Testing TLS/SSL encryption anywhere on any port

The 'jsrsasign' (RSA-Sign JavaScript Library) is an opensource free cryptography library supporting RSA/RSAPSS/ECDSA/DSA signing/validation, ASN.1, PKCS#1/5/8 private/public key, X.509 certificate, CRL, OCSP, CMS SignedData, TimeStamp, CAdES and JSON Web Signature/Token in pure JavaScript.

PKI.js is a pure JavaScript library implementing the formats that are used in PKI applications (signing, encryption, certificate requests, OCSP and TSP requests/responses). It is built on WebCrypto (Web Cryptography API) and requires no plug-ins.

Python ASN.1 library with a focus on performance and a pythonic API

The Dogtag Certificate System is an enterprise-class Certificate Authority (CA) which supports all aspects of certificate lifecycle management, including key archival, OCSP and smartcard management.

XiPKI: Compact open source PKI (CA, OCSP responder, certificate protocols ACME, CMP, EST).

⭐ Приложение-сервер для работы с Электронно Цифровой Подписью (ЭЦП) РК

Django app providing a Certificate Authority

wolfSSL JSSE provider and JNI wrapper for SSL/TLS, supporting up to TLS 1.3!

Easy-to-use high-level library for PKI-enabled applications

Sockets with pure VB6 impl of TLS encryption

Something could be public patches

“Safest, Fastest, Easiest, and Most advanced” Python HTTP Client. Production Ready! Drop-in replacement for Requests. HTTP/1.1, HTTP/2, and HTTP/3 supported. With WebSocket!

OCSP responder for Hashicorp Vault PKI

NodePKI is a simple NodeJS based PKI manager for small corporate environments.

OCSP Server for Google Cloud Certificate Service

OCSP responder written in Go meant to be used with easy-rsa

SCEPman | Cloud-based Certification Authority

http://testssl.sh/ in a tiny docker container