📖 Description

Digital certificates are the core of the internet's trust system. Any minor error can lead to website inaccessibility or data breaches:

Prevent Website Certificate Expiration: Quickly check the remaining validity period of a server's certificate to proactively avoid the risk of browsers displaying "Your connection is not private" warnings.
Confirm Certificate Chain Integrity: Check if the server is correctly configured with intermediate CA certificates, preventing errors on some mobile devices due to missing trust chains.
Verify Private Key Matching: Before deploying a certificate, compare whether the certificate (CRT) and private key (KEY) are paired to avoid Web service (Nginx/Apache) startup failures caused by mismatched files.
Check Compliance and Algorithms: Review the certificate's signature algorithm (e.g., SHA-256) and key length (e.g., RSA 2048-bit) to ensure compliance with the latest security requirements.

This site's tool provides dual dimensions of "remote probing" and "local parsing":

One-Click Retrieval: Enter a domain name (e.g., example.com), and the tool will automatically connect and extract the SSL certificate currently in use by the server.
Information Insight: Displays key fields such as Issuer (CA), Subject, Serial Number, Validity Period, Fingerprint (SHA-1/SHA-256), etc.

Supports Multiple Formats: Capable of recognizing and parsing common certificate file formats like .crt, .pem, .cer.
CSR Parsing: Before applying for a certificate from a CA, parse your Certificate Signing Request (CSR) to verify the accuracy of organization information and domain names.

Path Tracing: Automatically displays the complete trust chain from the root certificate to intermediate certificates, and finally to the site certificate.
Matching Verification: Supports simultaneous upload of certificate and private key, verifying their logical consistency by calculating the Modulus or public key hash.

Localized Processing: For sensitive certificate content or private key matching verification, all logic is executed entirely in the browser frontend. Your private key information is never uploaded to the server, ensuring the absolute security of your server assets.

Field Name	English Identifier	Meaning and Importance
Common Name	Common Name (CN)	The primary domain name bound to the certificate.
Subject Alt Name	Subject Alt Name (SAN)	Other domain names also supported by the certificate (e.g., multi-domain or wildcard).
Validity Period	Not Before / Not After	The certificate's effective and expiration times.
Signature Algorithm	Signature Algorithm	Encryption strength identifier (e.g., sha256WithRSAEncryption).
Fingerprint	Fingerprint	The unique hash identifier of the certificate, used to verify if the certificate has been tampered with.

Mode Selection: Choose "Online Domain Detection" or "Manual Input/File Upload".
Data Submission:
- Mode One: Enter the website URL.
- Mode Two: Paste the certificate text (starting with -----BEGIN CERTIFICATE-----) into the box.
View Results: Click "Start Parsing/Verification", and the system will immediately generate a detailed certificate report.
Troubleshooting: Focus on the red-highlighted warning items (e.g., imminent expiration, outdated algorithm, missing chain).

Ultra-Fast Detection: Global multi-node detection technology, retrieving remote certificates in seconds.
Zero Storage Policy: We do not record any queried certificates or domain names, protecting business confidentiality.
Clean, Watermark-Free: Report results are clear and concise, making screenshots convenient for operations reporting.
Completely Free: No registration required. An essential troubleshooting tool for operations engineers and individual webmasters.

Certificate Validation Tool