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Nuclei was primarily built as a CLI tool, but with the increasing demand from users wanting to use Nuclei as a library in their own automation, a simplified Library/SDK was added in v3. The Nuclei SDK allows you to embed the complete vulnerability scanning engine into your Go applications, giving you full programmatic control over template execution, target management, and result handling.

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Key features

The Nuclei SDK provides:
  • Two execution modes: Standard single-instance mode and thread-safe mode for concurrent scanning
  • Flexible template loading: Load templates from local files, directories, or remote sources
  • Advanced filtering: Filter templates by severity, tags, protocol types, authors, and more
  • Custom callbacks: Process scan results in real-time with custom callback functions
  • Full configuration: Control concurrency, rate limiting, network settings, and more
  • Protocol support: HTTP, DNS, TCP, SSL, WebSocket, WHOIS, JavaScript, and Code protocols

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Quick start

Here’s a minimal example to get started: 
package main

import (
	nuclei "github.com/projectdiscovery/nuclei/v3/lib"
)

func main() {
	// Create nuclei engine with options
	ne, err := nuclei.NewNucleiEngine(
		nuclei.WithTemplateFilters(nuclei.TemplateFilters{Severity: "critical"}),
	)
	if err != nil {
		panic(err)
	}
	defer ne.Close()

	// Load targets
	ne.LoadTargets([]string{"scanme.sh"}, false)

	// Execute with callback
	err = ne.ExecuteWithCallback(nil)
	if err != nil {
		panic(err)
	}
}

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Execution modes

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Single instance mode

Best for sequential scanning or simple automation: 
ne, err := nuclei.NewNucleiEngine(
	nuclei.WithTemplateFilters(nuclei.TemplateFilters{Tags: []string{"cve"}}),
)

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Thread-safe mode

Best for concurrent scanning with goroutines: 
ne, err := nuclei.NewThreadSafeNucleiEngine()
if err != nil {
	panic(err)
}

// Run multiple scans concurrently
go func() {
	err = ne.ExecuteNucleiWithOpts([]string{"target1.com"},
		nuclei.WithTemplateFilters(nuclei.TemplateFilters{ProtocolTypes: "http"}),
	)
}()

go func() {
	err = ne.ExecuteNucleiWithOpts([]string{"target2.com"},
		nuclei.WithTemplateFilters(nuclei.TemplateFilters{ProtocolTypes: "dns"}),
	)
}()

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Common use cases

CI/CD integration

Integrate security scanning into your build pipelines

Custom automation

Build custom security automation workflows

Bug bounty tools

Create specialized tooling for bug bounty hunting

Security platforms

Embed vulnerability scanning in security platforms

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Architecture

The Nuclei SDK consists of several core components:
  • NucleiEngine: Main engine instance that orchestrates scanning
  • Template loader: Loads and compiles templates based on filters
  • Input provider: Manages target URLs/domains/IPs
  • Executor: Executes templates against targets
  • Output writer: Handles scan results and callbacks

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Important considerations

This project is in active development. Expect breaking changes with releases. Review the release changelog before updating.
Nuclei was primarily built to be used as a standalone CLI tool. Running Nuclei as a service may pose security risks. It’s recommended to use with caution and additional security measures.

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Next steps

Installation

Install the Nuclei SDK in your Go project

Basic usage

Learn the fundamentals with examples

API reference

Explore the complete API documentation

Advanced patterns

Master advanced scanning techniques

Build docs developers (and LLMs) love

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