Devstral 2 Review 2026: Mistral's Open-Source Coding Agent Hits 72.2% SWE-bench
Devstral 2 is Mistral AI’s most capable open-weight coding model, achieving 72.2% on SWE-bench Verified — the highest score ever recorded by an open-source model at its parameter count. Released in late 2025 alongside the Mistral Vibe CLI, it costs $0.40 per million input tokens, making it up to 7x cheaper than Claude Sonnet for typical coding workloads. What Is Devstral 2? Overview of Mistral’s Latest Open-Source Coding Agent Devstral 2 is a 123-billion parameter open-weight large language model purpose-built for agentic software engineering tasks — it can autonomously navigate codebases, edit multiple files, run tools, and resolve GitHub issues end-to-end. Released by Mistral AI in December 2025, it achieves 72.2% on SWE-bench Verified (the industry-standard benchmark for autonomous bug-fixing), placing it at the frontier of all open-weight models and ahead of significantly larger competitors including DeepSeek V3.2 (672B) and Kimi K2 (1T). Unlike most frontier coding models, Devstral 2 is released under the Apache 2.0 license, meaning developers can download, self-host, fine-tune, and deploy it commercially without restriction. In human evaluations against DeepSeek V3.2, Devstral 2 wins 42.8% of coding tasks versus a 28.6% loss rate — a meaningful real-world advantage that SWE-bench alone doesn’t fully capture. The model supports a 256K-token context window, enabling comprehension of entire repositories in a single pass. For teams that need frontier-grade coding intelligence without proprietary lock-in, Devstral 2 is the clearest option available in 2026. ...