In the latest release of PyCharm (2026.1.2), developers can now activate Pyrefly as an external type provider, delivering a dramatic boost to the speed of the IDE's code intelligence features. By replacing the built-in type engine with Meta's next-generation Python type checker, PyCharm users can enjoy faster performance without sacrificing accuracy. This article explores what Pyrefly LSP is, its benefits, and how to enable it in your projects.
Understanding the Language Server Protocol (LSP)
The Language Server Protocol (LSP) is a standardized communication protocol that enables code editors and integrated development environments (IDEs) to interface with language servers. Instead of each tool implementing its own language-specific intelligence, LSP allows a single server to provide common features across many editors, IDEs, and even CI pipelines. Key capabilities include:
- Code completion – Intelligent suggestions as you type
- Hover information – Quick documentation and type details
- Go to Definition – Navigate to symbol declarations
- Error checking and diagnostics – Real-time type and syntax errors
This unified approach means language servers like Pyrefly can be reused in multiple tools, reducing duplication and ensuring consistent behavior.
Introducing Pyrefly: Meta's Next-Generation Python Type Checker
From Pyre to Pyrefly: A Rust-Based Evolution
Meta has been developing advanced Python type checkers for years, starting with Pyre, written in OCaml. Their latest project, Pyrefly, is a complete rewrite in Rust – a language known for its speed and cross-platform portability. This transition isn't just cosmetic; it delivers tangible improvements in performance, making Pyrefly significantly faster than its predecessor. Moreover, Rust's safety guarantees and modern toolchain make Pyrefly more robust and easier to maintain across different operating systems.
Key Benefits of Pyrefly
Using Pyrefly as your type engine brings several advantages, especially for large, complex Python codebases:
- Higher performance and efficiency – The Rust architecture maximizes speed while reducing resource overhead. This translates to quicker code insight and a snappier IDE experience.
- Enhanced code intelligence – Pyrefly powers type inference, type-related diagnostics, quick documentation, and inlay hints with greater accuracy and speed than the default engine.
- Scalability – Designed to handle massive codebases with high precision, Pyrefly copes well with projects containing thousands of modules and dependencies.
These features make Pyrefly an excellent choice for teams working on large-scale Python applications that cannot afford slowdowns in their development tools.
Enabling Pyrefly in PyCharm 2026.1.2
Activating Pyrefly in PyCharm is straightforward. The IDE includes a dedicated Type widget located at the bottom of the main window. By default, PyCharm uses its internal type engine. To switch to Pyrefly:
- Click on the Type widget in the status bar (usually displays "Type Engine").
- Select the option to use Pyrefly from the dropdown menu.
- If Pyrefly is not already installed on your system, PyCharm will automatically download and install it.
Once enabled, you'll see a Pyrefly icon appear at the bottom. Hover over it to see the version currently in use, ensuring you're running the latest compatible release.
Current Limitations and Future Plans
At present, the integration works only with local interpreter configurations. PyCharm’s team has announced that support for Docker, Docker Compose, WSL, SSH, and multi-module projects is planned for upcoming releases. Until then, users working exclusively with local interpreters can still take full advantage of Pyrefly’s speed and accuracy.
Conclusion
The integration of Pyrefly via LSP marks a significant step forward for Python development in PyCharm. By leveraging Meta's Rust-based type checker, developers can dramatically improve code insight performance without changing their workflow. Whether you maintain a large enterprise codebase or simply want a faster, more responsive IDE, enabling Pyrefly in PyCharm 2026.1.2 is a quick win. Try it today and experience the difference firsthand.