Bahasa

HTTP Header Checker

Free, no signup. See the headers browsers and crawlers receive: every redirect hop, separate security and SEO grades, edge fingerprints, compression, and an honest HTTP/3 signal.

Built by Patrick Stox

Request user-agent

A matching user-agent does not make this request originate from that crawler’s verified IP range.

This makes two user-triggered requests for one URL from Cloudflare infrastructure. It compares user-agent responses, not verified crawler behavior or crawler IP access.

Compare staging or another URL

The report compares the final response headers from two independent checks.

Checks run from our server; we fetch the URL you enter and don't keep the results. Complete response header maps are returned to your browser. Repeating the same URL and user-agent within about ten minutes may reuse a short-lived edge cache. Anonymous run-level outcome counters may be used for aggregate research; URLs, domains, IPs, and identifiers are never included, and no statistic is released below 100 runs.

Feedback
Report a bug

Found something broken in Http Header Checker? Let us know what happened — this goes straight to a private triage queue, not a public list.

What will be sent 
 No tool inputs, uploads, pasted source, complete results, query parameters, or URL fragments are attached automatically. You can edit or remove the selected passage above. Browser and anti-abuse metadata is processed for spam prevention. 
  
 
  
 
 
  
 
 
   
 
 Compare common headers across up to five URLs    
Frequency is calculated in this browser from the live final responses in this run. It is not a global popularity dataset.
   
 
 
Sample report
Illustrative example — exact grading for the fixed header map below
HTTP/2 200
strict-transport-security: max-age=31536000
cache-control: public, max-age=3600
etag: "abc123"
Security headers
F40/100
HSTS passes. Missing CSP fails; missing framing protection, Referrer-Policy, nosniff, Permissions-Policy, and COOP are warnings. Missing COEP is informational.
SEO headers
A+100/100
Cache-Control and ETag pass. Missing X-Robots-Tag, Link canonical, and Vary are informational in this HTTP-only grade.
The displayed HTTP/2 line is illustrative input only: the live Worker cannot expose the negotiated HTTP version.
 
 
 
How to use it
 
  1. Enter a public URL and choose the browser, search-crawler, or AI-crawler user-agent you want to send.
  2. Optionally add a staging or comparison URL; only final-response headers are diffed.
  3. Choose Check headers, start with the two grades, then inspect the exact finding and header evidence.
  4. Review every redirect response and use the raw curl-style view when you need to copy the complete observed map.
 
 
 
       
     
     
 
What the results mean
  • Security grade deducts 20 points per failure and 8 per warning across the implemented header rules.
  • SEO grade evaluates X-Robots-Tag, Link canonical and hreflang, Vary, cache directives, and ETag.
  • Pass confirms one rule; info is context without a score penalty.
  • Delivery fingerprint is evidence about a public edge, not proof of the origin host.
  • Comparison lists changed final-response header values, not HTML or behavior differences.
 
How it works
A bounded server-side checker sends the selected user-agent, records each redirect response without hiding intermediate headers, and returns normalized header maps and timings. Browser-side functions grade the final response, parse Link headers, inspect compression and protocol advertisements, identify a small set of edge fingerprints, produce a curl-style view, and diff an optional second final response. The small batch mode counts fields only across the final responses fetched in that run and labels names from a local status-preserving snapshot of the IANA HTTP Field Name Registry.
 
Features
  • Complete headers for every observed redirect hop.
  • Separate deterministic security and HTTP-level SEO grades.
  • Browser, Googlebot, and supported crawler user-agent choices.
  • Compression, edge fingerprint, and honest HTTP/3 advertisement facts.
  • Optional final-response environment diff and raw header export view.
  • Session-local common-header frequency for up to five URLs.
 
Limitations
 
The report cannot expose negotiated HTTP version, TLS certificate details, private origin infrastructure, or headers added only inside a user's network. The Fetch Headers API may combine repeated field lines: parsed combined values are assessed, but the original field-line order and boundaries cannot be reconstructed. User-agent strings originate from a Cloudflare datacenter, not verified crawler IP ranges. It does not inspect HTML metadata, application security, or whether a 200 body is correct.
 
Frequently asked questions
 
Does the tool preserve repeated header field lines?
Not exactly. The Worker Fetch Headers API exposes a normalized, potentially combined value. The checker parses and assesses that combined value, but it cannot reconstruct the original order or boundaries of repeated field lines.
Does this show the HTTP version?
Workers do not expose the negotiated HTTP version. The tool only reports when Alt-Svc advertises HTTP/3; that is not proof this request used HTTP/3.
Why do browser and Googlebot results differ?
Sites can vary headers by user-agent. This sends the selected user-agent string from a Cloudflare datacenter, not from a verified crawler IP range.
Are URLs saved?
No. The URL is fetched to build this report and a short-lived edge cache may reuse the same URL and user-agent response for about ten minutes.
Is a high security-header grade proof that a site is secure?
No. The grade covers a defined set of public response headers. It does not test application vulnerabilities, authentication, server configuration, dependency risk, or whether a policy works correctly for the application.
Does the SEO grade inspect HTML canonical and robots tags?
No. It evaluates HTTP-level signals such as X-Robots-Tag and Link headers. Page-level canonical and robots elements require an HTML-aware checker.
 
