GLM-5 or Muse Spark Open: which to choose?

What are we comparing?

This comparison pits two open-weight models that you can install on your own servers against each other: GLM-5 and Muse Spark Open, one from Zhipu AI (Z.ai), the other from Meta. The first dates from February 12, 2026, the second from October 15, 2026.

All figures below come from public sources checked on October 22, 2026: models.dev and OpenRouter for prices and capabilities, Epoch AI for scores.

What the benchmarks say

On our capability index, GLM-5 scores 77.2 out of 100 and Muse Spark Open 75.2. GLM-5 leads by 2 points.

On the 2 benchmarks reported for both, GLM-5 wins 0 times and Muse Spark Open 2:

• GPQA Diamond (PhD-level science questions): GLM-5 87.8%, Muse Spark Open 88.6%
• OTIS Mock AIME (competition mathematics problems): GLM-5 80%, Muse Spark Open 98.1%

Pricing

GLM-5 costs $0.60 per million input tokens and $2.69 per million output tokens; Muse Spark Open costs $1.25 and $4.25.

For a typical agent task (read 20,000 tokens, write 2,000), expect $0.017 with GLM-5 versus $0.034 with Muse Spark Open. GLM-5 is 1.9 times cheaper, a gap that adds up quickly over 1,000 tasks: $16.17 difference.

Run the numbers with your own volumes in the agent cost calculator.

Under the hood

Muse Spark Open reads more in one go: 1,048,576 tokens of context (roughly 1,573 pages), versus 204,800 for GLM-5.

Reasoning mode: GLM-5 yes, Muse Spark Open yes. Tool calling: GLM-5 yes, Muse Spark Open yes. Image input: GLM-5 no, Muse Spark Open yes.

Both publish their weights: you can host them yourself.

In short

Our reading of the data:

• Choose GLM-5 for a higher capability index and a lower cost.
• Choose Muse Spark Open for a larger context window, a more recent release and image input.

This verdict relies on public figures; it does not replace a trial on your own tasks.