AI-first diagnostics
AI Engineer for Your Website
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
124.6K+
Checks Performed
56+
Active Monitors
361+
API Requests
48+
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
Infrastructure
Best VPS Providers 2026: Criteria, Pitfalls and How to Verify
Best VPS providers 2026: Hetzner, DigitalOcean, Vultr, Linode, OVHcloud, Contabo and UpCloud compared by what matters —
Domains
Best Domain Registrars 2026: Where to Buy a Domain and What Matters Beyond Price
Best domain registrars in 2026: where to buy a domain and what matters beyond price — renewal cost vs first-year discoun
Infrastructure
Best Web Hosting Providers 2026: an Engineer's Rating and How to Verify It
Best web hosting providers 2026: eight global picks — Hetzner, DigitalOcean, OVHcloud, SiteGround and more. Transparent
DNS
Best Public DNS Servers 2026: Speed, Privacy and Filtering
The best public DNS servers of 2026 ranked: Cloudflare 1.1.1.1, Google 8.8.8.8, Quad9 9.9.9.9, AdGuard DNS, Yandex.DNS a
Popular guides & reference
Glossary
all →
CDC — Change Data Capture · Definition & Examples
Change Data Capture: stream DB changes in real-time. Debezium, Kafka Connect, WAL, binlog.
Prompt Injection — Attack on LLM
Prompt injection: hijacking an LLM via malicious instructions in input. Direct vs indirect. Defences: guardrails, sanit…
How-to
all →
How to check if a website is blocked in Russia
Diagnose a site blocked in Russia: check the Roskomnadzor EAIS registry, availability from Russian nodes (Moscow, St. P…
Site works for me but not for clients in Russia — what to do
Diagnose a site that works for the owner but is unreachable for clients in Russia. Cause tree: EAIS block, CDN shared-I…
Ports
all →
Port 8883 — MQTT over TLS
TCP port 8883 — MQTT over TLS: encrypted IoT messaging. AWS IoT Core, HiveMQ, Mosquitto TLS.
Port 5900 (TCP) — VNC Remote Desktop
Port 5900 is used by VNC Remote Desktop. Standard port for VNC. Security, how to check, best practices.
Alternatives
all →
DNSDumpster Alternatives 2026 — Fast Subdomain Finder, No Captcha
What to use instead of DNSDumpster: fast CT-log subdomain discovery with no captcha or signup. Honest feature compariso…
Wappalyzer Alternatives 2026 — Free Website Tech Detector, No Extensi…
What to use instead of Wappalyzer: free website technology detection with no extension and no tracking. Honest comparis…
SSL errors
all →
ERR_QUIC_PROTOCOL_ERROR — Chrome HTTP/3 · Browser Error Fix
Chrome ERR_QUIC_PROTOCOL_ERROR — QUIC transport error. Causes: CDN misconfig, middlebox interference, NAT UDP drops.
ERR_QUIC_TIMEOUT — HTTP/3 Connection Timeout · Browser Error Fix
Chrome ERR_QUIC_TIMEOUT — QUIC session timed out. Causes: UDP packet loss, slow network, NAT hairpinning issues.
Research
all →
TLS Cipher Suites 2026 — Top-100k Distribution
Which TLS ciphers are actually used? Cipher negotiation analysis for top-100k: AES-GCM leads, ChaCha20 grows, 3DES gone.
State of SSL/TLS in Runet 2026 — Benchmark
SSL/TLS analysis in Runet: TLS 1.3 adoption, certificates, average grade, top CAs. Based on Enterno.io scans.
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.
200+ HeadersFull set of HTTP response headers
Security HeadersCSP, HSTS, X-Frame-Options and more
Redirects301/302 redirect chains
Custom UASimulate browsers and crawlers
Why teams trust us
150+
headers analysed
HSTS
security check
<2s
response time
Free
no signup needed
How it works
1
Enter URL
2
Get all headers
3
Check security
What are HTTP Headers?
HTTP headers are metadata exchanged between browser and server on every request. They control caching, security, compression, and redirect behavior.
Full Analysis
All response headers categorized: security, cache, content.
Fast Results
Results in seconds from any device without registration.
Redirect Tracing
Visualize redirect chains — each hop with status code and URL.
Check History
Save and compare results — track header changes over time.
Who uses this
DevOps
server header check
Security
CSP, HSTS, X-Frame audit
Developers
cache header debugging
SEO
redirect chain check
Common Mistakes
Missing HSTSWithout HSTS the browser may make the first request over HTTP. Add
Strict-Transport-Security.No Content-Security-PolicyCSP prevents XSS attacks. Even a basic CSP is better than none.
Missing X-Frame-OptionsWithout it, your site can be embedded in an attacker's frame (clickjacking).
Server exposes version
Server: Apache/2.4.51 helps attackers find vulnerabilities. Hide the version.Best Practices
Enable HSTS with preloadThe
preload directive adds the domain to the browser's built-in HSTS list.Configure Cache-ControlUse
immutable for static assets and no-store for sensitive pages.Check after each deployServer updates can reset security headers. Check after every deploy.
Use monitoringSet up an HTTP monitor to get notified when status or headers change.
Get more with a free account
HTTP header check history, API keys and uptime monitoring.
Sign up free