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codeforces.com No paid content found

Categories: Development Social & Community

Tags: programming algorithm contest competition informatics olympiads c++ java graphs vkcup

Codeforces. Programming competitions and contests, programming community

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Updated: 2026-09-01 08:24 Language: English (default) Access: Normal

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Codeforces Full homepage screenshot

Website Overview

An established domain and managed infrastructure suggest continuity of operations and may support dependable delivery, although neither guarantees service quality. Several search or sharing settings need attention. Together they may make snippets, preview images or preferred URLs less consistent across platforms.

Domain and Registration

Registered in 2009, this domain has about 17 years of history. That suggests continuity, although ownership and purpose may have changed. Transfer-protection status is present, helping reduce the risk of unauthorized domain transfers. The registrar is Gandi SAS, a widely used domain service provider. The domain uses the common .com extension, which is not an independent safety signal.

DNS and Email

Nameservers are provided by Cloudflare, indicating managed DNS hosting. MX records point to the Yandex Mail email service. No CNAME was found; the observed records resolve directly to addresses. SPF and DMARC are configured. DKIM status is unknown. TXT records include verification markers for Google. Such markers may also remain after a service stops being used.

TLS and Certificates

The public key uses EC with 256 bits. The server supplied a complete certificate chain. No organization name is present in the certificate; the available fields are consistent with domain validation. The certificate was issued within the Google Trust Services cloud or CDN ecosystem. The certificate's total validity is about 90 days, consistent with a short renewal cycle.

HTTP and Browser Security

The response lacks these common security headers: CSP, Referrer-Policy, Permissions-Policy. No X-Powered-By header was found, reducing one common source of backend fingerprinting information. The cf-ray response header indicates a CDN or caching proxy in the delivery path. No obvious internal addresses or debug information were found in the headers. The Server header identifies cloudflare without an exact version.

Technology Stack Analysis

The public page identifies Google Analytics, Cloudflare without precise versions, leaving fewer clues for version-specific scanning.

Search and Social Sharing

No homepage canonical URL was detected. If duplicate URLs exist, consolidation may be less explicit. Open Graph is partially configured; og:description, og:type is missing. The title has 10 characters, within a common display range. A meta description is present, with 72 characters. No Generator meta tag is publicly exposed.

Hosting and Email

DNSCloudflare
HostingCloudflare
EmailYandex Mail
Location Location unknown 104.26.6.164

Pages, Search and Sharing

Meta descriptionCodeforces. Programming competitions and contests, programming community
Canonical URLNot detected
LanguageEnglish (default)
Twitter CardNot detected

Social Sharing Preview

2 fields

robots.txt (opens in a new tab)

