Verdict
atcoder.jp appears legitimate.
Our checks found nothing pointing to fraud. Ordinary care still applies when you pay or sign in.
| What this site appears to be | AtCoder official site: programming contest listings, rankings, announcements, and user account access. Primary purpose is contest hosting and community information. |
|---|
Evidence status and limitations
Evidence completeness: UNKNOWN
- The real-world operator identity was not independently verified.
- Module-level completeness metadata is unavailable for this legacy report.
At a glance
The checks that decide most of this verdict.
| Malware engines | None flagged itVirusTotal | Clear |
|---|---|---|
| Google Safe Browsing | Not listedGoogle | Clear |
| Abuse reports on the host | 0 reportsAbuseIPDB; shared hosting inflates this count | Noted |
| Domain age | 12 years oldRegistered history | Clear |
| Web archive | Never archivedNo public history of this site | Watch |
| Certificate | Encrypted connectionIssued by Amazon RSA 2048 M01 | Noted |
The page as captured
No screenshot is retained for this report.
Key findings
- Automated classification: Not Scam.
- Domain age: more than 10 years (registration continuity).
- No flags from the reputation services TrustSniffer consulted at assessment time.
Full analysis
Overview
AtCoder is an online programming contest and community platform that presents contest schedules, rankings, announcements, practice opportunities, and user account access; its apparent business model is community and contest operations rather than soliciting deposits or promising financial returns.
Scam/Impersonation Risk
No contradictions were observed. The homepage presents a coherent AtCoder-branded contest service, including recurring beginner, regular, heuristic, and library-practice contests, together with rankings and user ratings. The site does include sign-in and sign-up functionality, but the available analysis found no hidden forms, external password destinations, wallet activity, cloaking, brand-impersonation indicators, or other deceptive behavior. External reputation checks were clean, and the domain appears long-established. The real-world operator remains not independently verified, so the evidence supports an apparently legitimate established site rather than proving operator identity.
- Domain registration: 2014-11-15; age 11.75 years.
- The homepage was evaluated with 0 malicious and 0 suspicious detections, with no external blacklist or search-warning hit.
- Behavioral testing recorded 2 successful runs, 0 hidden forms, 0 external password forms, 0 wallet-provider detections, and 0 wallet-drainer runs.
- The homepage has an established global traffic presence, recorded at rank 13122 and within the top 1 million.
Regulatory Verification Notes
AtCoder’s observed function is a programming contest portal, not an investment, brokerage, payment, or deposit-taking service. No licensing claim or registration number was identified in the supplied page content; this is a limited disclosure gap rather than evidence of deception, particularly because the site does not present a financial-return business model. Available identity signals are consistent with an established website, but they do not independently confirm the legal entity operating it. The transport and hosting telemetry are technically consistent with a stable mainstream web service.
- The homepage identifies the service as “AtCoder” and provides contest listings, rankings, announcements, and account functions.
- The site’s TLS certificate is issued by Amazon RSA 2048 M01, uses DV validation, and is valid through 2026-10-16.
- The site’s observed hosting infrastructure is associated with Amazon.com, Inc., US, under AS16509.
- The recorded page-authority assessment is in the mid band, providing contextual support but not a regulatory or legal determination.
What to Verify Next
Before credential or payment interactions, an enterprise or user should independently confirm the operating entity through an official AtCoder-published channel and review the applicable privacy, account, and service terms. Any payment-related request should be checked for a clear transaction purpose and protected payment method; account users should also confirm that the browser address and certificate correspond to the intended domain. Official social channels should be reached through links from the site or another independently trusted source rather than through unsolicited messages.
- The homepage links to Facebook, Twitter, and Telegram social channels.
- The homepage’s stated service activity is contest hosting, rankings, and programming community participation.
- The supplied identity assessment classifies the operator connection as likely rather than independently verified.
Summary Verdict
Available evidence is consistent with an established, apparently legitimate website with a high-trust, low-risk posture and no observed scam or impersonation contradictions. The classification is well supported by the site’s coherent purpose, stable technical behavior, long operating history, and clean external reputation, while operator identity remains subject to ordinary independent confirmation.
Infrastructure Integrity
The website is protected by AWS CloudFront CDN/WAF infrastructure, with observed delivery through four Amazon edge addresses and no origin candidate visible in the analysis. The infrastructure resolved to AS16509, operated by Amazon.com, Inc., US; this is a mitigating security and availability signal, not proof of organizational legitimacy.
Closing Assessment
Normal browsing and routine contest participation are proportionate uses; credential or payment actions should follow the ordinary independent identity, terms, and payment-protection checks appropriate to the specific interaction.
Written analysis generated 2026-08-13 by the TrustSniffer Analysis Engine from the evidence in this report.
What the analysis found
No rule findings contributed to this verdict.
Identity verification
| Status | LIKELY |
|---|---|
| Identity score | 76/100 |
| Identity verification confidence | 76% |
- Trusted social count=2
Identity verification measures whether the site can be independently connected to a real-world brand or person. It is separate from the classification confidence.
What TrustSniffer observed
First-party facts recorded during the assessment of atcoder.jp.
- The request stayed on atcoder.jp. It was not redirected to another domain. Clear
- DNS for this domain is served by awsdns-12.com, across 4 name servers. Noted
- The registration is paid up to 2026-11-30. Noted
- It is hosted on AMAZON-02, from a server in US. Noted
Domain intelligence
| Registrar | Not available |
|---|---|
| Hosting | AMAZON-02 - Amazon.com, Inc., US |
| Country | US |
| Server IP | 13.33.235.127 |
| Name servers | ns-96.awsdns-12.com, ns-1144.awsdns-15.org, ns-890.awsdns-47.net, ns-1543.awsdns-00.co.uk |
| SSL issuer | Amazon RSA 2048 M01 |
| SSL expiry | 2026-10-16 |
| Domain age | 11.75 years (continuous registration) |
| Domain expiry | 2026-11-30 |
| Archive first seen | Not available |
| Archive snapshots | 0 |
| Reputation | VirusTotal: 0 flagged | AbuseIPDB: 0 reports | Google Safe Browsing: 0 matches |
About this assessment
A trust score summarises the evidence TrustSniffer could collect about atcoder.jp at assessment time. It is a starting point for your own judgement, not a guarantee: a high score means the signals were consistent with a legitimately operated site, a low or critical score means several risk patterns were present.
TrustSniffer assesses a website from the evidence it can collect at a point in time: domain registration and age, hosting and certificate, the content the site served, and third-party reputation feeds. A score is a summary of that evidence, not a guarantee and not a legal finding. There is no human rating and no user review in it. A site can change after it is assessed.