Mistral AI Unveils Devstral 2: The 123B Coding Giant

Introduction

Mistral AI has officially announced the release of Devstral 2 on December 9, 2025, marking a significant milestone in the evolution of open-source coding assistants. This model represents a paradigm shift in how developers interact with AI, offering a massive 123 billion parameter architecture that rivals proprietary giants while maintaining full community accessibility. The release addresses the critical need for high-performance coding models that do not compromise on data privacy or licensing terms, setting a new standard for the industry.

• Released on 2025-12-09
• 123 Billion Parameters
• Open Source License
• Top SWE-Bench Score

Key Features & Architecture

Devstral 2 utilizes a sophisticated Mixture of Experts (MoE) architecture designed to optimize inference speed without sacrificing reasoning capabilities. The model supports a massive 128,000 token context window, allowing it to ingest entire codebases and documentation in a single prompt. Unlike previous iterations, Devstral 2 includes enhanced multimodal capabilities, enabling it to interpret code screenshots and diagrams directly. This architecture ensures that the model can handle complex, multi-file refactoring tasks with precision.

• MoE Architecture for Efficiency
• 128k Context Window
• Multimodal Code Interpretation
• Modified MIT License

Performance & Benchmarks

In terms of raw capability, Devstral 2 sets new records on industry-standard benchmarks. It achieves a top-tier score of 85.4% on the SWE-Bench Hard track, significantly outperforming its predecessor and competing directly with closed-source enterprise models. On HumanEval, the model scored 92.1%, demonstrating superior ability to generate syntactically correct and functional code snippets. Furthermore, the MMLU score reached 88%, indicating robust general reasoning skills that extend beyond simple syntax completion.

• SWE-Bench: 85.4%
• HumanEval: 92.1%
• MMLU: 88%
• Top-tier Reasoning

API Pricing & Licensing

Mistral AI has introduced a unique pricing model for Devstral 2 that balances accessibility with sustainability. The API costs are set at $0.50 per million tokens for input and $1.50 per million tokens for output. A generous free tier is available for developers and small projects, ensuring that cost does not become a barrier to entry. Additionally, the model is released under a Modified MIT license, meaning it is free for commercial use unless the project generates high revenue, protecting smaller startups while allowing enterprise scaling.