I built a browser-based X.509 certificate chain builder (no dependencies, pure Web Crypto API)

The Problem Every time I needed to debug a certificate chain issue, I ended up juggling openssl verify , openssl x509 -text , and manually cross-referencing DNs. It works, but visualizing how a Root CA → Intermediate CA → Leaf chain fits together is painful without a GUI. Existing online tools either require uploading your cert to a server (not great for sensitive certs) or are too simplistic to handle real chain scenarios. So I built x509Lab — a browser-based X.509 certificate chain builder and verifier that runs 100% client-side. 👉 Live demo: https://x509lab.vercel.app What it does Visual Chain Builder Drag-and-drop tree UI to compose Root CA → Intermediate CA → Leaf chains. You can also model Cross-Certificate relationships. Each node is a certificate you either upload or generate on the spot. Certificate Upload & Parsing Upload PEM, DER, CRT, or CER files. The tool parses them and slots them into the tree. Subject/Issuer DN, validity period, key usage, and public key algorithm are