Security tool

SSL Certificate Checker

Check whether a website's SSL/TLS certificate is valid, expired, self-signed, mismatched, or missing chain details. Use it before debugging browser warnings, failed HTTPS checks, checkout trust issues, or CDN migration problems.

Typical check: 2sNo paid API requiredHTTPS and header checksBrowser trust signalsPrioritized hardening

Run security check Browse Security

Typical time

Access

Open

Processing

Live

Intent

Security

What it checks

SSL Certificate Checker coverage

SSL Certificate Checker

Check if your website SSL certificate is valid and secure.

Trust surface

Review the browser-visible signals that affect user trust and SEO.

Misconfiguration risk

Find missing headers, expired certificates, insecure assets, or weak redirects.

Fix guidance

Map each finding to server, CDN, or application-level follow-up.

Methodology

How the result is produced

1Connects to the target domain over HTTPS and retrieves the full TLS certificate chain from the server handshake.
2Validates the certificate issuer, expiry date, key size (RSA 2048+ or ECDSA P-256+), protocol version (TLS 1.2/1.3), and Subject Alternative Names (SANs).
3Detects expired, self-signed, revoked, and wildcard certificate issues that trigger browser security warnings.

Next steps

How to act on the result

If expired: renew immediately through your CA or enable auto-renewal (Let's Encrypt, Cloudflare, AWS ACM).
If self-signed: replace with a certificate from a trusted Certificate Authority — free options include Let's Encrypt.
Upgrade from TLS 1.0/1.1 to TLS 1.2 or 1.3 — older protocols are deprecated and insecure.
Enable HSTS (Strict-Transport-Security) header to force all connections over HTTPS.
Set up certificate transparency monitoring to detect unauthorized certificates for your domain.

Interpretation

Read the result without guessing

What the result means

A valid certificate does not guarantee every HTTPS page feels secure to users.
Mixed content, redirects, hostname coverage, and CDN-origin settings can still create browser warnings.
Test the exact hostname users visit, including apex and www variants.

Evidence to keep

Response headers, certificate details, redirect chain, and browser console warning text.
The exact page URL because security behavior can differ across templates.
A list of scripts, images, frames, and third-party sources if CSP is involved.

Best next fix

Fix HTTPS reachability and mixed content first.
Add baseline headers at the CDN or edge where possible.
Use report-only testing for strict policies, then retest login, checkout, and embedded flows.

Related diagnostic workflows

SSL is valid but the browser still shows a warningA trust workflow for HTTPS pages that still look unsafe to users.Open workflow Website is down for me but not for othersA triage path for confusing uptime reports across regions, devices, and networks.Open workflow Important security headers are missingA careful hardening sequence for CSP, HSTS, X-Frame-Options, referrer policy, and related headers.Open workflow

Use cases

When to use the SSL Certificate Checker

Launch hardening

Validate HTTPS, redirects, headers, and browser-facing security before launch.

Incident triage

Quickly confirm whether a warning is caused by TLS, mixed content, or headers.

Compliance prep

Collect practical evidence before a security or privacy review.

Popular checks

Try SSL on common domains

SSL for stripe.com SSL for github.com SSL for cloudflare.com SSL for shopify.com SSL for openai.com SSL for vercel.com

Next paths

Continue with the right follow-up

Use these pages when the result points to a broader check, a fix workflow, or a related technical question.

Security Headers Explained Website Trust Signals Checklist

Fix workflows

Fix issues found by SSL

How to fix an expired SSL certificate

Resolve expired SSL certificates and prevent HTTPS trust warnings from blocking users.

Open fix guide

How to fix mixed content on HTTPS pages

Fix HTTP assets loaded on HTTPS pages to remove browser warnings and trust issues.

Open fix guide

How to fix a missing HSTS header

Add HTTP Strict Transport Security safely after HTTPS is working across all hosts.

Open fix guide

Frequently asked questions

SSL Certificate Checker common questions

Do I need an account to use the SSL Certificate Checker?+

No. Enter a URL or domain and run the check in your browser. Some results can be partial if the target site blocks requests or hides the data being checked.

How accurate is the SSL Certificate Checker?+

The SSL Certificate Checker runs live checks against the target website. Results reflect what was reachable at the time of the test, so retest after changing DNS, redirects, headers, or page content.

What happens if my SSL certificate expires?+

Browsers can show a security warning, users may abandon the page, and some crawlers or integrations may fail HTTPS requests. Renew the certificate and retest the final HTTPS URL.

