendly system for flexible, customizable, and large-scale social simulation (2025)

Abstract: Social simulation through large language model (LLM) agents is a promising approach to explore and validate social science hypotheses.We present SOTOPIA-S4, a fast, flexible, and scalable social simulation system that addresses the technical barriers of current frameworks while enabling practitioners to generate realistic, multi-turn and multi-party interactions with customizable evaluation metrics for hypothesis testing. SOTOPIA-S4 comes as a pip package that contains a simulation engine, an API server with flexible RESTful APIs for simulation management, and a web interface that enables both technical and non-technical users to design, run, and analyze simulations without programming. We demonstrate the usefulness of SOTOPIA-S4 with two use cases involving dyadic hiring negotiation scenarios and multi-party planning scenarios.

## introduction social simulation has emerged as a powerful tool for understanding human behavior and social dynamics @xcite @xcite . with the advancement of role-playing abilities of large language models (llms), we can now simulate realistic social interactions at scale @xcite @xcite . however, existing frameworks require significant technical expertise to run and evaluate large-scale simulations efficiently @xcite @xcite . we present sotopia-s 4 (simple social simulation system), a system designed that enables practitioners without extensive technical backgrounds to: (1) design social simulations through natural language specifications, eliminating the need for * equal contributors. sotopia-s 4 's architecture separates core simulation logic from the user interface, allowing practitioners to focus on experimental design rather than implementation details. specifically, we offer sotopia-api, a fastapi-based protocol for simulation management. users can retrieve and upload characters, scenarios, evaluation metrics, and start scaled simulations through the api. besides the api, we also offer a web-based application for visualizing and editing scenarios, characters, and simulation results. on the backend, the simulation engine handles complex technical aspects like asynchronous execution, llm api management, and data persistence automatically, abstracting away the underlying complexities from the users. to showcase the flexibility and usability of sotopia-s 4 , we demonstrate two use cases. first, we use sotopia-s 4 to examine the effects of user personality in a hiring negotiation setting, by simulating multiple multi-turn dyadic interactions and evaluating the interaction outcomes. extending beyond dyadic interactions, we also show that sotopia-s 4 can be used to simulate multi-party scenarios, where agents can act simultaneously and make contingent offers to each other. furthermore, we stress test the system with a large group of agents to showcase its scalability. we release the code and a user guide at https: //github.com/sotopia-lab/sotopia , a website with documentation and examples at https: //demo.sotopia.world , and a video demo at https://youtu.be/dzq9tnqerks . of agent-based simulation in social sciences ( §2.1), yet differentiates itself from many existing agent simulation frameworks ( §2.2). ## simulation and evaluation overview in this section, we introduce the key components required to design and execute social simulations with sotopia-s 4 (figure 1 ). we describe the elements to configure a simulation task, explain our asynchronous interaction framework that enables realistic multi-party interactions, and present our automated evaluation capabilities. ## api and web ui as handling the simulation engine can be complex, sotopia-s 4 provides a flexible api and a user-friendly web ui enabling researchers to easily customize, run, and analyze simulations. ## sotopia-s 4 use cases to demonstrate the flexibility and utility of sotopia-s 4 , we present two use cases that showcase how researchers can leverage our system for investigating social science hypotheses and better understand llm agents' behavior. we also stress test the system with a large group of agents to showcase its scalability. ## conclusion in this paper, we present sotopia-s 4 , an easyto-use, flexible, and scalable social simulation system that enables diverse interactions and automatic evaluation. through its api and web interface, researchers can create, customize, and analyze social simulations, even without much programming experience. by lowering the barrier to simulate social phenomena at scale with llms, sotopia-s 4 opens new possibilities for understanding llm agent behavior and social science investigations and enables new research directions.