Snyk is an application security platform for dependencies, containers, infrastructure as code, and source code. It combines its own vulnerability intelligence with CI, repository, and enterprise integrations.

Skylos is a local-first, open-source static analysis tool. Python has the deepest coverage. TypeScript/JavaScript and Java also get dead-code, security and quality checks; PHP, Rust and Dart get dead-code and security checks. Go dead-code and security checks need the separately built skylos-go engine, which the Docker image and GitHub Action include but the PyPI package does not. C# support is partial, Kotlin is dead code only, C++ is limited to unused file-local functions, and Shell is security only. It also checks CI and deployment configuration. It combines security scanning, repository-level dead code analysis, dependency CVE checks, and AI-specific change review. Core static analysis runs locally without signup.

These tools solve overlapping but different problems. This page is an honest comparison of where each one is stronger and where they complement each other.

The short version

SnykSkylos
Best forBroad SCA, container, IaC, and enterprise AppSec workflowsLocal-first repository analysis, unused-code liveness, and changed-code guardrails
LanguagesBroad language coverage across productsPython (deepest), TypeScript/JavaScript and Java: dead code, security and quality. PHP, Rust, Dart: dead code and security. Go: dead code and security need the separate skylos-go engine (in the Docker image and GitHub Action, not the PyPI package). C# partial. Kotlin: dead code only. C++: unused file-local functions only. Shell: security only.
Dependency scanning (SCA)Yes, with broad ecosystem and vulnerability-intelligence coverageYes, OSV-backed: uv.lock, poetry.lock, Pipfile.lock, package-lock.json/npm-shrinkwrap.json, pnpm-lock.yaml, yarn.lock, plus exact pins in Python, npm, Go and NuGet manifests; declared-license policy and CycloneDX/SPDX SBOM export
Container scanningYes, including image and base-image analysisNo native image scanner: skylos image scan runs an installed Trivy on digest-pinned images and skylos ingest trivy imports Trivy reports; also checks Dockerfiles and selected deployment configuration
IaC scanningYes (including Terraform, CloudFormation, Kubernetes, and ARM)Selected Docker, Compose, Kubernetes, and CI configuration checks; no general Terraform engine
Source code SASTYes (Snyk Code)Yes; rule and data-flow depth varies by language
Dead code detectionSome coding and dead-branch issues in Snyk CodeDedicated unused-symbol graph with framework liveness and transitive propagation
Changed-code security reviewPR checks and agentic security scansDiff-aware checks for removed controls and changed-line regressions
AI and agent securitySnyk Studio (MCP), AIBOM, Evo AI-SPM, Agent Scan and Agent Guard, and Evo Agentic Development Security (GA since 2026-06-29)Local skylos done checks on an agent's branch (deleted or skipped tests, loosened CI test steps, silenced checks), agent-loop hooks for Claude Code, Codex and Cursor, git-based AI attribution, and defend checks for LLM apps
Code quality analysisSelected coding issues in Snyk CodeComplexity, coupling, cohesion, duplication, and maintainability rules
Framework awarenessRule-dependentBuilt-in (Django, Flask, FastAPI, Pydantic, pytest)
MCP serverYes, through Snyk StudioYes: skylos mcp runs locally; without a Skylos Cloud API key only the dead-code analyze tool (5 calls a day)
DeploymentSaaS by default; a deprecated Local Engine remains for existing customersCore scan is local; Cloud uploads, AI providers, and OSV lookups are explicit networked features
PricingFree / Team (starting at $25/month, for teams of up to 10 developers) / Enterprise (credit-based platform subscription; contact sales)CLI free (Apache-2.0). Skylos Cloud: Free plan (1 project) and Workspace plan, turned on for good by any one-time credit pack; no seats or subscriptions.
CI/CD setupGuided onboarding and integrationsskylos cicd init generates a GitHub Actions PR gate (--no-upload without Skylos Cloud)

Where Snyk is stronger

Dependency scanning (SCA)

Dependency and supply-chain analysis is one of Snyk's central product areas.

Snyk maintains its own vulnerability intelligence and supports a much broader set of package managers and enterprise dependency workflows. When you run snyk test, it analyzes supported dependency manifests and lockfiles for known vulnerabilities and license issues.

