GLM-5.1 vs Meta Muse Spark

GLM-5.1 is Z.ai's (formerly Zhipu AI) open-weight model released April 7, 2026 under the MIT license. It's a 744-billion-parameter Mixture-of-Experts architecture with 40 billion active parameters per token, a 200K-token context window, and a 131K maximum output length — and it became the first open-source model ever to lead SWE-bench Pro, scoring 58.4% versus Claude Opus 4.6's 57.3%. The training story is almost as remarkable as the performance. GLM-5.1 was trained entirely on approximately 100,000 Huawei Ascend 910B chips using the MindSpore framework — no Nvidia hardware was used at any point. That makes it one of the first frontier-tier models to demonstrate that the CUDA monoculture isn't technically mandatory for training state-of-the-art models. Z.ai became the first publicly traded foundation model company via a Hong Kong IPO in January 2026 (~$558M raised). The model is free to download from HuggingFace and also available via API at $0.95 per million input tokens. In agentic demonstrations, it has run autonomously for eight hours straight — 655 planning and execution iterations — without human checkpoints.

Meta unveiled Muse Spark on April 8, 2026 — the first model from Meta Superintelligence Labs (MSL), led by former Scale AI CEO Alexandr Wang. It marks a dramatic break from Meta's Llama-era open-source identity: Muse Spark is fully proprietary, with only a vague promise that "future versions may be open-sourced." The model currently powers the Meta AI app, meta.ai website, and is rolling out to WhatsApp, Instagram, Facebook, Messenger, and Ray-Ban Meta AI glasses. Muse Spark is natively multimodal — it handles text and images, launches parallel subagents for complex requests, and emphasizes real-world utility: analyzing product photos for nutritional comparisons, generating full websites from descriptions, and supporting health-related image analysis with physician oversight. A private API preview is available to select partners. No benchmark data was disclosed at launch, which raised eyebrows in the community. For users, Muse Spark is accessible for free through Meta's consumer apps. For developers, the closed API is a sharp contrast to the Llama ecosystem that helped Meta build enormous developer goodwill. The model is reportedly built on significantly more efficient architecture — "an order of magnitude less compute than older midsize Llama 4 variants" — which suggests MSL's infrastructure rebuild is paying off. Whether the quality matches the ambition awaits independent evaluation.