SWE – 1 – The first series of AI models for software engineering launched by Windsurf

What is SWE-1?

SWE-1 is the first AI model series launched by the Windsurf team, designed specifically to optimize the entire software engineering workflow. It enhances key development processes including code generation, testing, debugging, and documentation lookup, aiming to improve both developer productivity and user experience.

The SWE-1 series includes three models:

• SWE-1: A high-performance model comparable to Claude 3.5 Sonnet in reasoning ability but with lower service costs. During the promotional period, it’s available to all paid users for free.

• SWE-1-lite: A compact and high-quality alternative to Cascade Base, available for unlimited use by all users, including free-tier users.

• SWE-1-mini: A lightweight, fast-response model optimized for speed, available to all users (including free users) and integrated with Windsurf Tab.

By developing its own models, Windsurf can better serve developer needs, building unique technical barriers and a distinct product experience.

SWE-1 Model Family

• SWE-1: Offers capabilities close to Claude 3.5 Sonnet with lower costs. Free for all paid users during the launch period.

• SWE-1-lite: A lightweight, high-quality model that replaces Cascade Base. Available with unlimited use for all users.

• SWE-1-mini: An ultra-fast, compact model integrated into the Windsurf Tab, accessible to all users.

Key Features of SWE-1

• Flow Awareness: Understands multiple states and contexts within software development, enabling continuous progress through complex workflows such as human-AI collaboration, task interruption, and resumption.

• Code Generation & Optimization: Generates high-quality code and provides optimization suggestions to accelerate development.

• Testing & Debugging Assistance: Assists in generating test cases and locating debugging issues, reducing the time required for QA processes.

• Documentation Generation & Understanding: Automatically creates documentation for code, helping developers quickly grasp functionality and structure.

• Task Planning & Management: Helps developers organize and manage tasks, track progress, and receive intelligent reminders.

Technical Foundations

• Shared Timeline: SWE-1 leverages a shared timeline mechanism to enable real-time interaction awareness. This allows the AI to intervene meaningfully at any stage of user activity.

• Flow Awareness: Integrates various elements of the Windsurf Editor—such as code edits, terminal output, clipboard content—into a shared timeline. This empowers the AI to adjust its behavior dynamically based on user actions.

• Training Approach: SWE-1 is trained using a new data model optimized for the complexity and long-term nature of software engineering. It can handle incomplete states and ambiguous results, closely simulating real-world development scenarios. Training emphasizes code correctness, task completeness, and long-term goal alignment. Continuous optimization is driven by real-world development data and user feedback.

Official Evaluation

• Evaluation Methodology: Windsurf conducted offline evaluations (e.g., dialog-based tasks, end-to-end workflows) and real-user blind tests, comparing SWE-1 to leading proprietary (Anthropic) and open-source (Deepseek, Qwen) coding models.

• Results: SWE-1 achieved performance that meets or approaches industry-leading standards in metrics like “lines of code adopted by users” and “model contribution rate.” Many users reported that the AI suggestions were highly accurate and significantly improved their development efficiency.

Project Information

• Official Website: https://windsurf.com/blog/windsurf-wave-9-swe-1

Application Scenarios

• Code Generation & Optimization: Quickly generate high-quality code with actionable optimization suggestions.

• Testing & Debugging Support: Automatically generate test cases and assist with debugging tasks.

• Automatic Documentation: Create detailed documentation based on source code to support understanding and maintenance.

• Task Planning & Tracking: Assist developers in planning and tracking project tasks, improving project management efficiency.

• Human-AI Collaborative Development: Enable smooth collaboration between human developers and AI in team settings.