Skylos provides OSV-backed SCA for exact versions. It reads uv.lock, poetry.lock, Pipfile.lock, package-lock.json/npm-shrinkwrap.json, pnpm-lock.yaml and yarn.lock, plus exact entries in requirements.txt, pyproject.toml, package.json, go.mod and direct NuGet pins. It can enforce a declared-license policy (SKY-SCA-LIC001) and export CycloneDX or SPDX SBOMs (skylos sbom). It does not resolve manifest ranges, cover every package manager, or maintain a proprietary vulnerability database. Snyk remains the stronger choice when broad software-composition coverage is the main requirement.

Container scanning

Snyk Container scans Docker images, identifies vulnerable base image layers, and recommends safer base images. Skylos has no image scanner of its own: skylos image scan IMAGE@sha256:… --platform os/arch runs an installed Trivy on a digest-pinned image, and skylos ingest trivy imports existing Trivy reports. It does not recommend base-image upgrades.

If you ship containers, Snyk Container is genuinely useful; Skylos's Trivy wrapper does not replace its base-image guidance.

Infrastructure as Code scanning

Snyk IaC scans Terraform, CloudFormation, Kubernetes manifests, and ARM templates for misconfigurations. Skylos checks selected Docker, Compose, Kubernetes, CI, and deployment patterns, but it does not provide a general Terraform, CloudFormation, or ARM analysis engine.

Multi-language support

Snyk documents broad language coverage across its products. If your organization has Java, .NET, Ruby, and Python services, Snyk can provide one security platform across them.

Skylos's language coverage is tiered (see the Languages row above); Kotlin and C++ have no security rules. Snyk provides broader and more mature coverage across its product suite, especially when one program must cover many ecosystems consistently.

Enterprise features

Snyk offers team management, RBAC, SSO/SAML, Jira integration, compliance reporting, and priority scoring across an organization's portfolio. Those features are designed for formal AppSec programs.

Skylos Cloud now has workspace roles, team workflows, policy and exception governance, audit activity, and compliance reports. Teams, exception approvals and audit exports need the Workspace plan, and compliance reports also cost credits. It still does not match the breadth of Snyk's enterprise platform, SSO options, risk portfolio, or integration ecosystem.

Vulnerability database depth

Snyk's vulnerability intelligence is maintained by a dedicated security research team and adds proprietary research to its package coverage.

Skylos queries the public OSV service for supported dependency inventories. That is useful for local and CI checks, but it is narrower than Snyk's package-manager coverage, proprietary research, license analysis, and supply-chain platform.

Where Skylos is stronger

Dead code detection

Snyk Code documents some coding issues, including dead code and predefined branches. Skylos puts more emphasis on repository-wide unused-symbol reasoning: definitions, imports, callers, framework entrypoints, and transitive liveness are part of the main scan result.

Skylos detects unused functions, classes, imports, variables, and parameters. It also performs transitive dead code propagation: if function A is dead and it is the only caller of function B, Skylos marks B as dead too.

def process_legacy_order(order_id):       # dead -- nothing calls this
    validated = _validate_order(order_id)  # also dead (transitive)
    _notify_warehouse(validated)           # also dead (transitive)

Dead code is not just a quality concern. Code that is no longer reachable can still distract reviewers and retain obsolete dependencies or security-sensitive logic. Teams should compare both tools on their own frameworks because the products define and report dead code differently.

Diff-aware AI regression detection

One relevant difference for teams using AI coding assistants is changed-code regression detection.

A broad refactor can silently remove a security control. An @login_required decorator disappears, a CSRF check gets dropped, or rate limiting is removed during a cleanup.

Snyk provides PR checks and agentic security scans for issues in proposed code. Its public Snyk Code documentation does not describe the same removed-control contracts Skylos uses to compare a trusted base revision with the checked-out change.

Skylos recognizes supported patterns grouped into 11 control types when they disappear or are weakened in a diff:

  • Authentication checks and decorators
  • CSRF protection
  • TLS verification
  • Cryptographic downgrades
  • Rate limiting
  • Input validation
  • Security headers and related middleware
  • Encryption calls or key setup
  • Audit logging
  • Output sanitization
  • Permission checks
skylos . --diff-base origin/main --quality

This catches a specific regression class that current-state scanning can miss: an existing control disappearing during refactoring.

AI provenance tracking

Skylos uses git commit authors, co-author trailers, and commit-message evidence to estimate whether changed code came from a person or a named coding agent. It reports confidence because repositories do not always preserve that evidence.

