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API · /codeforces-api

Codeforces API

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Codeforces as an API — the largest competitive-programming platform, running regular rated rounds for hundreds of thousands of programmers worldwide. This API wraps the official Codeforces API into a clean, predictable JSON service. /v1/user looks up one or many competitors' profiles — current and maximum rating with the corresponding rank/title (from newbie through grandmaster to legendary grandmaster), contribution score, country, city, organization, registration date and avatar. /v1/rating returns a competitor's full rating history, contest by contest, with the old and new rating, the rating change and the rank achieved in each round — ideal for plotting a rating curve. /v1/contests lists upcoming and past contests, filterable by phase (BEFORE for the schedule of upcoming rounds, FINISHED for the archive), each with start time, duration and type. /v1/problems searches the entire Codeforces problemset by tag (dp, graphs, greedy, math, implementation, data structures and dozens more) and by difficulty-rating range, returning each problem's contest id, index, name, difficulty rating and tags with a direct link. Ratings range from ~800 to 3500+. Ideal for competitive-programming dashboards, rating trackers, training and problem-recommendation tools, and Discord/Telegram bots for CP communities. Data from the official Codeforces API, free to use. The service is resilient to Codeforces' concurrency rate-limit (automatic retry with backoff).

#codeforces #competitive-programming #algorithms #programming-contests #developer-tools #ratings #problemset
api.oanor.com/codeforces-api
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Machine-readable spec so AI agents can integrate this API.

/api/codeforces-api/openapi.json
/api/codeforces-api/llms.txt

Discovery: GET /api/index.json lists every API.

API health

healthy
Uptime
100.00%
Server probes · 24h
Avg latency
293 ms
Server probes · 24h
Subscribers
4,064
active
Total calls
10
last 7 days
status Full status page → · 15 probes/24h

Pricing

Pick a tier — billed monthly, cancel anytime.

Free

Free

  • 1,000 calls / month
  • 2 requests / second
  • Hard cap (429 above quota, no overage)
  • 1000 calls/month
  • 2 req/sec
  • Profiles, ratings, contests & problems
  • No credit card
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Starter

€8.00 /month

  • 30,000 calls / month
  • 5 requests / second
  • Hard cap (429 above quota, no overage)
  • 30k calls/month
  • 5 req/sec
  • Full rating history
  • Email support
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Pro

€24.00 /month

  • 130,000 calls / month
  • 12 requests / second
  • Hard cap (429 above quota, no overage)
  • 130k calls/month
  • 12 req/sec
  • Problemset search & dashboards
  • Priority support
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Mega

€64.00 /month

  • 520,000 calls / month
  • 35 requests / second
  • Hard cap (429 above quota, no overage)
  • 520k calls/month
  • 35 req/sec
  • High-volume bots & trackers
  • Dedicated SLA
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ads.txt API

Fetch and evaluate any publisher's ads.txt / app-ads.txt — the IAB authorized-digital-sellers standard. Pass a domain and the check endpoint fetches its ads.txt server-side, then returns every seller record parsed into its fields — advertising system, the publisher's seller/account id, the DIRECT or RESELLER relationship and the optional certification-authority id (TAG-ID) — alongside counts (direct, reseller, distinct ad systems) and the declared variables OWNERDOMAIN, MANAGERDOMAIN, CONTACT and SUBDOMAINS. The verify endpoint answers the one question programmatic-advertising integrations actually ask: is this advertising system, with this publisher id, authorized to sell this domain's inventory? — returning an authorized boolean and the matching records. A missing file is reported as found:false (not an error), and soft-404 HTML pages are detected and rejected so you never parse a "page not found" as records. The request is made server-side and private or internal targets are refused (SSRF-guarded). Built for ad-tech supply-chain verification, SSP/DSP onboarding checks, anti-fraud and inventory audits. An ads.txt seller-authorization checker — distinct from the security-contact file reader (securitytxt), the robots.txt crawlability evaluator (robots) and the sitemap parser (sitemap). No upstream key, no cache.

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Sitemap API

Fetch and parse an XML sitemap (the sitemaps.org protocol). Pass a sitemap URL and the parse endpoint fetches it — following redirects and transparently gunzipping .gz sitemaps — and returns its type: a urlset with every URL and its lastmod, changefreq and priority, or a sitemapindex listing the child sitemaps, with offset/limit paging for large files. The urls endpoint goes further: when the sitemap is an index it fetches the child sitemaps too and flattens every page URL into a single list, with a configurable cap on URLs and child sitemaps and a truncated flag so you stay in control. The request is made server-side and private or internal targets are refused (SSRF-guarded). Built for SEO audits, building crawl queues and content inventories, change monitoring and migration checks. A sitemap fetcher and parser — distinct from generic XML-to-JSON conversion (xml), the robots.txt evaluator (robots) and the on-page SEO audit (seo). No upstream key, no cache.

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Count and split text the way people actually read it, using Unicode-correct segmentation. The count endpoint returns the number of grapheme clusters — the real, user-perceived characters, so a family emoji counts as 1 (not 7) and an accented letter as 1 — alongside words, sentences, code points, UTF-16 code units (the naive string length that over-counts) and UTF-8 byte length. This is exactly what character-limit fields, tweet/SMS counters and validation need so the count agrees with what the user sees. The segment endpoint splits text into grapheme, word or sentence segments (word segments are flagged word-like versus punctuation and spaces) and is locale-aware, so Japanese, Chinese and Thai word boundaries come out right. Everything is computed locally with no network calls. A Unicode text segmenter — distinct from the Unicode codepoint database (unicode), the case/text-utilities toolkit (text) and string similarity (similarity). No upstream key, no cache.

api.oanor.com/segmenter-api

Frequently asked questions

Quick answers about pricing, quotas, and integration.

How do I get an API key for Codeforces API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Codeforces API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Codeforces API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Codeforces API cost?
Codeforces API has a free tier with 100 calls / month. Paid plans start at €8.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Codeforces API GDPR-compliant?
All requests to Codeforces API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.

Pick an endpoint from the list on the left to see its details and try it.

Code snippets

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curl https://api.oanor.com/codeforces-api/SOME_PATH \
  -H "x-oanor-key: oanor_test_..."
const res = await fetch("https://api.oanor.com/codeforces-api/SOME_PATH", {
  headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();
$ch = curl_init("https://api.oanor.com/codeforces-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);
import requests
r = requests.get(
    "https://api.oanor.com/codeforces-api/SOME_PATH",
    headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())

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