This will contain the most useful tips and tricks from Hussain stream with Nahamsec which i find one of the best stream as Hussein are sharing too much valuable information for bug bounty hunters ;)
- https://bounty.offensiveai.com (it provide data of all subdomains)
- https://www.venkon.us/subdomain-lister/ (very fast subdomain discoverer)
- https://suip.biz/?act-finalrecon (free online OSINT tool)