Stay secure, stay informed

Cert-Checker is a privacy-focused Go tool that monitors SSL/TLS certificates on domains and local files, analyzes expiration dates, and alerts users if any issues are detected. It offers both a powerful command-line interface for automation and an interactive web dashboard.

Latest Release

May 30, 2026 Version 1.4.0

Features

• Certificate Verification

  • Hybrid Scanning: Supports remote domains (https://example.com) and local certificate files (.pem, .crt, .key).
  • Chain Validation: Verifies certificate chains, detects self-signed certificates, and identifies missing intermediates.
  • CI/CD Ready: Returns specific exit codes (0=OK, 1=Warning, 2=Error) for integration into pipelines.

• Interactive Web Dashboard

  • Real-Time Visualization: Responsive UI with Dark Mode support.
  • Filtering: Filter by status, search by domain/issuer, and sort by expiration date.
  • Auto-Refresh: Configurable background updates (e.g., every 15 mins) to keep data fresh.

• Security & Privacy

  • Local Storage: No external databases or cloud dependencies required.
  • HTTPS Dashboard: Built-in support for self-signed or Let's Encrypt certificates to secure the dashboard connection.

• Automation & Management

  • Cron Job Manager: Built-in interactive CLI to create, list, and remove scheduled scans.
  • Reporting: Exports detailed JSON reports with timestamps for archival or external processing.
  • Save Certificates: Download valid certificates (optional)

Quick Start

Build from source

git clone https://github.com/mrtoadie/go-check-cert.git
cd go-check-cert
go build -o cert-checker

Run directly (without build)

go run .

Arch Linux

Install from AUR

yay -S cert-checker

Launch with Dashboard

# Without HTTPS
./cert-checker -web

# With HTTPS and self-signed certificate
./cert-checker -web -cert ./certs/cert.pem -key ./certs/key.pem

Open http://localhost:8080 or https://localhost:8080 in your browser.

Screenshots

Command Line Options

Flag	Alias	Description
-a	-advanced	Show advanced certificate details
-f	-file	Path to a local .pem, .crt, .cer, or .key file
-c	-cron	Interactive Cron setup
-dl	-download	Download valid certificates to certs folder
-md	-markdown	Saves results in Markdown format
-ls	-list	List and manage Cron jobs
-l	-log	Show cron job log file
-ci	-ci-mode	CI/CD Mode (non-interactive, uses urls.txt)
-w	-web	Start web dashboard on localhost:8080
-cert		Path to SSL certificate file (.pem/.crt)
-key		Path to SSL private key file (.pem)
-h	-help	Display help message

Examples

Check a single certificate:

./cert-checker -f ./server.crt

Set up cron job(s):

./cert-checker -c

List active Cron jobs:

./cert-checker -ls

Configuration

The tool automatically creates a configuration file on the first run.

Location: ~/.config/cert-checker/urls.txt

Format: One URL per line. Comments starting with # are supported.

Output Examples

Text Output (Default)

=== RESULTS ===

1. forum.linuxguides.de
   Days:  44 | Valid: 26.02.26 → 27.05.26
   Issuer: R12
------------------------------------
2. github.com
   Days:  52 | Valid: 06.03.26 → 03.06.26
   Issuer: Sectigo Public Server Authentication CA DV E36
------------------------------------
=== SUMMARY ===
OK: 0 | Warn: 2 | Exp: 0 | Err: 0

JSON Output

{
  "generated_at": "2026-05-03T14:47:42Z",
  "total_count": 1,
  "results": [
    {
      "url": "https://github.com",
      "status": "OK",
      "days_remaining": 180,
      "is_chain_complete": true,
      "key_algorithm": "RSA",
      "key_size": 2048
    }
  ]
}

Cron Job Management

Interactive Menu

./cert-checker -cron

Options:

1. Set up cron job – Create a new automated check
2. List & manage jobs – View/delete existing jobs
3. Exit – Quit the program

List Cron Jobs

./cert-checker -list
``

Output:
```bash
=== CERTIFICATE CHECK CRON JOBS ===

1. # cert-checker - 2026-05-03 14:47:42
   0 8 * * * /home/user/cert-checker -ci >> /tmp/cert-check.log 2>&1

2. # cert-checker - 2026-05-03 15:00:00
   0 */6 * * * /home/user/cert-checker -ci >> /tmp/cert-check.log 2>&1

Total: 2 job(s) found.

Delete Individual Jobs

• Run ./cert-checker -list
• Select "Delete individual jobs"
• Mark jobs with Spacebar
• Confirm with Enter

Usage

The input is interactive and automatically detects the correct format.

• Press Enter to use the default list of URLs (~/.config/cert-checker/urls.txt)

• To check individual URLs: github.com or github.com, ubuntu.com, example.org

• Check local certificate file: '~/github.pem'

• Certificate files can also be checked using a flag: cert-checker --file ~/github.pem

Certificate files with the following extensions work: .pem, .cer, .crt, .key

Tested on

✅ Arch Linux

✅ Solus

✅ WSL2 (Ubuntu)

License

go-check-cert is licensed under the MIT License.