GLM-5.2 is probably the most powerful text-only open weights LLM

# GLM-5.2 is probably the most powerful text-only open weights LLM Source: [https://simonwillison.net/2026/Jun/17/glm-52/](https://simonwillison.net/2026/Jun/17/glm-52/) 17th June 2026 Chinese AI lab[Z\.ai](https://z.ai/)released GLM\-5\.2[to their coding plan subscribers](https://x.com/Zai_org/status/2065704919299235870)on June 13th, and then yesterday \(June 16th\) released the full open weights under an MIT license\. Similar in size to their previous GLM\-5 and GLM\-5\.1 releases, this is 753B parameter,[1\.51TB](https://huggingface.co/zai-org/GLM-5.2)monster—with 40 active parameters \(Mixture of Experts\)\. GLM\-5\.2 is a text input only model—Z\.ai have a separate vision family most recently represented by[GLM\-5V\-Turbo](https://x.com/Zai_org/status/2039371126984360085), but that one isn’t open weights\. GLM\-5\.2 has a 1 million token context window, up from GLM\-5\.1’s 200,000\. The buzz around this model is strong\. Artificial Analysis, who run one of the most widely respected independent benchmarks:[GLM\-5\.2 is the new leading open weights model on the Artificial Analysis Intelligence Index](https://artificialanalysis.ai/articles/glm-5-2-is-the-new-leading-open-weights-model-on-the-artificial-analysis-intelligence-index)\. > **GLM\-5\.2 is the leading open weights model on the Intelligence Index v4\.1\.**At 51, it leads MiniMax\-M3 \(44\), DeepSeek V4 Pro \(max, 44\) and Kimi K2\.6 \(43\) They did however find it to be quite token\-hungry: > **GLM\-5\.2 uses more output tokens per task than other leading open weights models:**the model uses 43k output tokens per Intelligence Index task, up from GLM\-5\.1 \(26k\) and above MiniMax\-M3 \(24k\), Kimi K2\.6 \(35k\) and DeepSeek V4 Pro \(max, 37k\) The model is also now ranked 2nd on the[Code Arena WebDev leaderboard](https://arena.ai/leaderboard/code/webdev), behind only Claude Fable 5\. That leaderboard measures “front\-end web development tasks, including agentic coding workflows”\. I’m impressed to see it rank so highly given the lack of image input, which I had incorrectly assumed was a key part of building a truly great frontend coding model\. I’ve been trying it out[via OpenRouter](https://openrouter.ai/z-ai/glm-5.2), which has it from 9 different providers, almost all of which are charging $1\.40/million for input and $4\.40/million for output\. For comparison, GPT\-5\.5 is $5/$30 and Claude Opus 4\.5\-4\.8 is $5/$25\. #### Excellent pelican, disappointing opossum GLM\-5\.1 gave me[one of my favorite pelicans](https://simonwillison.net/2026/Apr/7/glm-51/)and my[all time favorite opossum](https://simonwillison.net/2026/Apr/7/glm-51/#opossum)\(for the prompt “Generate an SVG of a NORTH VIRGINIA OPOSSUM ON AN E\-SCOOTER”\.\) Interestingly, in both of those cases the model chose to return SVG wrapped in an HTML document that added additional animations using CSS\. Let’s try GLM\-5\.2\. For “Generate an SVG of a pelican riding a bicycle” I[got this](https://gist.github.com/simonw/5c989366b796f054d9ae1ad7e38dc03a):  It’s a self\-contained fully animated SVG, and the animations aren’t broken\! Often I’ll see eyes falling off or wheels rotating independently of the bicycle but here everything works great\. It’s a very nice vector illustration of a pelican too\. Very impressive\. Sadly, the NORTH VIRGINIA OPOSSUM ON AN E\-SCOOTER did not come out[nearly as well](https://gist.github.com/simonw/5913b56e3d0ba9a2ece75ce1471f87bb):  This is such a step down from GLM\-5\.1\! As a reminder, that possum looked like this:  5\.2 didn’t even*try*to animate it\.