GLM is the flagship model family from Zhipu AI, the Chinese lab internationally branded as Z.ai. Zhipu was spun out of Tsinghua University in 2019 and has grown into one of the most closely watched AI companies in the world. In January 2026 it listed on the Hong Kong Stock Exchange (among the first standalone AI-model developers to go public), with backing from Alibaba, Tencent, Meituan, Xiaomi and others. GLM stands for "General Language Model," and its current flagship is GLM 5.3, released in August 2026.
What makes GLM 5.3 stand out is its positioning as one of the top open-weight models for coding and agentic work. Z.ai publishes its weights: GLM 5.3 went up on Hugging Face on August 28, 2026, under Z.ai's own license, and the lighter GLM 5.3 Flash arrived two days earlier under plain MIT. Anyone can download, inspect, modify, and self-host either one. It lists at $1.40 per million input tokens and $4.40 output, about a third of Claude Opus 5.5's input price and a fifth of its output, and it supports a context window of up to 1M tokens. That combination has made it a favorite for developers who want a capable model they can actually run and audit themselves.
For everyday work, GLM 5.3 shines inside agent harnesses and coding tools like Claude Code, Cline, and Roo Code, where it can run long, multi-step autonomous tasks without losing the thread. It also handles general reasoning, writing, and Q&A competently. It trails the very top closed models on the hardest reasoning problems, but as a cost-efficient, tool-using workhorse it is genuinely compelling.
GLM vs GLM 5.3: GLM ("General Language Model") is the model family from Zhipu AI, branded internationally as Z.ai. 5.3 is the current flagship version, tuned for coding and agentic tasks. In Fello AI, GLM queries are routed through secure US-based servers, not through Z.ai's own infrastructure.