GLM-4.5 and GLM-4.5-Air

What it is

GLM-4.5 is a large language model from Zhipu (Z.ai, 智谱), released in July 2025 together with GLM-4.5-Air, a smaller model in the same family. The weights were posted to Hugging Face on 20 July 2025.^[2][3]

Origins

The release came after a run of earlier models. In April 2025 Zhipu had released the GLM-4-0414 and GLM-Z1 reasoning models under the MIT License.^[2][3]

Main features

GLM-4.5 has 355 billion total parameters, of which 32 billion are active. GLM-4.5-Air has 106 billion total parameters and 12 billion active.^[1] Total parameters are all the weights in a model; active parameters are the ones used to process a given input. A gap between the two numbers reflects a sparse design such as the mixture-of-experts (MoE) architecture, in which only part of the network runs for each token.

Both models are hybrid reasoning models. Each has a thinking mode for complex reasoning and tool use, and a non-thinking mode for instant answers.^[1] Tool use means the model can call external functions, such as search or code execution, while it works on a task.

The models support up to 128K tokens of context and OpenAI-style tool calling. They are served through the Z.ai API Platform and the Zhipu AI Open Platform.^[1] A context window is the amount of text a model can take into account at one time.

Across 12 industry benchmarks, GLM-4.5 scored 63.2, ranking third among all proprietary and open models. GLM-4.5-Air scored 59.8.^[1] A benchmark is a standard test set used to compare models on the same tasks.

Wikipedia notes that GLM-4.5 can run on eight NVIDIA H20 chips.^[2] The technical report, arXiv 2508.06471, was published on 8 August 2025.^[1]

Licence

Both models are released under the MIT License, which permits commercial use. Wikipedia says the GLM family has been MIT-licensed since July 2025.^[1][2] MIT is a short, permissive open-source licence, so users can use, modify and redistribute the models with few restrictions.

Its place in development

GLM-4.5V followed in August 2025, and GLM-4.6 in September 2025.^[2] GLM-4.5 is therefore the model that sits between the April 2025 GLM-4-0414 and GLM-Z1 releases and the later versions of the series.