GLM-5.1: The 754B Open Model That Writes Animated SVG

GLM-5.1 just landed from Z.ai - a 754B parameter, 1.51TB, MIT-licensed model available on Hugging Face and via OpenRouter.

Same size as their GLM-5 release, but with a twist: it generates animated SVG with CSS.

Simon Willison ran his pelican test. Most models produce static graphics. GLM-5.1 generated a full HTML page with CSS animations - the pelican's beak wobbles, wheels spin.

When the animation broke positioning, the model diagnosed the problem:

"The issue is that CSS transform animations on SVG elements override the SVG transform attribute used for positioning, causing the pelican to lose its placement. The fix is to separate positioning from animation and use for SVG rotations."

And then it fixed it.

This matters because most open-weight releases chase benchmarks. GLM-5.1 shows competence in a different domain: understanding that graphics exist in a rendering context, not just as static output.

The pelican test proxies whether a model understands that code runs somewhere - SVG has coordinate systems, CSS has cascade rules, "fix it" means understanding both.

What to watch: MIT-licensed at 754B parameters is unusually permissive for a model this size. If inference costs drop, GLM-5.1 becomes the "good enough" baseline for anyone not renting from OpenAI or Anthropic.

The test is not whether it draws pelicans. It's whether organizations ship it in production because the license lets them.