SSL-Cert-Checker

What is it?

A small tool to check SSL certificates of a list of hosts.

Prerequisites

You need Rust. Script was developed and tested with Rust 1.87.0 - any decent version should work.

How to use

Put the hostnames you want to check in hosts.txt. Start the script with cargo run.

Result

The result is an excel compatible csv file - impress your manager ;-)

Host;Not Before;Not After;Common Name;SANs
www.heise.de:443;Jul 21 03:43:11 2025 GMT;Oct 19 03:43:10 2025 GMT;www.heise.de;www.heise.de
...

Lines with errors look like this:

Host;Not Before;Not After;Common Name;SANs
spacex.cms;-;-;-;-

Why?

I had to check a list of hosts for their SSL certificate validity. The first versions involved bash+openssl or python. OK but lousy performance.

Everybody talks about Rust and it’s awesome performance. So I decided to rewrite stuff in Rust.

The result blew my mind. I have to use Rust more often…​

License

Copyright © Volker Benders.

All rights reserved.

Licensed under the MIT License. See LICENSE in the project root for license information.