# Used GLM 5.3 Flash for Code

> Source: <https://www.dotnetperls.com/2026_9_24_used-glm-53-flash-code>
> Published: 2026-09-24 07:00:00+00:00

Yesterday I wrote 2 more **specs** for my program, and needed a LLM to **generate** the **code**. I used OpenRouter and decided to try out **GLM 5.3 Flash**. My total bill for the endeavor came out to about 3 cents ($0.03).

After using GLM 5.3 Flash I can see why some people want to buy expensive computers and run it locally all day—it is a **nice model**. It coded the functions well, and worked quickly. Both of the Rust functions were **optimized** in ways better than the original versions.

Some notes on spec-driven development:

• There is a "complexity level" that is ideal.

• Writing a complete spec for a simple function is kind of a waste of time; and code that is too complex also needs more than a single specification.

• Using a handful of specs and generating code for them via chat on OpenRouter is surprisingly cost-efficient, even with models like GPT-6-Sol.