GLM Model API gives developers and enterprises programmatic access to Z.ai's GLM family of large language models through a single application-programming-interface surface. The published documentation describes model selection, streaming responses, function calling, vision and reasoning models, fine-tuning, rate limits, and per-token pricing, with API keys issued from a developer console.

The offering evolved from the company's earlier BigModel open platform, which exposed ChatGLM and later GLM models to Chinese enterprise customers. Z.ai now publishes pricing for flagship and Flash model tiers and sells subscriptions that bundle the same model access for coding workloads.