SSL Certificate Articles
In-depth guides on SSL/TLS certificates — how they work, how to read them, common errors, and best practices.
Written for developers and sysadmins who deal with certificates day-to-day: deploying them, debugging errors, choosing the right type, and understanding what a CA actually does when it signs your CSR.
Certificate Transparency Logs: How They Keep the Web Safer
Certificate Transparency logs are public records of every SSL certificate issued. Learn how they work, why they exist, and how to search them.
Why Your SSL Certificate's Expiry Date Matters More Than You Think
An expired SSL certificate takes your site offline instantly. Learn why expiry happens, how to monitor it, and what to do when a certificate expires.
How to Fix a Hostname Mismatch Error
A hostname mismatch error means the domain in your browser doesn't match any name on the SSL certificate. Here's how to diagnose and fix it.
PEM vs DER: SSL Certificate File Formats Explained
PEM and DER are the two main certificate file formats. Learn the difference, when to use each, and how to convert between them.
What Is OCSP and Why Does It Matter for SSL?
OCSP lets browsers check in real time whether an SSL certificate has been revoked. Learn how it works, its limitations, and how OCSP stapling improves it.
Subject Alternative Names: Protecting Multiple Domains with One Certificate
SANs let one SSL certificate cover dozens of domains. Learn how Subject Alternative Names work, how to read them, and how they replaced the Common Name.
How Certificate Fingerprints Work and Why They Matter
A certificate fingerprint is a unique hash of the certificate's bytes. Learn how SHA-256 and SHA-1 fingerprints are computed and when to use them.
Understanding Certificate Chains: Root, Intermediate, and Leaf
Learn how the certificate chain of trust works — from the leaf certificate on your server up through intermediates to a root CA your browser trusts.
DV vs OV vs EV: Choosing the Right SSL Certificate Type
Compare Domain Validation, Organization Validation, and Extended Validation SSL certificates. Learn which type fits your site's needs and budget.
How to Read an SSL Certificate: Every Field Explained
Not sure what all those fields in an SSL certificate mean? This guide walks through every field — CN, SANs, fingerprint, key usage — in plain English.
What Is an SSL Certificate? A Plain-English Explainer
SSL certificates encrypt the connection between your browser and a web server. Learn what they are, how they work, and why every site needs one.