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projectdiscovery/subfinder · source
Snapshot 0 · 2026-11-04T12:47:25Z · Go · MIT
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Fast passive subdomain enumeration tool.
README at capture
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<img src="static/subfinder-logo.png" alt="subfinder" width="200px">
<br>
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<h4 align="center">Fast passive subdomain enumeration tool.</h4>
<p align="center">
<a href="https://goreportcard.com/report/github.com/projectdiscovery/subfinder/v2"><img src="https://goreportcard.com/badge/github.com/projectdiscovery/subfinder"></a>
<a href="https://github.com/projectdiscovery/subfinder/issues"><img src="https://img.shields.io/badge/contributions-welcome-brightgreen.svg?style=flat"></a>
<a href="https://github.com/projectdiscovery/subfinder/releases"><img src="https://img.shields.io/github/release/projectdiscovery/subfinder"></a>
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<a href="https://discord.gg/projectdiscovery"><img src="https://img.shields.io/discord/695645237418131507.svg?logo=discord"></a>
</p>
<p align="center">
<a href="#features">Features</a> •
<a href="#installation">Install</a> •
<a href="#running-subfinder">Usage</a> •
<a href="#post-installation-instructions">API Setup</a> •
<a href="#subfinder-go-library">Library</a> •
<a href="https://discord.gg/projectdiscovery">Join Discord</a>
</p>
---
`subfinder` is a subdomain discovery tool that returns valid subdomains for websites, using passive online sources. It has a simple, modular architecture and is optimized for speed. `subfinder` is built for
doing one thing only - passive subdomain enumeration, and it does that very well.
We have made it to comply with all the used passive source licenses and usage restrictions. The passive model guarantees speed and stealthiness that can be leveraged by both penetration testers and bug bounty
hunters alike.
# Features
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<img src="static/subfinder-run.png" alt="subfinder" width="700px"></a>
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- Fast and powerful resolution and wildcard elimination modules
- **Curated** passive sources to maximize results
- Multiple output formats supported (JSON, file, stdout)
- Optimized for speed and **lightweight** on resources
- **STDIN/OUT** support enables easy integration into workflows
# Usage
```sh
subfinder -h
```
This will display help for the tool. Here are all the switches it supports.
```yaml
Usage:
./subfinder [flags]
Flags:
INPUT:
-d, -domain string[] domains to find subdomains for
-dL, -list string file containing list of domains for subdomain discovery
SOURCE:
-s, -sources string[] specific sources to use for discovery (-s crtsh,github). Use -ls to display all available sources.
-recursive use only sources that can handle subdomains recursively (e.g. subdomain.domain.tld vs domain.tld)
-all use all sources for enumeration (slow)
-es, -exclude-sources string[] sources to exclude from enumeration (-es alienvault,zoomeyeapi)
FILTER:
-m, -match string[] subdomain or list of subdomain to match (file or comma separated)
-f, -filter string[] subdomain or list of subdomain to filter (file or comma separated)
-match-regex string[] regex or list of regex to match on output subdomain (cli, file)
-filter-regex string[] regex or list of regex to filter on output subdomain (cli, file)
RATE-LIMIT:
-rl, -rate-limit int maximum number of http requests to send per second
-rls value maximum number of http requests to send per second for providers in key=value format (-rls "hackertarget=10/s,shodan=15/s")
-t int number of concurrent goroutines for resolving (-active only) (default 10)
UPDATE:
-up, -update update subfinder to latest version
-duc, -disable-update-check disable automatic subfinder update check
OUTPUT:
-o, -output string file to write output to
-oJ, -json write output in JSONL format
-oD, -output-dir string directory to write output (-dL only)
-cs, -collect-sources include all sources in the output (-json only)
-oI, -ip include host IP in output (-active only)
CONFIGURATION:
-config string flag config file (default "$CONFIG/subfinder/config.yaml")
-pc, -provider-config string provider config file (default "$CONFIG/subfinder/provider-config.yaml")
-r string[] comma separated list of resolvers to use
-rL, -rlist string file containing list of resolvers to use
-nW, -active display active subdomains only
-proxy string http proxy to use with subfinder
-ei, -exclude-ip exclude IPs from the list of domains
-mr, -max-results int limit the number of results per source (0 = unlimited; honored by paginating sources)
DEBUG:
-silent show only subdomains in output
-version show version of subfinder
-v show verbose output
-nc, -no-color disable color in output
-ls, -list-sources list all available sources (-oJ for JSON)
OPTIMIZATION:
-timeout int seconds to wait before timing out (default 30)
-max-time int minutes to wait for enumeration results (default 10)
-rsr, -response-size-read int max response body size to read in bytes from passive sources (0 = unlimited)
```
## Environment Variables
Subfinder supports environment variables to specify custom paths for configuration files:
- `SUBFINDER_CONFIG` - Path to config.yaml file (overrides default `$CONFIG/subfinder/config.yaml`)
- `SUBFINDER_PROVIDER_CONFIG` - Path to provider-config.yaml file (overrides default `$CONFIG/subfinder/provider-config.yaml`)
# Installation
`subfinder` requires **go1.26.10** to install successfully. Run the following command to install the latest version:
```sh
go install -v github.com/projectdiscovery/subfinder/v2/cmd/subfinder@latest
```
Learn about more ways to install subfinder here: https://docs.projectdiscovery.io/tools/subfinder/install.
## Post Installation Instructions
`subfinder` can be used right after the installation, however many sources required API keys to work. Learn more here: https://docs.projectdiscovery.io/tools/subfinder/install#post-install-configuration.
## Running Subfinder
Learn about how to run Subfinder here: https://docs.projectdiscovery.io/tools/subfinder/running.
### Filtering results with regular expressions
`-match-regex` and `-filter-regex` take Go regular expressions, repeated or from a file (one per line), and combine with `-match` and `-filter`:
```sh
subfinder -d example.com -match-regex '^(api|web)[0-9]{1,3}\.' -filter-regex '(^|\.)dev\.'
```
## Subfinder Go library
Subfinder can also be used as library and a minimal examples of using subfinder SDK is available [here](examples/main.go)
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### Resources
- [Recon with Me !!!](https://dhiyaneshgeek.github.io/bug/bounty/2020/02/06/recon-with-me/)
# License
`subfinder` is made with 🖤 by the [projectdiscovery](https://projectdiscovery.io) team. Community contributions have made the project what it is. See
the **[THANKS.md](https://github.com/projectdiscovery/subfinder/blob/main/THANKS.md)** file for more details.
Read the usage disclaimer at [DISCLAIMER.md](https://github.com/projectdiscovery/subfinder/blob/main/DISCLAIMER.md) and [contact us](mailto:contact@projectdiscovery.io) for any API removal.