StructEval: Benchmarking LLMs' Capabilities to Generate Structural Outputs

As Large Language Models (LLMs) become integral to software development workflows, their ability to generate structured outputs has become critically important. We introduce StructEval, a comprehensive benchmark for evaluating LLMs' capabilities in producing both non-renderable (JSON, YAML, CSV) and renderable (HTML, React, SVG) structured formats. Unlike prior benchmarks, StructEval systematically evaluates structural fidelity across diverse formats through two paradigms: 1) generation tasks, producing structured output from natural language prompts, and 2) conversion tasks, translating between structured formats. Our benchmark encompasses 18 formats and 44 types of task, with novel metrics for format adherence and structural correctness. Results reveal significant performance gaps, even state-of-the-art models like o1-mini achieve only 75.58 average score, with open-source alternatives lagging approximately 10 points behind. We find generation tasks more challenging than conversion tasks, and producing correct visual content more difficult than generating text-only structures.

@article{yang2025_2505.20139,
  title={ StructEval: Benchmarking LLMs' Capabilities to Generate Structural Outputs },
  author={ Jialin Yang and Dongfu Jiang and Lipeng He and Sherman Siu and Yuxuan Zhang and Disen Liao and Zhuofeng Li and Huaye Zeng and Yiming Jia and Haozhe Wang and Benjamin Schneider and Chi Ruan and Wentao Ma and Zhiheng Lyu and Yifei Wang and Yi Lu and Quy Duc Do and Ziyan Jiang and Ping Nie and Wenhu Chen },
  journal={arXiv preprint arXiv:2505.20139},
  year={ 2025 }
}