SSL Checker

Check SSL certificate details for any domain. Verify issuer, validity period, days until expiry, Subject Alternative Names, and certificate chain. Free, instant, no API key needed.

Enter a domain and click Check SSL.

Manual SSL Check via Browser DevTools

You can also check SSL certificates directly in your browser:

  1. Open the website you want to check (e.g., https://example.com)
  2. Click the padlock icon in the address bar
  3. Click "Connection is secure" or "Certificate"
  4. Click the certificate details to view issuer, validity, and SANs

About SSL Checker Tool

Verify SSL/TLS certificate configuration for any domain. Check certificate issuer, validity period, days until expiry, Subject Alternative Names (SANs), and certificate chain. Identify expired or misconfigured certificates before they cause issues for your users.

Certificate Details

View issuer, subject, validity dates, and serial number. All essential certificate information presented in a clean, readable format.

Expiry Monitoring

See exactly how many days remain until the certificate expires. Color-coded indicators warn you when expiration is approaching (red for expired, yellow for near expiry).

SAN Coverage

View all Subject Alternative Names (SANs) listed on the certificate. Ensure all your domains are properly covered by the certificate.

No API Key Required

Uses publicly available certificate transparency data and chain-of-trust verification. No registration, no API key, no rate limits.

📋 Common Use Cases

Pre-Commit Checking

Validate JSON, HTML, or other structured data before committing to your repository. Prevent broken configs from reaching production.

API Response Verification

Validate JSON responses from your API endpoints during development and testing. Ensure your data contracts are well-formed.

Configuration Debugging

Find syntax errors in JSON configuration files, package.json, or manifest files. Get line-level error details for quick fixes.

Code Quality Assurance

Validate HTML for accessibility and standards compliance. Catch missing tags, invalid attributes, and structural issues.

🪜 How to Use This Tool

  1. Paste code or data to validate
    Enter JSON, HTML, or other structured text into the input area. Syntax errors are highlighted in real time.
  2. Review error details
    See line numbers, column positions, and descriptions for each issue. Click errors to jump to the problematic location.
  3. Fix and revalidate
    Edit in place and see validation results update automatically. Iterate until your code is clean.
  4. Copy validated code
    Once valid, copy the code for use in your project. Some validators also format/beautify the output.

📚 Related Guides

Frequently Asked Questions

Are these dev tools free?▼
Yes. All dev tools are completely free. No signup, no account.
Is my data sent to a server?▼
No. Base64 encoding, URL encoding, JWT decoding, hash generation, and regex testing all happen in your browser. Your tokens and secrets stay on your device.
Can I decode JWTs safely?▼
Yes. JWT decoding happens entirely in your browser. The token never leaves your device. Only the header and payload are decoded — signatures are not verified server-side.