Resources

Guides, tutorials, and reference articles about SSL certificates, TLS, HTTPS, and certificate monitoring.

Guides

The Complete SSL/TLS Guide

Everything you need to know about SSL/TLS certificates, from basics to advanced topics.

SSL Monitoring Guide

How to monitor SSL certificates at scale and never miss an expiry.

SSL Troubleshooting Guide

Diagnose and fix common SSL certificate errors and misconfigurations.

Knowledge Base

Why Auto-Renew Isn't Enough for SSL Certificates

Auto-renewal sounds foolproof. It isn't. Certbot failures, DNS changes, server migrations, and silent errors that leave you with an expired certificate.

How to Track SSL Certificate Expiry Dates in Bulk

Manage SSL certificate expiry dates across dozens or hundreds of certificates. Methods from scripts to dedicated monitoring tools for teams of every size.

Buying an SSL Certificate: What to Know

What to know before buying an SSL certificate: when to buy vs use free, which type you need, where to buy, and how to avoid overpaying.

Certificate Transparency Logs Explained

What Certificate Transparency is, how CT logs work, how to search them for unauthorized certificates, and why Chrome requires CT compliance for all publicly trusted certificates.

Cheap SSL Certificates: Are They Worth It?

Are cheap SSL certificates worth it? How low-cost certificates compare to expensive ones, when free is the better option, and what you actually get for the price.

What Is a Digital Certificate?

What digital certificates are, how they work, the different types (SSL, code signing, email, client), and how the public key infrastructure enables trust on the internet.

Famous SSL Certificate Expiry Disasters

Real-world SSL certificate expiry incidents at Microsoft, Spotify, LinkedIn, and more. What happened, what it cost, and how monitoring would have prevented it.

Free SSL Certificates: Your Complete Guide

Everything about free SSL certificates: Let's Encrypt, ZeroSSL, Cloudflare, and hosting providers. How free certificates work, their limitations, and when to pay.

How HTTPS Works: Step by Step for Beginners

A step-by-step explanation of how HTTPS works, from the TLS handshake to encrypted data transfer. Written for beginners with no cryptography background.

How to Check an SSL Certificate

Four ways to check any website's SSL certificate: browser inspection, online tools, command line, and monitoring. Plus a comparison of free SSL checker tools.

How to Check SSL Certificate Expiration Date

Five ways to check when an SSL certificate expires: browser, OpenSSL, online tools, cURL, and monitoring platforms. Never be surprised by an expired cert.

How to Check SSL Certificates in Your Browser

Step-by-step guide to viewing SSL certificate details in every major browser. Check expiry dates, certificate chain, and issuer without leaving your browser.

How to Check SSL Certificates with OpenSSL

OpenSSL commands for checking SSL certificates: view expiry dates, decode certificates, verify chains, and test TLS connections. Copy-paste commands included.

How to Decode an SSL Certificate

Decode SSL certificates in PEM, DER, and PKCS formats. Read certificate fields, extract SANs, check key usage, and understand the certificate structure.

How to Fix SSL Certificate Errors

Troubleshoot common SSL certificate errors: expired certificates, name mismatches, untrusted issuers, mixed content, and chain issues. Step-by-step fixes.

How to Get an SSL Certificate (Free and Paid Options)

How to get an SSL certificate for your website: free options like Let's Encrypt and Cloudflare, paid DV/OV/EV certificates, the CSR and validation process, and choosing the right option.

How to Install an SSL Certificate

Step-by-step instructions for installing an SSL certificate on Nginx, Apache, IIS, cPanel, Plesk, and Cloudflare. Plus verification with openssl and common installation errors.

How to Validate an SSL Certificate

Validate SSL certificates are correctly installed and trusted. Check chain completeness, hostname matching, protocol support, and certificate transparency.

Invalid SSL Certificate: What It Means and How to Fix It

Every reason an SSL certificate can be invalid: expired, wrong domain, self-signed, revoked, incomplete chain. Browser error messages explained and step-by-step fixes.

Using Let's Encrypt in Production: Best Practices

Best practices for running Let's Encrypt in production: Certbot configuration, renewal automation, monitoring, rate limits, and failure handling.

mTLS (Mutual TLS) Explained

What mutual TLS is, how it differs from standard TLS, how the mTLS handshake works, use cases like zero trust and service mesh, and how mTLS compares to API keys and OAuth.

Root vs Intermediate Certificates Explained

The difference between root and intermediate certificates, why the chain of trust matters, what happens when intermediate certificates are missing, and how to fix chain issues.

SAN Certificates: Multi-Domain SSL Explained

What SAN certificates are, how Subject Alternative Names work, when to use multi-domain certificates, and how they compare to wildcard certificates.

