Skill 4

Lightweight website uptime monitor. Check if URLs are up, measure response times, detect content changes via hashing, and verify expected content. Zero dependencies.

Website Monitor

A zero-dependency Python tool for checking website availability, measuring response times, and detecting content changes. Uses only Python's standard library (urllib) — no requests, no aiohttp, no external packages.

Features

• Uptime checking: Verify any URL returns the expected HTTP status code
• Response time measurement: Precise millisecond timing for each request
• Content change detection: SHA-256 based hashing to detect when page content changes between checks
• Text verification: Confirm that specific text appears in the response body
• Multi-URL support: Check multiple sites in a single command
• JSON output: Machine-readable output for integration with other tools and dashboards
• Exit codes: Returns exit code 1 if any site is down, making it perfect for shell scripts and cron jobs

Usage Examples

Simple uptime check:

bash

python main.py https://example.com
# ✅ https://example.com
#    Status: 200
#    Response: 142ms
#    Size: 1256 bytes
#    Hash: fb91d75a6bb43078

Check multiple sites at once:

bash

python main.py example.com google.com github.com

Detect content changes (compare against a previous hash):

bash

python main.py https://example.com --hash-check fb91d75a6bb43078
# Shows "Changed: YES ⚠️" or "Changed: No"

Verify a page contains expected text:

bash

python main.py https://status.example.com --contains "All Systems Operational"

Expect a specific status code (e.g., redirect):

bash

python main.py https://old.example.com --expect 301

JSON output for scripting:

bash

python main.py example.com github.com --json | jq '.[] | select(.up == false)'

Use in a cron job or script:

bash

python main.py https://mysite.com || echo "ALERT: Site is down!" | mail -s "Downtime Alert" [e-mail]

Command Line Options

• urls — One or more URLs to check (auto-prepends https:// if missing)
• --timeout N — Request timeout in seconds (default: 10)
• --expect N — Expected HTTP status code (default: 200)
• --contains TEXT — Verify response body contains this string
• --hash-check HASH — Previous content hash to compare against for change detection
• --json — Output results as JSON array

Exit Codes

• 0 — All sites are up and match expectations
• 1 — One or more sites are down or failed checks