openssl s_client -connect localhost:3000 -servername localhost -showcerts

Category: Web App Development

openssl s_client -connect localhost:3000 -servername localhost -showcerts

Inspect the TLS certificate a dev server presents

Connects to the TLS listener on port 3000 and prints the full certificate chain, cipher and handshake details. The -showcerts flag dumps every certificate in the chain. Use it to debug why a local HTTPS server looks wrong. The command waits on stdin, so pipe echo to it.
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