September 6, 2026

How to Configure Subfinder with API Keys for Better Passive Subdomain Enumeration

Subfinder is a passive subdomain enumeration tool developed by ProjectDiscovery.

By MaMad

It collects subdomains from different public sources and APIs such as Chaos, DNSDumpster, FOFA, Netlas.io, SecurityTrails, Shodan, VirusTotal, WhoisXMLApi, ZoomEye and many other sources.

In this guide, we'll configure Subfinder with API keys to improve passive subdomain enumeration.

🔧 Setup

Subfinder uses a default configuration file for API keys:

~/.config/subfinder/provider-config.yaml

You can configure your API keys inside this file.

If you want to use a custom configuration file, you can specify its path with the -config flag:

subfinder -config /path/to/provider-config.yaml

🔑 Configure API Keys

  1. Open the configuration file:
nano ~/.config/subfinder/provider-config.yaml
  1. Then add your API keys under the corresponding providers.

For example:

bevigil: []
binaryedge: []
bufferover: []
builtwith: []
c99: []
censys: []
certspotter: []
chaos: []
chinaz: []
digitalyama: []
dnsdb: []
dnsdumpster: []
dnsrepo: []
facebook: []
fofa: []
fullhunt: []
github: []
hunter: []
intelx: []
leakix: []
netlas: []
quake: []
redhuntlabs: []
robtex: []
securitytrails: []
shodan: []
threatbook: []
virustotal: []
whoisxmlapi: []
zoomeyeapi: []

Replace the empty values with your own API keys where required.

You don't need to configure every provider. Add the sources you have access to and want to use.

Important:_ Never publish your real API keys in a public repository, screenshot, or article._

Now, See the difference in the results. 👌