Next stepHosting Checker — look up the exact spec and expected values.

People also explore
ToolDNS CheckerToolWebsite Down CheckerToolDomain ReportArticleMixed ContentArticleCaching for SEOArticleWebsite Hosting Migration SEO
 
 
 
Feature requests for Http Header Checker
 

Upvote what you want most. New ideas can be submitted from the floating Feedback menu;
      requests appear here once approved, and the most-wanted rise to the top.

   
Loading…
  
  ➕ Request a feature   
New requests are reviewed before they appear here.
 
     
  
  
 
 
 
 
    
 
 
   
Tentang alat
Tidak. grade covers ditentukan atur dari publik header respons. Ini tidak uji aplikasi vulnerabilities, authentication, server konfigurasi, dependency risiko, atau apakah kebijakan berfungsi correctly untuk aplikasi.
Fitur Lengkap header untuk setiap teramati pengalihan lompatan. Terpisah deterministik keamanan dan HTTP-tingkat SEO grades. Browser, Googlebot, dan supported perayap pengguna-agen pilihan. Compression, edge fingerprint, dan honest HTTP/3 advertisement fakta. Opsional akhir-respons environment diff dan mentah header ekspor lihat. Sesi-lokal umum-header frequency untuk up untuk five URLs.
Adalah tinggi keamanan-header grade proof yang situs adalah secure?
Fitur
  • URL untuk periksa
  • Arti hasil Keamanan grade deducts 20 menunjuk per kegagalan dan 8 per peringatan di seluruh diterapkan header aturan. SEO grade evaluates X-Robots-Tag, Tautan canonical dan hreflang, Vary, cache direktif, dan ETag. Lulus confirms satu aturan; info adalah konteks tanpa score penalty. Pengiriman fingerprint adalah bukti tentang publik edge, tidak proof dari asal host. Comparison daftar berubah akhir-respons header nilai, tidak HTML atau perilaku differences.
  • laporan tidak dapat mengekspos negotiated HTTP versi, TLS certificate details, privat asal infrastructure, atau header added hanya inside pengguna's jaringan. Ambil Header API mungkin combine repeated field baris: parsed gabungan nilai adalah assessed, tetapi original field-baris urutan dan boundaries tidak dapat menjadi reconstructed. Pengguna-agen strings originate dari Cloudflare datacenter, tidak terverifikasi perayap IP ranges. Ini tidak periksa HTML metadata, aplikasi keamanan, atau apakah 200 isi adalah benar.
  • Bandingkan browser respons dengan dipilih perayap pengguna-agen
  • Bagaimana ini berfungsi dibatasi sisi server pemeriksa mengirim dipilih pengguna-agen, catatan setiap pengalihan respons tanpa menyembunyikan menengah header, dan mengembalikan ternormalisasi header maps dan timings. Browser-side functions grade akhir respons, uraikan Tautan header, periksa compression dan protokol advertisements, identifikasi small atur dari edge fingerprints, produce curl-style lihat, dan diff opsional second akhir respons. small batch mode counts fields hanya di seluruh akhir respons diambil di yang jalankan dan memberi label menyebut dari lokal status-mempertahankan snapshot dari IANA HTTP Field Nama Registry.
Cara kerja
Adalah URLs tersimpan? Mengapa browser dan Googlebot hasil berbeda? Re-periksa sekarang Workers tidak mengekspos negotiated HTTP versi. alat hanya laporan ketika Alt-Svc advertises HTTP/3; yang tidak proof ini permintaan digunakan HTTP/3.
Batasan
  • Ini membuat dua pengguna-triggered permintaan untuk satu URL dari Cloudflare infrastructure. Ini membandingkan pengguna-agen respons, tidak terverifikasi perayap perilaku atau perayap IP akses.
  • Bandingkan staging atau lain URL
  • Unduh grade card
  • Melakukan alat pertahankan repeated header field baris?
Pertanyaan umum
laporan membandingkan akhir header respons dari dua independent memeriksa.
Situs dapat vary header oleh pengguna-agen. Ini mengirim dipilih pengguna-agen string dari Cloudflare datacenter, tidak dari terverifikasi perayap IP range.
Tidak. URL diambil untuk menyusun laporan ini dan short-lived edge cache mungkin reuse sama URL dan pengguna-agen respons untuk tentang ten minutes.
Melakukan ini tunjukkan HTTP versi?
Periksa setiap HTTP respons header di pengalihan rantai, dengan keamanan dan SEO grades, CDN fingerprints, compression fakta, mentah curl-style lihat, dan opsional environment diff.
Pengiriman & transfer fakta
Tidak exactly. Worker Ambil Header API exposes ternormalisasi, potentially gabungan nilai. pemeriksa parses dan assesses yang gabungan nilai, tetapi ini tidak dapat reconstruct original urutan atau boundaries dari repeated field baris.
Periksa header