Nuclei review 2026: ProjectDiscovery's open-source, template-based vulnerability scanner. See features, YAML DSL scanning, pricing and top alternatives.
Nuclei is an open-source vulnerability scanner developed by ProjectDiscovery, a San Francisco-based cybersecurity company founded in 2019. Unlike traditional scanners with hardcoded detection logic, Nuclei runs configurable, community-authored templates written in a simple YAML-based domain-specific language, letting the security community add and update checks continuously.
The project has become one of the most widely used open-source scanners in security testing, processing over 50 million scans a month across more than 100 countries, and is frequently used in penetration testing, bug bounty hunting and continuous attack-surface monitoring.
Nuclei's core strength is its template-based architecture: each vulnerability check, misconfiguration or exposure signature is defined declaratively in YAML rather than compiled into the tool itself, so new checks for freshly disclosed CVEs can ship within hours through the public template repository.
Built in Go for speed, Nuclei supports high-concurrency scanning across large target lists and covers web applications, APIs, DNS, network services and cloud misconfigurations. It is designed to be scripted into CI/CD pipelines and automation workflows rather than run only as a manual, interactive tool.
Nuclei itself is completely free and open source, with no paywalled features or usage limits when self-hosted and run from the command line or CI pipeline.
ProjectDiscovery monetizes separately through the ProjectDiscovery Cloud Platform, a hosted product built on top of Nuclei that adds continuous attack-surface management, team collaboration and reporting; pricing for that platform is custom and quoted directly by ProjectDiscovery's sales team.
Nuclei is used to scan web applications, APIs, networks, DNS and cloud configurations for known vulnerabilities, misconfigurations and exposures using community-maintained YAML templates.
Yes, Nuclei is completely free and open source with no paywalled features. ProjectDiscovery separately sells a hosted Cloud Platform built on top of it.
Nuclei is developed by ProjectDiscovery, a cybersecurity company founded in 2019 and headquartered in San Francisco, which has raised roughly $25 million in funding including a Series A led by CRV.
Nuclei runs configurable templates written in a YAML-based domain-specific language against a target, each template encoding a specific vulnerability check, misconfiguration signature or exposure pattern.
Yes, Nuclei is commonly integrated into CI/CD pipelines and automated security workflows to continuously scan for newly disclosed vulnerabilities.
Penetration testers, bug bounty hunters, red teams and DevSecOps engineers use Nuclei for fast, automatable vulnerability scanning.
Alternatives include Nmap with NSE scripts, OpenVAS, Burp Suite and Nessus, though Nuclei is distinguished by its lightweight YAML template model and open-source, community-driven update cadence.