100% Only listed checker with a perfect official score 141 of 141 files pass the suite’s unmodified harness, with 0 missed required errors and 0 false positives. Official results, Jul 31, 2026.
10 ms Fastest in our published cold-check benchmark Basilisk’s median across 26 synthetic, single-file fixtures on Apple M4 Max. Fresh-process CLI timing; not project throughput or editor latency.
Conformance uses the official Python typing harness; performance is self-measured and reproducible. Verify the conformance score → Read the benchmark methodology →
What is Basilisk?
A Python type checker and language server, powered by one Rust analysis engine.
- 01 Check Python in your editor and CI. Typing-spec rules run by default; optional Basilisk rules can require annotations and other team conventions.
- 02 Understand the code. Autocomplete, hover, signature help, definitions, references, and inlay hints use the same type information.
- 03 Change it with context. Embedded Ruff formatting and import organization, plus rename, extract, inline, move, and targeted code actions.
Type checking is the core. The editor workflow goes further.
The VS Code extension, also installable in Cursor and Windsurf, adds test discovery and execution,
debugpy debugging, CPU profiling, and debug-session memory analysis.
These runtime workflows use your project’s Python interpreter.
Zed and Neovim connect to the same Basilisk language-server core; advanced surfaces follow each editor’s integrations.