Self-Signed SSL Certificates: When to Use Them

What self-signed SSL certificates are, when they're appropriate, and when they'll cause problems. Development, testing, and internal use cases.

SSL Certificate Chain Explained

How SSL certificate chains work: root CAs, intermediate certificates, and leaf certificates. Why chain errors break your site and how to fix them.

SSL Certificate Glossary

Definitions of SSL and TLS terms: certificates, CAs, OCSP, CSR, SANs, HSTS, certificate pinning, and more. Plain-English explanations for every term.

SSL Certificate Management Strategy for Growing Teams

Build an SSL certificate management strategy: inventory, automation, monitoring, and incident response. For teams scaling from 10 to 1,000+ certificates.

SSL Certificate Pricing Explained

What SSL certificates cost, why prices vary so much, what you are paying for at each price tier, and how to avoid overpaying for certificates.

Best SSL Certificate Providers Compared

Comparison of SSL certificate providers: Let's Encrypt, DigiCert, Sectigo, GlobalSign, and GoDaddy. Pricing, validation types, warranty, and support.

SSL Certificate Renewal: Complete Process Guide

Step-by-step guide to renewing SSL certificates, covering auto-renewal with Let's Encrypt, manual renewal with commercial CAs, key rotation, common failures, and post-renewal verification.

SSL Certificate Revocation: CRL and OCSP Explained

How SSL certificate revocation works, including CRL and OCSP mechanisms, OCSP stapling, CRLite, browser soft-fail vs hard-fail behavior, and how to check revocation status.

SSL Certificate Checker Tools Compared

Comparison of the best free SSL certificate checker tools: Qualys SSL Labs, SSLShopper, DigiCert, SSL Checker, and more. Features, speed, and reliability.

SSL Definition: What SSL Means in Plain English

A plain-English definition of SSL (Secure Sockets Layer), what it means when someone says 'SSL,' and how the term is used today even though the protocol itself is obsolete.

SSL Certificate Error Code 526: Causes and Fixes

Cloudflare error 526 means the origin SSL certificate is invalid. Learn what causes it, how to diagnose it, and how to fix it step by step.

SSL Certificates for Localhost and Development

How to set up SSL certificates for localhost and local development environments. Covers mkcert, self-signed certificates, and why HTTPS matters in development.

SSL Inspection: How It Works and Security Implications

How SSL/TLS inspection works, why organizations use it, the security tradeoffs of breaking end-to-end encryption, and when it makes sense vs when it doesn't.

SSL Certificate Monitoring Explained

What SSL certificate monitoring is, why you need it, and how it works. Beyond expiry tracking: chain validation, certificate changes, and proactive alerts.

SSL Pinning Explained: What It Is and When to Use It

What SSL/certificate pinning is, how certificate and public key pinning work, why HPKP was deprecated, how mobile apps implement pinning, and when pinning helps vs hurts.

SSL Certificate Renewal Checklist

Step-by-step SSL certificate renewal checklist. From inventory to validation to deployment — never miss a renewal or break your site with a bad certificate swap.

SSL vs TLS: What's the Difference?

SSL and TLS explained: the differences between protocol versions, why SSL is deprecated, and why everyone still says 'SSL' when they mean TLS.

Types of SSL Certificates: DV, OV, and EV Explained

Domain Validation, Organization Validation, and Extended Validation SSL certificates compared. Which type you need, what they cost, and what they actually prove.

Website Security Checklist

Essential website security checklist: SSL/TLS configuration, headers, authentication, updates, backups, and monitoring. Prioritized for maximum impact.

What Happens When an SSL Certificate Expires

The full timeline of an SSL certificate expiration: browser warnings, broken APIs, SEO impact, and lost revenue. What breaks and how fast.

What Is a Certificate Authority (CA)?

What certificate authorities are, how they issue and validate SSL certificates, the trust hierarchy, major CAs, and what happens when a CA is compromised.

What Is an SSL Certificate?

What an SSL certificate is, how it works, why websites need one, the different types, and how SSL certificates secure the connection between browsers and servers.

What Is HTTPS? How SSL Secures Your Website

What HTTPS is, how it differs from HTTP, how SSL/TLS encryption secures web traffic, and why HTTPS is required for modern websites.

What Is SSL Inspection?

How SSL/TLS inspection works, why organizations use it, and the security and privacy trade-offs. Also known as TLS interception or SSL decryption.

Wildcard SSL Certificates Explained

How wildcard SSL certificates work, when to use them, their limitations, and why they can be a security risk. Plus: alternatives to wildcards.