Kapitsa: open-source Apple Silicon inference engine tuned for Qwen and Nemotron
Developer Ye at Nace.ai posted Kapitsa on r/LocalLLaMA, an Apache 2.0 open-source inference engine for Apple Silicon aimed at running coding agents on local models on Macs. Kapitsa supports only two model families — Qwen (3.5 4B, 3.8 27B, 3.6 35B-A3B and 3.8 Flash-Next) and NVIDIA Nemotron (3.5 Lightning, Bolt, Super-VL plus Dory 4B) — so the team can customize Metal kernels per architecture. The author published decode-speed tables on M1 Pro 16GB, M4 Pro 48GB and M5 Max 128GB machines, claiming it beats mlx-serve, oMLX, Ollama, MLX and llama.cpp in most cases, while trailing mlx-serve and oMLX by roughly 2-3% on Qwen3.8 Flash-Next. He also warns readers not to trust benchmarks, points them to a built-in kapitsa bench command to test themselves, notes that 4-bit quantization costs some quality, and says the new codebase should be expected to have bugs.
The author says the motivation is enterprise networks with no internet access and outdated cloud models, so coding agents must run on local Macs; all performance figures are self-reported and the author himself cautions against trusting them.
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