Introduction

With Codeforces API you can get access to some of our data in machine-readable JSON format.

To access the data you just send a HTTP-request to address https://codeforces.net/api/{methodName} with method-specific parameters. Each method description has an example URL.

Each method call returns a JSON-object with three possible fields: status, comment and result.

  • Status is either "OK" or "FAILED".
  • If status is "FAILED" then comment contains the reason why the request failed. If status is "OK", then there is no comment.
  • If status is "OK" then result contains method-dependent JSON-element which will be described for each method separately. If status is "FAILED", then there is no result.

API may be requested at most 1 time per two seconds. If you send more requests, you will receive a response with "FAILED" status and "Call limit exceeded" comment.

Language-depended fields like names or descriptions will be returned in the default language. Also, you can pass additional parameter lang with values en and ru to select the language of the result.

Authorization

All methods can be requested anonymously. This way only public data will be accessable via API. To access data, private for some user (e.g. hacks during the contest), API key must be generated on https://codeforces.net/settings/api page. Each API key has two parameters: key and secret. To use the key you must add following parameters to your request.

  1. apiKey — it must be equal to key
  2. time — current time in unix format (e.g., System.currentTimeMillis()/1000). If the difference between server time and time, specified in parameter, will be greater than 5 minutes, request will be denied.
  3. apiSig — signature to ensure that you know both key and secret. First six characters of the apiSig parameter can be arbitrary. We recommend to choose them at random for each request. Let's denote them as rand. The rest of the parameter is hexadecimal representation of SHA-512 hash-code of the following string: <rand>/<methodName>?param1=value1&param2=value2...&paramN=valueN#<secret> where (param_1, value_1), (param_2, value_2),..., (param_n, value_n) are all the request parameters (including apiKey, time, but excluding apiSig) with corresponding values, sorted lexicographically first by param_i, then by value_i.

For example:

If your key is xxx, secret is yyy, chosen rand is 123456 and you want to access method contest.hacks for contest 566, you should compose request like this: https://codeforces.net/api/contest.hacks?contestId=566&apiKey=xxx&time=1735011919&apiSig=123456<hash>, where <hash> is sha512Hex(123456/contest.hacks?apiKey=xxx&contestId=566&time=1735011919#yyy)

JSONP

JSONP is supported. Add jsonp parameter to the query and the result will be returned as JavaScript function call.

For example, if jsonp parameter is parseResponse and method returned object {"status":"OK","response":"..."}, then final result is parseResponse({"status":"OK","response":"..."});.