HTTP Checker — Advanced Mode
The Enterno.io AI engineer checks your site — HTTP headers, SSL, DNS, speed — finds problems and writes a clear fix spec. 10 free monitors, no card required.
AI finds the problem — and writes the fix spec
Example report: the scan on the left, a ready-to-hand developer spec on the right.
Scanning example.com
67%
- HTTPS✓
- Content-Security-Policy✗
- Caching!
- DNS & MX✓
- Speed (LCP, TTFB)
32 of 48 checks done…
Problem found
Missing Content Security Policy (CSP)
The site does not send a Content-Security-Policy header. This raises the risk of XSS attacks and injections.
Ready spec for the developer
add_header Content-Security-Policy "
default-src 'self';
script-src 'self';
style-src 'self';
object-src 'none';
base-uri 'self';
frame-ancestors 'none';
" always;The spec is generated by AI from the detected problem and security best practices. Illustrative example.
How It Works
Three simple steps to a full analysis
01
Check
68+ tools scan your site in seconds
02
AI diagnosis
AI finds problems and explains the causes
03
Ready spec
Copy the instructions and hand them to a developer
All Tools
Comprehensive analysis and monitoring for your website
Website Analysis
12Domain & DNS
10Network
8Security & Email
11Why enterno.io
1.2M+
Checks Performed
671+
Active Monitors
24.5K+
API Requests
68+
Free Tools
01
Free
All basic tools available without registration or limits
02
Fast
Results in seconds. Servers in Russia — minimal latency
03
API Access
REST API to automate checks and integrate into your projects
04
24/7 Monitoring
Telegram and email alerts for site outages or SSL expiration
05
Telegram alerts
Instant notifications on outages, SSL expiry and DNS problems
06
Status pages
Public status pages for your services and clients
Articles & Guides
Useful resources on web development and administration
Latest articles
HTTP
PHP-FPM and 502: queue, pm.max_children and pool sizing
See how a saturated PHP-FPM pool can contribute to 502 or 504. Inspect logs and the listen queue, then estimate pm.max_c
HTTP
nginx upstream timed out (110): which timeout to inspect
Diagnose nginx upstream timed out (110) by phase: connect, send or read. Correlate error logs, upstream timing and confi
SSL/TLS
Nginx TLS configuration: an annotated path toward A+
Annotated nginx TLS configuration covering protocols, certificate chains, HSTS and validation. An A+ grade depends on a
SSL/TLS
Let’s Encrypt ended OCSP: what to check on your server
Let’s Encrypt shut down OCSP on August 6, 2025. Check stapling, certificate metadata and nginx settings without mistakin
Popular guides & reference
Glossary
all →
Rust Web Frameworks 2026: Axum vs Actix Web vs Rocket
Axum, Actix Web, Rocket and Warp compared: Tokio async runtime, latency, middleware and ergonomics of each Rust web fra…
Cloudflare R2: S3-Compatible Storage, Pricing, No Egress
Cloudflare R2 is S3-compatible object storage with zero egress fees, $0.015 per GB-month, working with aws-cli, rclone …
How-to
all →
How to Set Up a DMARC Record — 2026 Guide
Step-by-step DMARC setup: p=none→quarantine→reject, rua/ruf aggregate reports, SPF+DKIM alignment. Avoid the spam folde…
How to Configure CORS — 2026 Guide
Step-by-step CORS setup: Access-Control-Allow-Origin, preflight, credentials, wildcard vs specific. nginx/Apache/Expres…
Ports
all →
Port 995: POP3S, Secure POP3 Email over TLS (vs Port 110)
995 is POP3S: POP3 inside TLS from the first byte, the secure version of port 110. If you run no POP3 mail service, kee…
Port 5060: SIP for VoIP Calls (5061 Is SIP over TLS)
5060 is the default SIP port for VoIP over UDP and TCP; SIP over TLS uses 5061. If exposed, it draws SIP flood attacks.
