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
48+ 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
81.4K+
Checks Performed
106+
Active Monitors
472+
API Requests
61+
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
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SSL/TLS
HTTPS Not Working: Causes, Checks and How to Fix It
HTTPS not working: tell a local fault from a server one, decode NET::ERR_CERT_* errors, and check the certificate, chain
SEO
What Is Website Indexing: How It Works and How to Check
What website indexing is in plain terms: how crawling differs from indexing, how a page gets into the index, how to chec
DNS
What Is DNS: How It Works and Why You Need It, Explained
What is DNS and how it works: the full path of a lookup, resolver roles, caching and TTL, private DNS over TLS and HTTPS
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Core Web Vitals — LCP, INP, CLS in 2026
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robots.txt — What It Is and How It Works
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How to Set Up Prometheus + Grafana — 2026
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Step-by-step SSH hardening: keys instead of password, fail2ban, port change, AllowUsers. Step-by-step guide.
Ports
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Port 9100 (TCP) — Prometheus node_exporter
Port 9100 is used by Prometheus node_exporter. Standard port for node_exporter. Security, how to check, best practices.
Port 10250 (TCP) — Kubernetes kubelet API
Port 10250 is used by Kubernetes kubelet API. Standard port for kubelet. Security, how to check, best practices.
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Hoppscotch Alternatives 2026 — Web API Clients
Hoppscotch — open-source web-based API client. Alternatives: Enterno.io, Postman, Insomnia, Bruno.
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SSL errors
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ERR_BLOCKED_BY_RESPONSE: X-Frame-Options, CSP and CORP — Fix
an iframe refused by X-Frame-Options or CSP frame-ancestors is the usual cause; CORP and COEP are rarer. How to tell wh…
ERR_HPACK_DECODING_FAILED — HTTP/2 Header · Browser Error Fix
Chrome ERR_HPACK_DECODING_FAILED — HTTP/2 HPACK decompression error. Malformed headers, encoder state corruption.
Research
all →
Web Accessibility in Runet 2026 — WCAG Audit
Accessibility research across 500 Russian sites: 73% fail WCAG 2.2 AA. Common mistakes and SEO impact.
Core Web Vitals in Runet 2026 — Top-500 Benchmark
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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
99.9% Uptime SLA
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 (1-5 min) and alert channels (Email, Telegram, Slack, webhook). The free Scout plan includes 10 monitors forever, no card. Checks run from Russia (MSK), Europe (DE), and US (East) on the Pro plan.
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.
Are there Telegram, Slack and PagerDuty integrations?
Yes. All major channels integrate in one click: Email, Telegram (via our @enterno_io_bot), Slack (webhook), Discord (webhook), PagerDuty (Events API v2), Jira (auto-create issues), webhooks with HMAC signing. Plus SMS and Opsgenie on the Business plan. Configure in Settings → Notifications.