# Subfinder Passive Subdomain Enumeration

> Subfinder is a passive subdomain discovery tool by ProjectDiscovery that finds valid subdomains for websites using curated online sources. Optimized for speed and stealth, it integrates cleanly into security reconnaissance pipelines via stdin/stdout support.

- Skill: `aibot88/subfinder-passive-subdomain-enumeration` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add aibot88/subfinder-passive-subdomain-enumeration`
- Raw SKILL.md: https://api.skillmd.com/api/skills/aibot88/subfinder-passive-subdomain-enumeration/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Product & Planning
- Author: aibot88 (https://skillmd.com/u/aibot88)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/aibot88/subfinder-passive-subdomain-enumeration

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# Subfinder Fast Passive Subdomain Enumeration Tool

Subfinder is a passive subdomain discovery tool by ProjectDiscovery that finds valid subdomains for websites using curated online sources. Optimized for speed and stealth, it integrates cleanly into security reconnaissance pipelines via stdin/stdout support.

## Prerequisites

Go 1.21+

## Installation

Choose whichever fits your setup:

1. Copy this skill folder into your local skills directory.
2. Clone the repo and symlink or copy the skill into your agent workspace.
3. Add the repo as a git submodule if you manage shared skills centrally.
4. Install it through your internal provisioning or packaging workflow.
5. Download the folder directly from GitHub and place it in your skills collection.

Install command or upstream instructions:

```
go install github.com/projectdiscovery/subfinder/v2/cmd/subfinder@latest
```

## Documentation

- https://docs.projectdiscovery.io/tools/subfinder/overview

## Source

- [Agent Skill Exchange](https://agentskillexchange.com/skills/subfinder-passive-subdomain-enumeration/)