---
id: skylos
version: "4.33.2"
license: Apache-2.0
license_treatment: permissive
maintenance: active
---

# skylos — Open-source, local-first static analysis and PR gates for Python, TypeScript/JavaScript, Go, Java, Kotlin, PHP, Rust, Dart, C#, and Shell. Finds dead code, security issues, secrets, quality regressions, and AI-code mistakes.

License: permissive · Maintenance: active · Downloads: 173.7K/mo

## What it is and what it does

Skylos is a multi-language static analysis tool designed to run locally before code merge, checking for dead code, security vulnerabilities, exposed secrets, dependency CVEs, deployment misconfigurations, quality regressions, and mistakes commonly introduced by AI code generators. It supports 12 languages and can operate as a standalone CLI, GitHub Action, or CI/CD gate. The tool includes specialized checks for AI-generated code hallucinations—phantom functions, invented APIs, impossible dependency versions—and LLM app risks like unsafe tool use.

The package ships with 19 runtime dependencies, primarily tree-sitter language parsers and terminal UI libraries (rich, textual, inquirer), enabling both broad language coverage and an interactive terminal interface. It can output findings in multiple formats (pretty, concise, JSON) and includes a keyboard-driven TUI for triaging results. For AI-generated code, Skylos can verify against repo-specific contracts defined in `.skylos/ai-contract.yml`, reducing hallucination false positives by anchoring checks to actual project symbols and APIs.

Use it for:

- Scan a pull request for dead code and unused imports before merge using `skylos . --diff origin/main`
- Verify AI-generated code snippets for hallucinated functions, invented APIs, and missing guards with `skylos verify . --file src/app.py --range 40:75`
- Set up a GitHub Actions PR gate with `skylos cicd init` to block commits with security flaws, secrets, or quality regressions
- Audit a multi-language monorepo for security issues and dependency CVEs with `skylos . -a`
- Create project-specific static analysis rules with `skylos rules init` and validate them with `skylos rules validate`
- Compare Skylos findings against an incumbent scanner with `skylos compare . --against incumbent.sarif` to measure coverage overlap

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Skylos is a local-first static analysis CLI that scans Python, TypeScript, JavaScript, Java, Go, Kotlin, PHP, Rust, Dart, C#, Shell, and deployment configs for dead code, security flaws, secrets, quality regressions, and AI-generated code mistakes.

Yes. Skylos is actively maintained (5 days since last release), supports modern Python versions (3.10–3.13), carries no known vulnerabilities, and solves a real problem—detecting dead code and AI-generated mistakes before merge—across 12 languages in a single tool. Low install friction and permissive licensing make it a low-risk addition to a development workflow. Install it if you need multi-language static analysis, AI-code verification, or a unified security gate; the 19 dependencies are justified by broad language support and polished CLI experience.

## Install

pip install skylos
uv add skylos
poetry add skylos

## Installing skylos

Before you install: Low install friction with a pure-Python wheel. Actively maintained—last commit 2026-08-14, released 5 days ago. Supports Python 3.10–3.13. Carries 19 runtime dependencies including tree-sitter language parsers, rich for terminal output, and textual for interactive UI, which adds complexity but enables broad language support and polished CLI experience.

License in practice: Apache-2.0 permissive license allows commercial and private use, modification, and distribution with minimal restrictions—suitable for most development workflows.

Quickstart:

pip install skylos
skylos .

# For all checks (security, secrets, quality, AI defects):
skylos . -a

# Verify specific file range:
skylos verify . --file src/app.py --range 40:75

Requires Python 3.10 or later. Tree-sitter language parsers are vendored; no system compilation needed, but initial run downloads language grammars.

Verify before relying:

- Whether tree-sitter grammar downloads happen on first run and their size/time impact
- Performance characteristics on large codebases (the fact sheet mentions benchmarks but does not provide numbers)
- Exact coverage and false-positive rates for each language's AI-defect checks

## Package facts

- License: Apache-2.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 173.7K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

dead code detection, static analysis multi-language, security vulnerability scanner, ai-generated code verification, secrets detection, code quality gate, ci/cd security linter, multi-language-sast, ai-code-verification, dead-code-detection

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