Moonshot AI has released Kimi K3, a 2.8-trillion-parameter mixture-of-experts model with 104 billion activated parameters, native vision, and a 1-million-token context window, and it has published the full weights. The technical report is the first open release to reach the three-trillion-parameter class, and the headline architectural claims are concrete: the model is built on Kimi Delta Attention and Attention Residuals, which the team credits with improving information flow both across sequence length and across model depth, and on Stable LatentMoE, which activates 16 of 896 routed experts per token. Combined with revised training and data recipes, Moonshot reports roughly a 2.5x improvement in overall scaling efficiency relative to Kimi K2.
Post-training is where the report spends most of its capability argument. Reinforcement learning is applied across general, agentic, and coding domains, and across multiple reasoning-effort levels, which the authors tie to compositional generalization and to robust long-horizon execution rather than to single-turn benchmark gains. The infrastructure section is unusually specific for an open release: algorithm-system co-design for Kimi Delta Attention, perfectly balanced expert-parallel training with explicit memory management, and million-token agentic RL with persistent rollout and sandbox state, which is the part that matters if you want to reproduce long-horizon agent training at this scale rather than just run inference.
The self-assessment is candid. Moonshot states that K3's overall performance still trails the most powerful proprietary models, naming Claude Fable 5 and GPT-5.6 Sol, while claiming it consistently outperforms every other open and proprietary model in their evaluation suite across long-horizon coding, agentic, knowledge, reasoning, and vision tasks. That framing — deliberately close to the frontier, explicitly not at it — is a shift from the usual open-release posture of claiming parity.
Availability moved fast. Telnyx put the model live on its inference API the same day under the identifier moonshotai slash Kimi-K3, running on its own GPU infrastructure behind an OpenAI-compatible endpoint, at two dollars seventy per million input tokens and thirteen dollars fifty per million output tokens, with cached input at twenty-seven cents, exactly one tenth of uncached. Three configurable reasoning-effort levels, function calling, dynamic tool loading, and JSON-schema-constrained output are exposed. Notably, Telnyx's release notes carry no benchmark numbers at all, so the only quantitative claims in circulation on day one are Moonshot's own.
The release lands in the middle of an active policy argument about whether US companies should be permitted to use Chinese open-weights models, which makes the timing of a frontier-adjacent Chinese open release its own kind of data point.
- The arXiv report frames the contribution as scaling efficiency, crediting Kimi Delta Attention plus Stable LatentMoE for a 2.5x gain over K2.
- Telnyx pitched availability and price on day one but published no benchmark numbers behind its 'competes with closed frontier models' claim.
- Hacker News discussion centered on the 2.8T total parameter count and what self-hosting a 104B-active model actually costs.
- Moonshot itself concedes K3 trails Claude Fable 5 and GPT-5.6 Sol, which is a more restrained claim than most open releases make.