A simple HTTP URL testing service built with Go. Quickly debug why URLs fail - check if you're blocked, rate-limited, or hitting other issues.
With so many AI crawlers out there, websites often block requests. This tool helps you:
- Detect if your IP is blocked (403/429 responses)
- Check if redirects are causing issues
- See exact HTTP status and headers
- Measure response times
- Verify SSL/TLS errors
- Debug why your requests fail
- Check HTTP status code and response time
- View response headers and body preview
- Track redirects
- Detect blocked requests (403/429)
- See SSL/TLS errors
- Web UI included
- Go 1.21+
go mod download go run main.goVisit http://localhost:8080
curl -X POST http://localhost:8080/api/test \ -H "Content-Type: application/json" \ -d '{"url": "https://example.com"}'make build # Compile make run # Run locally make test# Run tests make test-coverage # Show coverage make docker-build # Build Docker image make docker-run # Run Docker locally# Pull the latest image docker pull sammylin/url_checker:latest # Run the container docker run -p 8080:8080 sammylin/url_checker:latestdocker build -t url-checker . docker run -p 8080:8080 url-checkerdocker run -p 9000:8080 -e PORT=8080 sammylin/url_checker:latestRequest:
{"url": "https://example.com" }Response (Success):
{"success": true, "statusCode": 200, "responseTime": 234, "finalUrl": "https://example.com/", "headers":{"Content-Type": "text/html", "Server": "nginx" }, "bodyPreview": "<!DOCTYPE html>...", "truncated": false, "blocked": false, "userIP": "1.2.3.4", "serverIP": "5.6.7.8" }Response (Error):
{"success": false, "error": "DNS error: host not found", "blocked": false, "userIP": "1.2.3.4", "serverIP": "5.6.7.8" }Returns OK
PORT- Server port (default: 8080)
curl -X POST http://localhost:8080/api/test \ -H "Content-Type: application/json" \ -d '{"url": "https://example.com"}'Look for:
"statusCode": 403- Access forbidden"statusCode": 429- Rate limited"blocked": true- Detected as blocked
If a URL redirects, you'll see:
{"finalUrl": "https://example.com/redirected", "statusCode": 200 }Some sites redirect blocked requests to a login page. Check the finalUrl to see where you ended up.
If there's an SSL error:
{"error": "x509: certificate signed by unknown authority" }This means the certificate chain is broken or self-signed.
Headers tell you a lot:
Server: cloudflare- Behind Cloudflare (may have stricter rules)X-Frame-Options: DENY- Can't iframe thisRetry-After: 3600- Rate limited, retry in 1 hour
403 Forbidden
- Your IP is blocked
- User-Agent is blocked
- Missing required headers
429 Too Many Requests
- Rate limited
- Too many requests from your IP
- Need to add delays between requests
Connection Timeout
- Server is down
- Firewall blocking
- Network issue
SSL Certificate Error
- Self-signed certificate
- Expired certificate
- Wrong domain
# Run tests go test ./... # Format code gofmt -w main.go # Check coverage go test -cover ./...MIT