Open-Source Alternatives to 
Claude Opus 5.5
The best open-weight, self-hostable alternatives to Claude Opus 5.5 in 2026 — compared on price, context window and capabilities. Run them locally and cut API costs.
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The best open-weight alternatives to Claude Opus 5.5
Claude Opus 5.5 is a proprietary, API-only model. These open-weight models can be self-hosted, run offline and used at a fraction of the cost — here's how the top ones stack up.
Kimi K3.1 Pro Open
Within 2.5 pts of Claude Opus 5.5 on the Artificial Analysis intelligence index · 2.0× cheaper per million output tokens
Kimi K3.1 Pro is Moonshot AI's flagship open-weight multimodal reasoning model and a post-trained successor to Kimi K3, with a 1M-token context window. It is built for long-horizon coding, 3D...
Kimi K3.1 Pro vs Claude Opus 5.5 →See the full open-source leaderboard
Live ranking of open-weight models with pricing, context windows and capabilities.
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