115 rules
All bots 1 allowed · 61 disallowed
  • Allow/
  • Disallow/admin
  • Disallow/alpha
  • Disallow/attachment
  • Disallow/comments/with
  • Disallow/contest
  • Disallow/contestInvitation
  • Disallow/contestRegistrants
  • Disallow/contestRegistration
  • Disallow/contests/with
  • Disallow/css
  • Disallow/data
  • Disallow/enter
  • Disallow/gifts
  • Disallow/trustList
  • Disallow/group
  • Disallow/gym/edit
  • Disallow/images
  • Disallow/js
  • Disallow/list/view
  • Disallow/lists
  • Disallow/lists/edit
  • Disallow/lists/new
  • Disallow/logout
  • Disallow/markitup
  • Disallow/mashups
  • Disallow/modules
  • Disallow/printEntry
  • Disallow/problemset/standings
  • Disallow/problemset/status
  • Disallow/problemset/submit
  • Disallow/proposals
  • Disallow/ratings
  • Disallow/ratings/page
  • Disallow/recent-actions
  • Disallow/register
  • Disallow/renderer
  • Disallow/site
  • Disallow/scripts
  • Disallow/search
  • Disallow/settings
  • Disallow/society
  • Disallow/spectator
  • Disallow/st.codeforces.com
  • Disallow/submissions
  • Disallow*/submission/*
  • Disallow/support
  • Disallow/system
  • Disallow/teams/invite
  • Disallow/teams/with
  • Disallow/top-contributed
  • Disallow/u
  • Disallow/unsubscribe
  • Disallow/uploadfile
  • Disallow/user
  • Disallow/userForm
  • Disallow/userFormFieldValue/download
  • Disallow/userform
  • Disallow/userlist
  • Disallow/users
  • Disallow/usertalk
  • Disallow/verifyme
amazonbot 0 allowed · 2 disallowed
  • Disallow/
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applebot-extended 0 allowed · 1 disallowed
  • Disallow/
bytespider 0 allowed · 1 disallowed
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ccbot 0 allowed · 2 disallowed
  • Disallow/
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claudebot 0 allowed · 1 disallowed
  • Disallow/
cloudflarebrowserrenderingcrawler 0 allowed · 1 disallowed
  • Disallow/
google-extended 0 allowed · 2 disallowed
  • Disallow/
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gptbot 0 allowed · 2 disallowed
  • Disallow/
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meta-externalagent 0 allowed · 1 disallowed
  • Disallow/
mj12bot 0 allowed · 1 disallowed
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mediapartners-google 0 allowed · 1 disallowed
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israbot 0 allowed · 1 disallowed
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ubicrawler 0 allowed · 1 disallowed
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doc 0 allowed · 1 disallowed
  • Disallow/
zao 0 allowed · 1 disallowed
  • Disallow/
sitecheck.internetseer.com 0 allowed · 1 disallowed
  • Disallow/
zealbot 0 allowed · 1 disallowed
  • Disallow/
msiecrawler 0 allowed · 1 disallowed
  • Disallow/
sitesnagger 0 allowed · 1 disallowed
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webstripper 0 allowed · 1 disallowed
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webcopier 0 allowed · 1 disallowed
  • Disallow/
fetch 0 allowed · 1 disallowed
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offline explorer 0 allowed · 1 disallowed
  • Disallow/
teleport 0 allowed · 1 disallowed
  • Disallow/
teleportpro 0 allowed · 1 disallowed
  • Disallow/
webzip 0 allowed · 1 disallowed
  • Disallow/
linko 0 allowed · 1 disallowed
  • Disallow/
httrack 0 allowed · 1 disallowed
  • Disallow/
microsoft.url.control 0 allowed · 1 disallowed
  • Disallow/
xenu 0 allowed · 1 disallowed
  • Disallow/
larbin 0 allowed · 1 disallowed
  • Disallow/
libwww 0 allowed · 1 disallowed
  • Disallow/
zyborg 0 allowed · 1 disallowed
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download ninja 0 allowed · 1 disallowed
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fast 0 allowed · 1 disallowed
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grub-client 0 allowed · 1 disallowed
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k2spider 0 allowed · 1 disallowed
  • Disallow/
npbot 0 allowed · 1 disallowed
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webreaper 0 allowed · 1 disallowed
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omgilibot 0 allowed · 1 disallowed
  • Disallow/
chatgpt-user 0 allowed · 1 disallowed
  • Disallow/
openai-crawler 0 allowed · 1 disallowed
  • Disallow/
anthropic-ai 0 allowed · 1 disallowed
  • Disallow/
claude-web 0 allowed · 1 disallowed
  • Disallow/
perplexitybot 0 allowed · 1 disallowed
  • Disallow/
youbot 0 allowed · 1 disallowed
  • Disallow/
applebot 0 allowed · 1 disallowed
  • Disallow/
facebookexternalhit 0 allowed · 1 disallowed
  • Disallow/

Sitemaps

0

No sitemaps found

Registration details RDAP / WHOIS

RegistrarGandi SAS
Registered2009-04-10
Expires2027-04-10
Domain statusclient transfer prohibited
Nameserversfred.ns.cloudflare.com、jean.ns.cloudflare.com
DNSSECunsigned

DNS records

TypeNameValueTTLPriority
Acodeforces.com104.26.6.164286—
Acodeforces.com104.26.7.164286—
Acodeforces.com172.67.68.254286—
AAAAcodeforces.com2606:4700:20::681a:6a4288—
AAAAcodeforces.com2606:4700:20::681a:7a4288—
AAAAcodeforces.com2606:4700:20::ac43:44fe288—
MXcodeforces.commx.yandex.net30010
NScodeforces.comfred.ns.cloudflare.com86400—
NScodeforces.comjean.ns.cloudflare.com86400—
TXTcodeforces.comgoogle-site-verification=l4G0k0hCtL44oR2JYae12tG2VSyD0ig5OEN4oKGz6IY300—
TXTcodeforces.comloaderio=17e74635884b3872197928c7ea0123c5300—
TXTcodeforces.comv=spf1 ip4:77.234.204.67 ip4:95.163.252.67 ip4:195.123.220.85 include:_spf.yandex.net -all300—
DMARC_dmarc.codeforces.comv=DMARC1; p=reject300—

TLS and certificates

AssessmentNormal configuration
Supported protocolsTLSv1.2、TLSv1.3
Negotiated protocolTLSv1.3
Certificate subjectcodeforces.com
IssuerGoogle Trust Services
Valid until2026-11-27T12:39 · Remaining when checked: 87 days
Verification detailsCertificate trust: Passed · Hostname match: Passed

HTTP response headers

HeaderValue
content-typetext/html;charset=UTF-8
cache-controlprivate, no-cache, no-store, max-age=0, must-revalidate
servercloudflare
strict-transport-securitymax-age=86400
x-frame-optionssameorigin
x-content-type-optionsnosniff
set-cookieRedacted

Identified technologies

Google AnalyticsCloudflare

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