These are some of the useful information about ssl creations, conversion and more:

Generating CSR

openssl req -new -newkey rsa:2048 -days 365 -nodes -keyout common_name.key -out common_name.csr

Verify Signature

openssl req -in myreq.pem -noout -verify -key mykey.pem

Check Info

openssl req -in myreq.pem -noout -text

CSR Decoder

openssl req -in mycsr.csr -noout -text

CRT Decoder

openssl x509 -in certificate.crt -text -noout

Cert Key Matcher

openssl x509 -noout -modulus -in certificate.crt | openssl md5
openssl rsa -noout -modulus -in privateKey.key | openssl md5
openssl req -noout -modulus -in CSR.csr | openssl md5

Convert PEM to DER

openssl x509 -outform der -in certificate.pem -out certificate.der

Convert PEM to P7B

openssl crl2pkcs7 -nocrl -certfile certificate.cer -out certificate.p7b -certfile CACert.cer

Convert PEM to PFX

openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt -certfile CACert.crt

Convert DER to PEM

openssl x509 -inform der -in certificate.cer -out certificate.pem

Convert P7B to PEM

openssl pkcs7 -print_certs -in certificate.p7b -out certificate.cer

Convert P7B to PFX

openssl pkcs7 -print_certs -in certificate.p7b -out certificate.cer
openssl pkcs12 -export -in certificate.cer -inkey privateKey.key -out certificate.pfx -certfile CACert.cer

Convert PFX to PEM

openssl pkcs12 -in certificate.pfx -out certificate.cer -nodes