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.
How to Generate a CSR: Step-by-Step for Any Web Server
A CSR is required to get an SSL certificate from a CA. Learn how to generate one with OpenSSL, Nginx, Apache, and IIS, and what fields to fill in.
What Is OCSP Stapling and How Does It Speed Up SSL?
OCSP stapling lets your server pre-fetch revocation status so browsers don't need to. Learn how it works and how to enable it on Nginx and Apache.
Understanding Key Usage and Extended Key Usage in SSL Certificates
Key Usage and Extended Key Usage extensions define what a certificate's key can be used for. Learn to read them and understand why they matter.
TLS 1.3 vs TLS 1.2: What Changed and Why It Matters
TLS 1.3 is faster and more secure than TLS 1.2. Learn what changed in the handshake, which cipher suites were removed, and how to check which version your server supports.
Let's Encrypt vs Paid SSL Certificates: Which Is Right for You?
Let's Encrypt provides free, automated DV certificates. Paid certificates offer OV and EV validation. Learn when to use each.
How to Renew Your SSL Certificate Without Downtime
Renewing an SSL certificate doesn't have to take your site offline. Learn the right sequence: generate a new CSR, get the new cert, install it, verify.
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.