Z.ai published a post titled “GLM-5.3-Flash.” The available source text provides no details about the model’s capabilities, release date, technical specifications, pricing, benchmarks, availability, or intended use. The post was submitted by Philpax and had received 529 points and 239 comments at the time represented by the source text.

Z AI released the proprietary reasoning model GLM-5.3 (max) on August 18, 2026. The model accepts and generates text only, does not process images, and supports a 1 million-token context window, roughly equivalent to 1,500 A4 pages in 12-point Arial. It has 753 billion parameters and is available through one API provider. GLM-5.3 (max) scored 60 on the Artificial Analysis Intelligence Index, compared with a median score of 35 for reasoning models in a similar price tier. The composite index measures capabilities including reasoning, knowledge, mathematics and coding. The model produced 170 million output tokens during the evaluation, substantially above the 72 million-token median for comparable models, and the full evaluation cost $1,238.50. Z AI’s API pricing is $1.40 per million input tokens and $4.40 per million output tokens, versus medians of $1.75 and $10.00, respectively, for comparable models. Artificial Analysis calculates a blended price of $0.90 per million tokens using a 7:2:1 cache-hit, input and output token mix. The model uses extended thinking or chain-of-thought reasoning for complex problems, while its weights are not publicly available.

GLM-5.1 introduces enhancements for long-horizon tasks, improving the model's ability to manage extended interactions and complex reasoning. The update focuses on refining task planning and execution capabilities for AI applications.