OpenSSL is a robust, commercial-grade, and full-featured toolkit for the Transport Layer Security (TLS) and Secure Sockets Layer (SSL) protocols. It is...
Best crt.sh Alternatives ranked by AI · updated Aug 2026
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crt.sh is a public Certificate Transparency search service used by security researchers and administrators to inspect certificates issued for domains. Searching certificate names can reveal subdomains that appear in publicly logged TLS certificates.
Top 6 crt.sh alternatives
Subdomain Radar is an online subdomain discovery service for security researchers, penetration testers, and domain administrators. It helps identify publicly discoverable subdomains...
Pros
- Works from a browser without installing reconnaissance tools
- Lower setup effort than command-line enumeration frameworks
- Useful for quick checks during asset discovery
Cons
- Less customizable than Amass or Subfinder
- Public-data coverage may vary by domain and source
- Provides less control over automation and output formats than CLI tools
Cert Decoder is a free web-based utility for parsing X.509 and SSL/TLS certificates into readable fields. It is aimed at developers and...
Pros
- Quickly exposes certificate fields in a readable format
- Runs in a browser without installation or account creation
- Useful for inspecting PEM-encoded certificates during troubleshooting
Cons
- Does not provide the depth of server configuration testing found in SSL Labs
- Limited automation and batch-processing capabilities
- Online certificate submission may be unsuitable for sensitive internal certificates
SecurityTrails offers a platform where you can search and monitor domain registrations, DNS records, IP history, and other cybersecurity-related data.
Pros
- Rich DNS and IP data
- Historical data tracking
Cons
- Focused more on DNS and IP data than domain investigations
Starting from $49/month
5
CyberChef
GCHQ
CyberChef is a browser-based data transformation tool for developers, analysts, and security professionals. Its visual recipe system handles encoding, decoding, parsing, compression,...
Pros
- Much broader transformation library than Boop
- Runs in a browser on nearly any operating system
- Supports chained operations through reusable recipes
Cons
- Less convenient than Boop for a native macOS scratchpad workflow
- Large interface can feel overwhelming for simple edits
- Not designed as a general-purpose text editor
6
SSL Checker
SSL Shopper
SSL Checker is a browser-based service for checking HTTPS certificate validity and server installation. It is designed for website owners and administrators...
Pros
- Very quick for basic certificate and chain checks
- Clearly identifies common installation and intermediate-certificate errors
- Requires no account, software, or security expertise for routine checks
Cons
- Much less detailed TLS analysis than SSL Server Test
- Does not offer comparable protocol, cipher, or browser grading
- Limited vulnerability assessment
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