Idiomas

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.

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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.

   
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Sobre a ferramenta
Grátis, sem cadastro. See o cabeçalhos browsers e rastreadores receive: cada redirecionamento salto, separate security e SEO grades, edge fingerprints, compression, e um honesto HTTP/3 signal.
Inspecionar cada HTTP resposta cabeçalho em um redirecionamento cadeia, com security e SEO grades, CDN fingerprints, compression facts, um raw curl-style view, e um optional environment diff.
Recursos
  • Features Concluído cabeçalhos para cada observado redirecionamento salto. Separate determinístico security e HTTP-level SEO grades. Navegador, Googlebot, e compatível rastreador user-agent choices. Compression, edge fingerprint, e honesto HTTP/3 advertisement facts. Optional final-response environment diff e raw cabeçalho exportar view. Session-local common-header frequency para up para cinco URLs.
  • Como funciona Um limitado no servidor verificador sends o selecionado user-agent, registros cada redirecionamento resposta sem hiding intermediário cabeçalhos, e retorna normalized cabeçalho maps e timings. Browser-side functions grade o final resposta, análise Link cabeçalhos, inspecionar compression e protocolo advertisements, identify um pequeno set de edge fingerprints, produzir um curl-style view, e diff um optional second final resposta. O pequeno batch mode counts campos somente across o final respostas buscado em que run e labels names de um local status-preserving instantâneo de o IANA HTTP Campo Nome Registry.
  • O que o resultados mean Security grade deducts 20 points por failure e 8 por aviso across o implemented cabeçalho rules. SEO grade avalia X-Robots-Tag, Link canonical e hreflang, Vary, cache directives, e ETag. Pass confirms um rule; info é contexto sem um pontuação penalty. Delivery fingerprint é evidência sobre um público edge, não prova de o origin host. Comparação lists changed final-response cabeçalho values, não HTML ou comportamento differences.
  • Cache diagnostics
Como funciona
Enter um público URL e escolha o navegador, search-crawler, ou AI-crawler user-agent você want para send. Optionally adicione um staging ou comparação URL; somente final-response cabeçalhos são diffed. Escolha Verificação cabeçalhos , start com o dois grades, então inspecionar o exato constatação e cabeçalho evidência. Revisão cada redirecionamento resposta e usar o raw curl-style view quando você precisa para copy o Concluído observado mapa.
Limitações
  • O relatório cannot expose negotiated HTTP version, TLS certificate detalhes, privado origin infrastructure, ou cabeçalhos adicionado somente inside um user's rede. O Buscar Cabeçalhos API pode combine repeated campo lines: parsed combined values são assessed, but o original field-line order e boundaries cannot ser reconstructed. User-agent strings originate de um Cloudflare datacenter, não verificado rastreador IP intervalos. Isso faz não inspecionar HTML metadados, application security, ou whether um 200 body é correto.
  • Não. O grade covers um defined set de público resposta cabeçalhos. Isso faz não test application vulnerabilities, autenticação, servidor configuração, dependency risk, ou whether um policy funciona correctly para o application.
Perguntas frequentes
Faz o ferramenta preservar repeated cabeçalho campo lines?
Não exactly. O Worker Buscar Cabeçalhos API exposes um normalized, potentially combined value. O verificador parses e assesses que combined value, but isso cannot reconstruct o original order ou boundaries de repeated campo lines.
São URLs saved?
Não. O URL é buscado para build este relatório e um short-lived edge cache pode reuse o mesmo URL e user-agent resposta para sobre ten minutos.
Por que faça navegador e Googlebot resultados differ?
Sites pode vary cabeçalhos por user-agent. Este sends o selecionado user-agent string de um Cloudflare datacenter, não de um verificado rastreador IP intervalo.
Faz o SEO grade inspecionar HTML canonical e robots tags?
Não. Isso avalia HTTP-level signals such como X-Robots-Tag e Link cabeçalhos. Page-level canonical e robots elements exigir um HTML-aware verificador.
Faz este mostrar o HTTP version?
Workers faça não expose o negotiated HTTP version. O ferramenta somente relatórios quando Alt-Svc advertises HTTP/3; que é não prova este solicitação usado HTTP/3.