Snyk offers AIBOM and agent-security capabilities. Skylos's narrower provenance workflow uses git evidence to label changed files and findings as human- or AI-authored when that evidence is available; low-confidence attribution remains visible as uncertain.

AI defense scanning (LLM application security)

If you are building applications that integrate LLMs (calling OpenAI, Anthropic, or running RAG pipelines), Skylos has dedicated scanning for LLM-specific risks:

skylos defend .

This runs the applicable checks from a 13-plugin guardrail set, with selected mappings to OWASP LLM and agentic-risk categories:

  • Raw input reaching prompt construction without intermediate processing
  • Missing delimiters around user or retrieved RAG context
  • Output PII filtering
  • Cost controls
  • Rate limiting on LLM calls

Snyk now has Snyk Studio and additional agent-security products. Skylos's defend command is a narrower local static check that emits an evidence report for guardrails around LLM calls, RAG pipelines, agents, and MCP tools.

Local-first core analysis

Snyk Code is primarily delivered as a cloud service. Snyk documents a no-code-upload Local Engine for existing customers, but that engine is deprecated and Snyk is not onboarding new customers to it.

Skylos core static analysis runs locally. Source is not uploaded unless a user chooses a networked workflow. Cloud reports may include findings, paths, line numbers, and optional snippets; configured AI providers may receive selected context; SCA sends package names, ecosystems, and exact versions to OSV, not source code.

Open source and free

Skylos is Apache 2.0 licensed. Its local CLI scans, dead code analysis, AI defense checks, and CI workflow generation have no per-scan quota. Optional Cloud and LLM-powered workflows are separate services.

Snyk's Free plan includes 200 Open Source, 100 Code, 300 IaC and 100 Container tests per month across 5 projects. Team starts at $25 a month for teams of up to 10 developers, and Enterprise is a credit-based platform subscription.

For individuals, small teams, and open-source projects, the cost difference is significant.

Local verification and MCP workflows

Skylos includes an MCP (Model Context Protocol) server that lets compatible AI agents invoke its analysis workflows:

skylos mcp

The MCP server (skylos mcp) runs on your machine. Without a Skylos Cloud API key it exposes only the dead-code analyze tool, limited to 5 calls a day; the security, quality and other tools need SKYLOS_API_KEY.

Snyk also provides an MCP server through Snyk Studio. The difference is scope and deployment: Snyk exposes its broader security platform to agents, while Skylos exposes its local repository scan, change verification, and guardrail evidence workflows.

Framework-aware analysis

Snyk Code's SAST capabilities depend on the rules available for your framework. Coverage varies.

Skylos has built-in framework visitors for Django, Flask, FastAPI, Pydantic, pytest, Celery, and Click. It understands that @app.route handlers are called via HTTP, @pytest.fixture functions are called by the test runner, and Pydantic model_validator methods are called during validation.

These visitors keep recognized framework entry points from being reported as unused without extra configuration:

@app.route("/api/users")        # Skylos: alive (Flask route handler)
def get_users():
    return jsonify(users)

@pytest.fixture
def db():                        # Skylos: alive (pytest fixture)
    return create_engine()

Generated CI/CD setup

skylos cicd init --no-upload

skylos cicd init writes a GitHub Actions pull-request gate with PR scanning, annotations and a quality gate, and needs no Skylos account or API key. By default it also adds a "Skylos Cloud upload" job for pushes to your default branch, which fails until the Skylos GitHub App is installed on the repository. Without Cloud, run skylos cicd init --no-upload.

A Snyk CLI or GitHub Action scan requires a Snyk account and token. Repository integration and monitored-project setup depend on the Snyk workflow a team chooses.

Detection comparison: what each tool catches

Known dependency vulnerabilities

Snyk: Yes. This is what Snyk does best.

snyk test
# Illustrative only: reports known vulnerabilities in your dependencies

Skylos: Yes, for supported dependency inventories through OSV: the lockfiles listed above plus exact versions in Python, npm, Go and NuGet manifests. It is not a replacement for Snyk's broader package, license-intelligence, container, and supply-chain coverage.

