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Reference to these tools is solely for the information and convenience of the public, and does not constitute the endorsement or recommendation of any company, product, or service by the CA/Browser Forum.

Online Tests of SSL/TLS Configurations (submit website to check)

CryptCheck – https://cryptcheck.fr / https://tls.imirhil.fr/

DigiCert – https://www.digicert.com/help/

Hardenize – https://www.hardenize.com/

Immuniweb – https://www.immuniweb.com/ssl/

Mozilla Observatory – https://observatory.mozilla.org

Scanigma – https://scanigma.com/

SSL Checker – https://www.sslchecker.com/sslchecker

SSL Labshttps://www.ssllabs.com/ssltest

SSLyze – https://github.com/nabla-c0d3/sslyze

TestSSL – https://testssl.sh/

Wormly – https://www.wormly.com/test_ssl

Browser / Client Testing

BadSSL – https://badssl.com/  (numerous scenarios to use to test how your browser reacts)

How’s My SSL – https://www.howsmyssl.com/

SSL Labs – https://clienttest.ssllabs.com:8443/ssltest/viewMyClient.html

Check for Bad Private Keys

Hanno Boeck‘s Tool – https://github.com/badkeys/badkeys

ROCA Vulnerability – https://github.com/crocs-muni/roca

CVE-2008-0166 – https://github.com/CVE-2008-0166 provides a generator that runs on modern 64-bit Linux systems and provides complete sets of pregenerated keys for the most common RSA key sizes
Debian Weak Keys – https://github.com/HARICA-official/debian-weak-keys provides a generator, for a subset of the parameters listed above, that can take advantage of a computer cluster

Check Certificates and CSRs (Searches and Decoders)

Crt.sh – https://crt.sh/?sha256=   [sha256 hash of certificate]

Censys.io – https://search.censys.io/certificates  (billions of certificates)

GoDaddy Certificate and CSR Decoders – https://ssltools.godaddy.com/views/csrDecoder / https://ssltools.godaddy.com/views/certDecoder

Mozilla Certsplainer – https://tls-observatory.services.mozilla.com/static/certsplainer.html  (Shows certificate information and shows path to root certificate (requires certificate PEM file))

Mozilla EV certificate checker – https://tls-observatory.services.mozilla.com/static/ev-checker.html (requires certificate PEM and EV OID)

Sectigo – https://secure.sectigo.com/utilities/decodeCSR.html

CA Information

Status of each CA’s three test websites

Crt.sh – https://crt.sh/test-websites

Status of CAs’ CCADB reporting compliance  

Crt.sh – https://crt.sh/mozilla-disclosures

CA Misissuance

Coming soon

Revocation Checking

Revocation Checker – https://certificate.revocationcheck.com/

Certificate Tools OCSP Checker – https://certificatetools.com/ocsp-checker

OCSP Watch – https://sslmate.com/labs/ocsp_watch/

Offline, Downloadable Tools

OpenSSL – https://www.openssl.org/

How to check OCSP using OpenSSL – https://unmitigatedrisk.com/?p=42

OWASP SSL advanced forensic tool (O-Saft) https://owasp.org/www-project-o-saft/

ASN.1 Viewers – https://www.itu.int/en/ITU-T/asn1/Pages/Tools.aspx

Mozilla SSL/TLS Configuration Generator for Servers (Apache, nginx, etc.) – https://ssl-config.mozilla.org/

SSL Labs: SSL and TLS Deployment Best Practices – https://github.com/ssllabs/research/wiki/SSL-and-TLS-Deployment-Best-Practices

OWASP TLS Cheat Sheet – https://cheatsheetseries.owasp.org/cheatsheets/Transport_Layer_Protection_Cheat_Sheet.html