GLM-5.3 hits the API at $1.4/$4.4 per million tokens

After a stunning debut last week with cyber capabilities so advanced they reportedly found a previously undetected vulnerability in Cursor, GLM-5.3, the new frontier open source language model from Chinese startup z.ai, has now hit the application programming interface (API) — allowing developers the ability to build atop it and plug it into their agents and applications. Developers who previously subscribed to a GLM Coding Plan are currently limited to the OpenAI Chat Completions-compatible protocol. Z.ai said it plans to make the model's weights openly available, but a precise date and licensing remain to be seen. On the API, the price is unchanged from GLM-5.2: $1.40 per million input tokens and $4.40 per million output tokens. Cached input costs $0.26 per million tokens, while Z.ai currently lists cached-input storage as free for a limited time. That means developers can move to the new generation without taking a higher posted per-token rate from Z.ai, even as the company claims substantially stronger coding and long-horizon agent performance. At those rates, GLM-5.3 sits well below several of the highest-end frontier APIs. ModelInput ($/1M)Output ($/1M)Total ($/1M)Sourc…