TheSeoSoul
Free tools/Technical

Free SSL Days Checker

See how many days remain on the site's TLS certificate, who issued it, and whether HTTPS redirects stay on HTTPS — free, no signup.

How it works

  1. 01

    Probe TLS on port 443

    We connect with SNI for the hostname and read the presented certificate’s not-after date.

  2. 02

    Compute days remaining

    Expiry under 21 days is flagged as a warning; expired certs fail clearly.

  3. 03

    Trace HTTPS redirects

    A short redirect trace confirms the final URL still uses HTTPS after hops.

What this TLS / SSL certificate checker inspects

  • Certificate validity window and precise days remaining
  • Certificate Authority (CA) issuer details and common names
  • SNI hostname match to prevent certificate name mismatch errors
  • End-to-end HTTPS enforcement across the full redirect path

Scenarios

TLS Expiry Pitfalls & HTTPS Scenarios

An expired SSL certificate immediately drives away 90%+ of organic traffic due to full-screen browser security warnings:

Certbot Failures

Silent Let's Encrypt Renewal Breaks

The Problem: Automated Certbot cron jobs failing silently due to HTTP-01 challenge firewall blocks, leading to 90-day certs expiring without notice.

The Fix: Monitor certificate days remaining and set proactive renewal triggers when certificates drop below 30 days.

Mixed Content

Passive & Active Mixed Content Warnings

The Problem: Loading images or scripts via insecure http:// URLs on an https:// page triggers browser 'Not Secure' warnings and blocks asset execution.

The Fix: Deploy Content-Security-Policy: upgrade-insecure-requests to auto-rewrite all asset requests to HTTPS.

Subdomain Wildcards

Hostname Mismatch (SSL_ERROR_BAD_CERT_DOMAIN)

The Problem: Using a single-domain certificate for deep subdomains (e.g. app.sub.example.com) that are not covered by a standard wildcard (*.example.com).

The Fix: Verify SAN (Subject Alternative Names) or obtain dedicated multi-domain certificates for multi-tier architectures.

Enforcing HTTPS & Upgrading Mixed Content

Ensure all visitors and assets communicate strictly over encrypted channels:

Nginx HTTP to HTTPS 301 Redirectnginx
server {
    listen 80;
    server_name example.com www.example.com;
    return 301 https://example.com$request_uri;
}
CSP Automatic HTTPS Upgrade Headertext

Force browsers to upgrade all insecure HTTP image and script links automatically:

Content-Security-Policy: upgrade-insecure-requests;

Frequently asked questions

What does the SSL days checker show?
It opens a TLS connection to the hostname, reads the peer certificate, and reports days remaining, expiry time, and issuer — plus whether HTTPS redirects land on HTTPS.
Why do certificate days matter for SEO?
Expired certificates trigger browser warnings, kill trust, and can interrupt crawling. Renew before the last 21 days so automation and humans are not surprised.
Does this validate the full certificate chain?
It reads the presented leaf certificate. Deep chain / CT / pinning audits are out of scope for this free check.
Is this free?
Yes — free, no registration on TheSeoSoul.

Keep going

What to check next

TLS is table stakes — check headers and crawl discovery next.

Need the whole picture? Run a full audit · browse every tool.