Intel

Exploits
GitHub - s0md3v/Smap: a drop-in replacement for Nmap powered by shodan.io
GitHub
💀 Sploitus | Exploits & Tools Search Engine
Sploitus_com
Offensive Security’s Exploit Database Archive
GTFOBins
https://skidsearch.net
skidsearch.net
Assets / Domains / PII
Spyse — Internet Assets Search Engine
Tools - Intelligence X
LeakIX
Home - Censys
Censys
https://www.shodan.io/dashboard
www.shodan.io
ZoomEye - Cyberspace Search Engine
Information by IP Address
Whois Lookup, Domain Availability & IP Search - DomainTools
https://securitytrails.com/dns-trails#/
securitytrails.com
http://viewdns.info
viewdns.info
DNSdumpster.com - dns recon and research, find and lookup dns records
Subdomain Finder - C99.nl
GitHub - cybertoolbank/hidend: Tool for finding website backends.
GitHub
fierce | Kali Linux Tools
Kali Linux
fierce --domain domain.yzy 
IBM X-Force Exchange
https://hypestat.com
hypestat.com
MX Lookup Tool - Check your DNS MX Records online - MxToolbox
MxToolbox
Internet Archive: Wayback Machine
Arquivo.pt - pesquise páginas do passado!
Know.  Before it matters
Canarytokens
Buckets
Public Buckets
secgron
Public Buckets by GrayhatWarfare
Fake email & SMS
Receive SMS Online | Temporary and Disposable Phone Numbers
SMAIL PRO | Temp mail - Temp Gmail - Disposable Fake Email
sonjj_com
Emkei's Fake Mailer
Spam Database Lookup / Blacklist
DNSBL Information - Spam Database Lookup
BarracudaCentral.org - Technical Insight for Security Pros
http://www.kloth.net/services/dnsbl.php
Cisco Talos Intelligence Group - Comprehensive Threat Intelligence