The Python Language Server for Professionals

A Mypy-compatible Python Language Server built in Rust

Standards⁠-⁠compliant

Fully Featured Type System

Unparalleled Performance

Free For Most Download

Performance

Extremely fast. Generally 20-200x faster than Mypy - and optimized for lower memory usage.

Features

Only diagnostics are supported. Features such as completions and go-to-definition are currently in development.

Creation

Developed by the creator of Jedi, ZubanLS applies 14 years of experience in Python auto-completion and static analysis.

Alpha

As an Alpha release, some false positives are expected. Issues will be addressed promptly. A beta release will soon be available.

Works in VSCode,

ZubanLS

Vim,

ZubanLS

and all other LSP-compatible editors

This includes Helix, NeoVIM, SublimeText, Emacs, Zed and many others

pip install zuban

ZubanLS

All Features

Development Tooling

  • Mypy config compatibility
  • Error recovery
  • Incremental checking
  • Watches files
  • Python 3.13 support

General Code Understanding

  • Passes >95% of Mypy's relevant tests
  • Relative, absolute, and stub-only (`.pyi`) imports
  • Type narrowing isinstance, assert, etc
  • Inferring the type context
  • Mypy's --new-type-inference
  • Understanding list.append, etc

Performance

  • Written in Rust
  • More than 20-200x faster than Mypy
  • Optimized to minimize memory usage

Type System Support

  • TypeVar / TypeVarTuple / ParamSpec
  • Overloads / NewType / Overrides
  • Dataclasses / dataclass_transform
  • TypedDict / NamedTuple / Enum
  • NewType
  • Protocols / Union Types
  • Literal Types
  • Final / ClassVar / Annotated
  • Self Types
  • Generic Defaults
  • TypeGuard / TypeIs
  • ... and much more

Executables

  • zubanls - A language server
  • zmypy - A drop in replacement for Mypy
  • Works on Linux, Mac and Windows
A more comprehensive list can be found in the Documentation. General plugin support is not planned; however, targeted plugins for popular libraries, such as Django, will be provided.

Pricing

During the alpha period, all ZubanLS releases are available at a 100% discount. Happy coding!

Pricing is based on code size—a simple metric. Most users receive the language server for free; only large codebases require a paid license.

Learn more

The ZubanLS Company

In 2012, I created Jedi—a Python auto-completion library that eventually reached millions of users and billions of downloads. But as the ecosystem evolved, one limitation became clear: speed. Jedi’s architecture couldn’t deliver the performance needed for large-scale projects.

In 2020, I started over—with everything I’d learned—building ZubanLS from the ground up in Rust. After five years of full-time work, ZubanLS is now the first truly fast Python language server.

ZubanLS is built for professionals who need precision, reliability and speed. It addresses long-standing issues in tools like Mypy and Pyright by focusing on performance without compromising features. Support for Django, go-to-definition, completions, and other LSP features is underway. The goal: a tool for perfectionists with deadlines.

The initial 2025 release may not meet every need. If something essential is missing for your use case, feel free to —we’re open to implementing features based on real-world demand.

ZubanLS

David Halter

Founder