Alternatives
all →
New Relic Synthetics Alternative: No Per-Check Billing
New Relic Synthetics per-check billing vs flat plans: check a URL from 3 regions here, then monitor it without a meter …
UptimeRobot Alternative: Free Plan, Telegram, Moscow Checks
UptimeRobot and a free monitor with SSL, DNS and cron checks: test a URL from 3 regions here. UptimeRobot gives more fr…
SSL errors
all →
upstream connect error or disconnect/reset before headers: Fix
Envoy and Istio usually return it as 503. The reset reason names the cause: connection timeout, overflow, connection fa…
Trust Anchor for Certification Path Not Found: Android Fix
Android apps and WebView do not trust the server's CA: a self-signed or private CA, a missing intermediate, or an old A…
Research
all →
Nginx Market Share 2026: Why Surveys Say 14% to 44%
nginx holds 14.45% to 43.92% in Netcraft's July 2026 survey and 31.3% at W3Techs. Why the numbers differ, and 85.9% of …
HTTP/3 in 2026: 30.4% of requests, 40.3% of sites, 7.1% in .ru
HTTP/3 is 30.4% of human requests and 40.3% of sites; the difference is explicable. Our 600-host measurement: 7.1% of .…
Simple, transparent pricing
Start free. Upgrade when you need more control.
What our users say
Switched from UptimeRobot to Enterno — faster monitoring, better UI, and everything in Russian. Now tracking 30+ client sites.
Simple, clear API. Integrated checks into CI/CD in an hour — now every deploy automatically verifies SSL and security headers.
Perfect tool for freelancers. Free plan covers my needs, and I send PDF reports to clients as-is.
SSL Encrypted
Hosted in Russia
GDPR / 152-FZ Compliant
99.5% target availability
HTTP Headers Analysis Tool
Check HTTP response headers, status codes, redirect chains, server timing, and security headers for any website. Our tool sends a real request from a server in Russia and shows the complete response including all headers, cookies, and performance metrics. Use it to debug caching, security configuration, CORS, and content delivery.
Frequently Asked Questions
What are HTTP headers?
HTTP headers are metadata sent between a browser and a server with every request and response. They control caching, security, content type, redirects, and many other aspects of how a web page is delivered.
How to check HTTP headers of a website?
Enter any URL in the form above and click Check. The tool will show all response headers, status codes, redirects, cookies, and a security header analysis.
What security headers should every site have?
Key security headers include Content-Security-Policy, Strict-Transport-Security (HSTS), X-Content-Type-Options, X-Frame-Options, and Permissions-Policy. They protect against XSS, clickjacking, and other common attacks.
What does the status code mean in HTTP response?
HTTP status codes indicate the result of a request: 2xx means success, 3xx means redirection, 4xx means client error (e.g., 404 Not Found), and 5xx means server error. The exact code helps diagnose issues.
Is this tool free?
Yes, the HTTP header checker is completely free with no limits on the number of checks. You can also create a free account to save your check history and access additional features.
What is HSTS and why is it important?
HSTS (HTTP Strict Transport Security) is a header that tells the browser to always use HTTPS for a given site. It prevents protocol downgrade attacks and traffic interception through insecure HTTP connections.
How to check redirect chains?
Our tool automatically follows all redirects (301, 302, 307, 308) and shows the complete redirect chain. Long chains slow down page loading and weaken SEO — it is recommended to have no more than 1-2 redirects.
How to set up 24/7 website uptime monitoring?
Sign up free, add a URL on <a href="/en/monitors">/en/monitors</a>, pick an interval (5 min on the free plan, down to 1 min from Navigator) and alert channels (email, Telegram, webhook). The free Scout plan includes 10 monitors forever, no card. On Scout, Explorer and Pioneer checks run from a single location (Moscow); from Navigator up, monitors are checked from multiple locations (12).
What are Core Web Vitals and how to improve them?
Core Web Vitals — 3 Google speed metrics: LCP (main content paint, < 2.5 s — good), CLS (layout shift, < 0.1), INP (click responsiveness, < 200 ms). They affect ranking. Test your site via <a href="/en/speed">/en/speed</a> — the tool returns a 0-100 score and concrete opportunities: lazy-loading, image compression, CSS/JS minification.
Where do alerts go, and which integrations are available?
Monitor down and recovery alerts go to email, Telegram (via our @enterno_io_bot), Slack, Google Chat, PagerDuty, Jira and Splunk On-Call on every plan, including the free one: connect these channels in the Integrations section. Discord and Microsoft Teams get alerts at the webhook URL set on the monitor. HMAC-signed webhooks are on every plan too — use them to connect Zapier, Make, n8n or your own systems. Slack also receives domain expiry, new subdomain and security re-check notifications. Opsgenie and Mattermost are not connected directly — only through a webhook and Zapier, Make or n8n.