Nuclei

Nuclei is a free, open-source vulnerability scanner for applications, infrastructure, cloud platforms and networks. It uses YAML templates to define checks, drawing on more than 6,500 community-contributed templates; users can also create custom templates. Scanning supports bulk and parallel runs, multiple target formats, and inclusion and exclusion filters. Modules cover HTTP, DNS, TCP, headless, JavaScript, code and file checks. Authentication options include HTTP basic and JWT. Teams can run Nuclei in CI/CD workflows, including with GitHub Actions, and export SARIF results to GitHub Code Scanning. It is distributed under the MIT License and is primarily intended as a standalone CLI tool. Installation options include Go, Homebrew, Docker, GitHub, downloadable binaries and Helm. The maker says public templates are reviewed and signed, and checks them for non-destructive, read-only requests and independent validation before merge. Some templates can fuzz or take actions that risk denial of service; those are tagged and excluded from default scans. Nuclei has no LTS or stable version, so breaking changes may occur during active development.

Nuclei offers a broad template-based scanning toolkit at no cost, with integrations for CI/CD workflows. Its active development and potentially disruptive templates are important considerations when selecting checks and planning updates.

Nuclei is suited to security engineers, analysts, red teams, DevOps teams, bug bounty hunters and penetration testers who need template-based scanning or CI/CD security checks.

Overview

Nuclei is a template-driven vulnerability scanner for security practitioners who want to define and automate checks across applications, infrastructure, cloud platforms, and networks. It is a strong fit for technical teams comfortable with a command-line tool; teams needing a stable, service-oriented scanner should look elsewhere.

Key features

Users can run community YAML templates or write their own, making checks adaptable rather than fixed. The library exceeds 6,500 community-contributed templates, and public templates are reviewed, signed, and checked for read-only requests and independent validation before distribution. These safeguards are useful, but not a substitute for care: some templates can fuzz or take actions that may cause denial of service. They are tagged and excluded from default scans, so users should still review what they enable and the targets they include.

Bulk and parallel scanning, multiple target formats, and inclusion and exclusion filters help teams manage broad scans and narrow their scope. Modules cover HTTP, DNS, TCP, headless, JavaScript, code, and file checks; authentication includes HTTP basic authentication and JWT. This range makes Nuclei useful beyond routine web checks, but template selection and scan configuration call for technical judgment.

For automated testing, Nuclei can run in CI/CD, including through GitHub Actions, and export SARIF results to GitHub Code Scanning. It can connect to ProjectDiscovery Cloud Platform to view scans. These integrations suit teams that want checks in development workflows; they do not change Nuclei’s primary role as a standalone CLI tool.

Installation options include Go, Homebrew, Docker, GitHub, downloadable binaries, and Helm. The tool is actively maintained and generally releases every two weeks, but it has no stable or LTS version, and breaking changes can occur. That pace may suit teams willing to keep up with changes; it is a drawback for workflows that depend on long-term version stability. The maker also warns that deploying Nuclei as a service may pose security risks.

Pricing

Nuclei CLI costs nothing. The plan is an open-source CLI under the MIT License, intended primarily as a standalone tool, with on-premise deployment. Authenticated scans, scheduled scans, compliance reports, and API scanning are included. There are no paid tiers or quotas described, making it a practical option for teams seeking a free scanner they can run in their own environment; its command-line focus and active development remain important trade-offs.

Platforms

Nuclei supports Linux, macOS, and Windows, and can be self-hosted. The range of installation methods accommodates different technical environments, while the CLI format is best suited to users comfortable managing tools and scan workflows themselves.

Who it's for

ProjectDiscovery names security engineers and analysts, red teams, DevOps teams, bug bounty hunters, and penetration testers as intended users. It is particularly well suited to teams that need customizable checks or want to incorporate security scanning into CI/CD. Users looking for a turnkey service or a stable release track may be better served elsewhere.

Pros and cons

• Pros: More than 6,500 community templates and the ability to create custom checks provide broad, adaptable coverage.
• Pros: CI/CD integration and SARIF export support automated testing and GitHub Code Scanning workflows.
• Pros: The MIT-licensed CLI is free and supports on-premise use.
• Cons: Some templates can disrupt targets, so users need to assess scan scope and enabled checks despite the review process and default exclusions.
• Cons: No stable or LTS version means breaking changes may affect workflows during active development.
• Cons: Its standalone CLI orientation makes it less suitable for teams seeking a service-first scanner.

Alternatives

For another free, open-source scanner with Linux, macOS, Windows, and self-hosted support, consider OWASP ZAP. Wapiti is another free, open-source option for those same platforms.

Teams wanting a freemium or paid alternative can compare ImmuniWeb, Beagle Security, Detectify Surface Monitoring, Qualys External Attack Surface Management, ZeroThreat, and Pentest-Tools.com API Scanner.

Browse Web Application Security Scanners, Vulnerability Scanning Software, and Network Vulnerability Scanners to compare more options by category.

Verdict

Choose Nuclei if your security or DevOps team wants a free, highly customizable scanner that can bring checks into CI/CD. Its expansive template ecosystem is the central advantage; the need to manage potentially disruptive checks and accommodate breaking changes is the clearest reason to look elsewhere.