1
Pyright
Shares tags: ai
AI Tool
Pyre Review
Pyre is a fast, integrated type-checker for Python 3, enhancing code quality and security with static analysis.
1Pyre is a static type checker for Python 3, developed by Meta (formerly Facebook and Instagram).
2It supports gradual typing and delivers responsive incremental checks on large codebases.
3Pyre integrates Pysa, a security-focused static analysis tool, to identify potential security issues and reason about data flows.
4The tool is open-source and available for free, with no associated pricing plans.
⚡
Pyre at a Glance
Connect
</>Embed "Featured on Stork" Badge▼
<a href="https://www.stork.ai/en/pyre" target="_blank" rel="noopener noreferrer"><img src="https://www.stork.ai/api/badge/pyre?style=dark" alt="Pyre - Featured on Stork.ai" height="36" /></a>
[](https://www.stork.ai/en/pyre)
overview
What is Pyre?
Pyre is a static type checker tool developed by Meta (formerly Facebook and Instagram) that enables developers to enhance code quality and security with static analysis. It supports gradual typing and delivers responsive incremental checks on large codebases. Designed for Python 3, Pyre performs static analysis to identify type-related bugs before runtime, improving code readability and maintainability. A key differentiator is its integration with Pysa, a security-focused static analysis tool that reasons about data flows in Python applications at scale to detect potential vulnerabilities. Pyre is built for performance on extensive codebases, including those with millions of lines of Python code, providing quick feedback through incremental checks. Meta is currently transitioning development efforts to Pyrefly, a Rust-based successor aiming for enhanced type inference and performance, with an early preview playground made available in March 2025.
quick facts
Quick Facts
| Attribute | Value |
|---|---|
| Developer | Meta (formerly Facebook and Instagram) |
| Business Model | Open Source |
| Pricing | Free |
| Platforms | Python 3 |
| API Available | No |
| Integrations | Language Server Protocol (LSP), VSCode extension |
| Privacy Policy URL | https://opensource.meta.com/legal/privacy/ |
| Training on User Data | Never |
features
Key Features of Pyre
Pyre offers a robust set of features designed to improve Python code quality, security, and developer efficiency through static analysis:
- 1Performant static type checking for Python 3 codebases.
- 2Support for gradual typing, allowing incremental annotation of existing untyped code.
- 3Responsive incremental checks, optimized for large codebases with millions of lines of code.
- 4Interactive flagging of type errors directly in the terminal or within integrated development environments (IDEs) via editor extensions.
- 5Integration with Pysa, a security-focused static analysis tool, for deep data flow analysis.
- 6Identification of potential security issues and reasoning about data flows within Python applications.
- 7Enhances overall code quality and accelerates development speed by catching errors early.
- 8Supports the Language Server Protocol (LSP) for broad IDE compatibility.
- 9Provides a dedicated VSCode extension for an integrated user experience.
use cases
Who Should Use Pyre?
Pyre is primarily targeted at developers and organizations seeking to enhance the reliability, maintainability, and security of their Python 3 applications. Its design caters to specific development needs:
- 1Developers: For early bug detection, improving code quality, and ensuring type consistency in Python projects during the development phase.
- 2Organizations with large Python codebases: To leverage performant incremental type checking, maintain code health, and manage complexity across extensive projects.
- 3Teams focused on application security: To utilize Pysa's capabilities for identifying data flow vulnerabilities and potential security issues within their Python applications.
- 4Developers migrating untyped codebases: To gradually introduce type annotations and transition to fully typed code without disrupting existing functionality.
pricing
Pyre Pricing & Plans
Pyre is an open-source tool and is available for free. There are no direct pricing plans, subscription costs, or paid tiers associated with its use. It can be installed via pip, the Python package installer, without any licensing fees. Meta, its developer, maintains Pyre as a community-driven project, making its advanced static analysis and security features accessible to all Python developers.
- 1No paid tiers available.
competitors
Pyre vs Competitors
Pyre operates within a competitive landscape of Python static type checkers, each with distinct strengths and development philosophies:
1
MyPy↗
MyPy is the original and most widely adopted static type checker for Python, often considered the reference implementation for Python's type system.
MyPy is a mature and comprehensive type checker, similar to Pyre in its support for gradual typing, but it is written in Python and can be slower on large codebases compared to Pyre's OCaml implementation.
2
Pyright↗
Developed by Microsoft, Pyright is known for its high performance, strong conformance to Python typing specifications, and deep integration with Visual Studio Code via the Pylance extension.
Pyright is generally faster than MyPy and offers excellent IDE integration, making it a strong alternative to Pyre for large projects, though it is written in TypeScript and runs on Node.js.
3
Pyrefly↗
As the successor to Pyre, Pyrefly is a Rust-based type checker from Meta designed for extreme performance and open-source engagement, aiming to be significantly faster than previous generation type checkers.
Pyrefly is positioned as a direct evolution and replacement for Pyre, offering superior speed and portability due to its Rust implementation, and is actively being developed to replace Pyre by the end of 2025.
❓
Frequently Asked Questions
+What is Pyre?
Pyre is a static type checker tool developed by Meta (formerly Facebook and Instagram) that enables developers to enhance code quality and security with static analysis. It supports gradual typing and delivers responsive incremental checks on large codebases.
+Is Pyre free?
Yes, Pyre is an open-source tool and is entirely free to use. There are no pricing plans, subscription costs, or paid tiers associated with its installation or operation.
+What are the main features of Pyre?
Pyre's main features include performant static type checking for Python 3, support for gradual typing, responsive incremental checks on large codebases, interactive error flagging, and integration with Pysa for security-focused static analysis to identify data flow vulnerabilities. It also supports the Language Server Protocol (LSP) and has a VSCode extension.
+Who should use Pyre?
Pyre is ideal for developers and organizations working with Python 3 who need to improve code quality, ensure type consistency, and enhance security through static analysis. It is particularly beneficial for managing large codebases, gradually adding type annotations, and identifying security vulnerabilities with Pysa.
+How does Pyre compare to alternatives?
Pyre differentiates itself from alternatives like MyPy and Pyright through its performance on large codebases, its OCaml implementation, and its unique integration with Pysa for security analysis. While MyPy is widely adopted and Pyright offers exceptional speed and IDE integration, Pyre's successor, Pyrefly (developed in Rust), aims to surpass both in performance and capabilities.