Chain Builder

Build the complete, correctly ordered certificate chain for a server or file, finding missing intermediates, as PEM or .p7b.

Servers must send their certificate and the intermediate certificates that link it to a trusted root. Leave an intermediate out and browsers on some devices, plus most mail clients, Java apps, curl and Android, fail with "unable to get local issuer certificate". This builds the complete, correctly ordered chain for a server or a certificate file, finding missing intermediates the way clients do, and gives you the exact file each server type expects.