How early should I renew my SSL certificate?+

Most CAs recommend renewing 30 days before expiry. Our checker flags certificates expiring within 30 days as a warning.

Does this check detect mixed content issues?+

This tool focuses on certificate validity. Use our dedicated Mixed Content Scanner to find insecure HTTP resources on HTTPS pages.

Loading CheckWebs…

Security tool

SSL Certificate Checker

Typical check: 2sNo paid API requiredHTTPS and header checksBrowser trust signalsPrioritized hardening

Run security check Browse Security

Typical time

Access

Open

Processing

Live

Intent

Security

What it checks

SSL Certificate Checker coverage

SSL Certificate Checker

Check if your website SSL certificate is valid and secure.

Trust surface

Review the browser-visible signals that affect user trust and SEO.

Misconfiguration risk

Find missing headers, expired certificates, insecure assets, or weak redirects.

Fix guidance

Map each finding to server, CDN, or application-level follow-up.

Methodology

How the result is produced

1Connects to the target domain over HTTPS and retrieves the full TLS certificate chain from the server handshake.
2Validates the certificate issuer, expiry date, key size (RSA 2048+ or ECDSA P-256+), protocol version (TLS 1.2/1.3), and Subject Alternative Names (SANs).
3Detects expired, self-signed, revoked, and wildcard certificate issues that trigger browser security warnings.

Next steps

How to act on the result

If expired: renew immediately through your CA or enable auto-renewal (Let's Encrypt, Cloudflare, AWS ACM).
If self-signed: replace with a certificate from a trusted Certificate Authority — free options include Let's Encrypt.
Upgrade from TLS 1.0/1.1 to TLS 1.2 or 1.3 — older protocols are deprecated and insecure.
Enable HSTS (Strict-Transport-Security) header to force all connections over HTTPS.
Set up certificate transparency monitoring to detect unauthorized certificates for your domain.

Interpretation

Read the result without guessing

What the result means

A valid certificate does not guarantee every HTTPS page feels secure to users.
Mixed content, redirects, hostname coverage, and CDN-origin settings can still create browser warnings.
Test the exact hostname users visit, including apex and www variants.

Evidence to keep

Response headers, certificate details, redirect chain, and browser console warning text.
The exact page URL because security behavior can differ across templates.
A list of scripts, images, frames, and third-party sources if CSP is involved.

Best next fix

Fix HTTPS reachability and mixed content first.
Add baseline headers at the CDN or edge where possible.
Use report-only testing for strict policies, then retest login, checkout, and embedded flows.

Related diagnostic workflows

Use cases

When to use the SSL Certificate Checker

Launch hardening

Validate HTTPS, redirects, headers, and browser-facing security before launch.

Incident triage

Quickly confirm whether a warning is caused by TLS, mixed content, or headers.

Compliance prep

Collect practical evidence before a security or privacy review.

Popular checks

Try SSL on common domains

SSL for stripe.com SSL for github.com SSL for cloudflare.com SSL for shopify.com SSL for openai.com SSL for vercel.com

Next paths

Continue with the right follow-up

Use these pages when the result points to a broader check, a fix workflow, or a related technical question.

Security Headers Explained Website Trust Signals Checklist

Fix workflows

Fix issues found by SSL

How to fix an expired SSL certificate

Resolve expired SSL certificates and prevent HTTPS trust warnings from blocking users.

Open fix guide

How to fix mixed content on HTTPS pages

Fix HTTP assets loaded on HTTPS pages to remove browser warnings and trust issues.

Open fix guide

How to fix a missing HSTS header

Add HTTP Strict Transport Security safely after HTTPS is working across all hosts.

Open fix guide

Frequently asked questions

SSL Certificate Checker common questions

Do I need an account to use the SSL Certificate Checker?+

No. Enter a URL or domain and run the check in your browser. Some results can be partial if the target site blocks requests or hides the data being checked.

How accurate is the SSL Certificate Checker?+

The SSL Certificate Checker runs live checks against the target website. Results reflect what was reachable at the time of the test, so retest after changing DNS, redirects, headers, or page content.

What happens if my SSL certificate expires?+

Browsers can show a security warning, users may abandon the page, and some crawlers or integrations may fail HTTPS requests. Renew the certificate and retest the final HTTPS URL.

How early should I renew my SSL certificate?+

Most CAs recommend renewing 30 days before expiry. Our checker flags certificates expiring within 30 days as a warning.

Does this check detect mixed content issues?+

This tool focuses on certificate validity. Use our dedicated Mixed Content Scanner to find insecure HTTP resources on HTTPS pages.