Open source
Nuclei
Open source scanner that runs vulnerability checks from templates
Web ScanningTemplate based vuln scanner
Alternatives to Shodan
12 tools like Shodan, chosen by what they do. About Shodan
Curated
Detectify
Cloud scanner for exposed assets, APIs and web applications
Web ScanningAttack surface scanner
Curated
StackHawk
Security testing for running apps, with fixes from coding agents
Web ScanningDeveloper first DAST
Open source
testssl.sh
Command line tool that tests TLS and SSL server configurations
Web ScanningCommand line TLS tester
Freemium
Free
Have I Been Pwned
Check if your email or password appeared in a known data breach
Web SecurityCheck for data breaches
Curated
GitGuardian
Platform that finds exposed secrets and credentials in code
Code SecuritySecrets detection at scale
Open source
Proton VPN
VPN with a free plan, open source apps and a no-logs audit
Network DefenseSwiss privacy VPN
Open source
Freemium
Burp Suite
Web security testing toolkit for manual and automated scanning
Pentest and BountyWeb security testing toolkit
Open source
Semgrep
Scans source code and dependencies for security issues
Code SecurityFast code security scanning
Curated
MXToolbox
Online DNS, mail server and blacklist lookup tools
Email and EncryptionDNS and email diagnostics