SQL injection in source code

Snyk Code:

# Snyk Code can flag this (depending on rules/language support)
query = f"SELECT * FROM users WHERE id = {user_id}"
cursor.execute(query)

Skylos:

# Skylos flags this (SKY-D211: SQL injection via taint analysis)
query = f"SELECT * FROM users WHERE id = {request.args['id']}"
cursor.execute(query)

# Skylos does NOT flag this (hardcoded, not user-controlled)
cursor.execute("SELECT * FROM users WHERE active = 1")

Both tools can catch SQL injection in source code. In this direct example, Skylos propagates the recognized request value through local expressions and does not add a tainted-SQL finding for the hardcoded query. Its Python model is conservative around ordinary function parameters and does not prove an interprocedural request path.

Removed security controls

Snyk: Snyk can scan pull requests for issues in proposed code. In the public documentation reviewed for this comparison, Snyk Code does not describe an equivalent base-versus-head contract for named controls that disappeared.

Skylos:

skylos . --diff-base origin/main --quality --format json

This is useful when a team wants the CI result to identify a removed control directly, rather than relying only on whether the resulting code matches a current-state vulnerability rule. Matching results use SKY-L021, HIGH severity, and name the modeled control that disappeared.

Dead code

Snyk: Snyk Code documents selected coding issues including dead code and predefined branches.

Skylos:

skylos src/
# Illustrative, abridged output
# DEAD: process_refund() in payments.py:34 (0 references)
# DEAD: _validate_refund() in payments.py:52 (only caller is dead)
# DEAD: OldPaymentProcessor class in legacy.py:12 (0 references)

When to use Snyk

  • You need dependency scanning (SCA) across your package ecosystem
  • You need container scanning for Docker images
  • You need IaC scanning for Terraform or Kubernetes
  • You need broad, consistent multi-language coverage across an AppSec program
  • You are running a formal AppSec program with compliance requirements
  • You need enterprise features (SSO, RBAC, Jira integration, compliance dashboards)
  • Your primary concern is known CVEs in third-party packages

When to use Skylos

  • You need local-first repository analysis, especially for dynamic Python and framework-heavy code
  • You want dead code detection alongside security scanning
  • Your team uses AI coding assistants and you need to catch removed security controls
  • You are building LLM-integrated applications and need AI defense scanning
  • You want local core analysis with no signup and explicit control over Cloud, AI, and OSV network features
  • You want free, open-source local scans without a per-scan quota
  • You want a generated GitHub Actions workflow without a hosted onboarding step
  • You want an MCP server for your agents and can use a Skylos Cloud API key for the security tools

When to use both

The tools can run together when a team needs both scopes.

Use Snyk for its broad platform: package and license intelligence, container images, IaC, and enterprise AppSec management.

Use Skylos for its repository-focused workflow: unused-symbol liveness, changed-code security contracts, local quality analysis, git provenance, and local agent verification. Its SCA can provide a second OSV-backed signal for supported inventories.

Their SAST and SCA coverage overlaps, so define which result owns each gate and deduplicate findings. A combined CI setup can, for example, report:

  • Snyk: a known vulnerability in a pinned dependency
  • Skylos: a modeled auth decorator removed in this diff, plus unused-symbol candidates

This combines complementary evidence from both tools.

Quick start

Snyk

npm install -g snyk
snyk auth
snyk test
snyk code test

Skylos

pip install skylos
skylos src/ --danger --quality

Final thoughts

Snyk is a broader, more mature security platform. It covers package ecosystems, licenses, container images, IaC, and enterprise AppSec management more comprehensively than Skylos.

Skylos is more focused on local repository and pull-request analysis: framework-aware liveness, diff-aware security contracts, quality signals, agent verification, and a bounded OSV-backed dependency scan. Its language support is broader than Python, but analysis depth varies by language.

The practical recommendation is to test each tool on the exact repositories and gates you plan to enforce. Teams can use Snyk for broad AppSec coverage and Skylos for local repository evidence without treating either product as universally stronger.

Try Skylos

If you want local dead-code and security analysis plus changed-code regression checks:

pip install skylos
skylos src/ --diff-base origin/main --danger --quality

The local scan needs no signup or Skylos API key. View on PyPI | Read the docs

Snyk facts were checked on October 9, 2026 against Snyk's supported-language matrix, Snyk Code documentation, Snyk Container documentation, Snyk IaC documentation, Snyk's vulnerability-database documentation, Snyk's Local Engine notice, Snyk Studio documentation, Snyk pricing, Snyk's agent-security and Evo Agentic Development Security announcements, Skylos dependency-scanning documentation, and the Skylos MCP setup guide.

Snyk is a registered trademark of Snyk Ltd. Snyk | Skylos | Skylos Docs | Install Skylos