GLM 4.5 Air (free) vs GLM 5.1

GLM-4.5-Air is the lightweight version of our newest flagship model family, designed specifically for agent-focused applications. Like GLM-4.5, it uses a Mixture-of-Experts (MoE) architecture, but with a smaller parameter footprint. GLM-4.5-Air also supports hybrid inference modes, including a "thinking mode" for deeper reasoning and tool usage, and a "non-thinking mode" for real-time interactions.

GLM-5.1 represents a major advance in coding ability, with especially notable improvements in tackling long-horizon tasks. Unlike earlier models designed for interactions lasting only minutes, GLM-5.1 can operate independently and continuously on a single task for over 8 hours, autonomously planning, executing, and refining its work throughout the process, ultimately producing complete, engineering-grade results.