SDKs overview

Codeforces, a platform for competitive programming, offers an official API that allows developers to interact with its services programmatically. This API facilitates access to contest information, problem statements, user submissions, and other data without direct web scraping. While Codeforces provides a direct HTTP API, community-driven SDKs and libraries abstract these HTTP requests into language-specific functions, simplifying development.

The Codeforces API is designed for read-only access to public data and authenticated access for user-specific information. It supports various methods for fetching contest lists, problem details, submission statuses, and user ratings. The API typically returns data in JSON format, aligning with common web service practices for data exchange, as described by the W3C's recommendations for data formats.

Developers use these SDKs and libraries to build custom tools, bots, and analytics dashboards. Examples include applications that automatically fetch new problems, track friends' contest performance, or create personalized practice routines based on problem tags and difficulty. The ecosystem benefits from both official API access and substantial community contributions that extend its utility.

Official SDKs by language

Codeforces does not officially provide traditional Software Development Kits (SDKs) in the form of installable packages for specific programming languages. Instead, it offers a public API specification that developers can use to build their own clients. The API documentation outlines the available methods, parameters, and expected responses, allowing integration from any language capable of making HTTP requests and parsing JSON.

However, the concept of an "official SDK" for Codeforces often refers to direct usage of their documented API endpoints. The platform emphasizes direct API interaction rather than providing pre-packaged libraries. This approach gives developers flexibility in choosing their preferred HTTP client and JSON parsing libraries. For example, a Python developer might use requests for HTTP and json for parsing, while a Java developer might use HttpClient and Jackson, following general web API interaction patterns.

Given the absence of official client libraries, the following table illustrates how one might conceptualize "official" interaction using direct API calls:

Language Concept Installation (Conceptual) Maturity
Python Direct HTTP client (e.g., requests) + JSON parsing pip install requests Stable (depends on underlying HTTP library)
Java HTTP client (e.g., java.net.http or Apache HttpClient) + JSON parsing (e.g., Jackson) Add dependencies to pom.xml or build.gradle Stable (depends on underlying HTTP library)
JavaScript (Node.js) Direct HTTP client (e.g., node-fetch or built-in https) + JSON parsing npm install node-fetch (if not using built-in) Stable (depends on underlying HTTP library)
C++ HTTP client library (e.g., cURLpp, Boost.Asio) + JSON parsing (e.g., nlohmann/json) Install via package manager (e.g., Conan, vcpkg) Stable (depends on underlying HTTP library)

Installation

Since Codeforces does not distribute official SDKs, installation typically involves setting up a development environment with standard HTTP client and JSON parsing libraries for your chosen programming language. The steps below illustrate common installation patterns for interacting with the Codeforces API directly or through community-contributed wrappers.

Python

For Python, the requests library is a common choice for making HTTP requests:

pip install requests

The built-in json module handles JSON parsing and does not require separate installation.

Java

For Java projects, you might use the built-in java.net.http.HttpClient (Java 11+) or a third-party library like Apache HttpClient. For JSON parsing, Jackson or Gson are popular choices. If using Maven, add dependencies to your pom.xml:

<dependencies>
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.13</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.13.0</version>
    </dependency>
</dependencies>

JavaScript (Node.js)

In Node.js, you can use the built-in https module or node-fetch for a browser-like fetch API experience:

npm install node-fetch@2 # For older Node.js versions, v3+ is ESM only

The built-in JSON object handles parsing.

C++

C++ requires external libraries for both HTTP requests and JSON parsing. curlpp (a C++ wrapper for libcurl) and nlohmann/json are common choices. Installation varies by operating system and package manager:

# Example for Ubuntu/Debian
sudo apt-get install libcurlpp-dev libnlohmann-json-dev

# Or via a package manager like Conan or vcpkg

For specific community libraries, refer to their individual documentation for installation instructions.

Quickstart example

This Python example demonstrates fetching the latest contest list from the Codeforces API. It uses the requests library to make an HTTP GET request and the built-in json module to parse the response.

import requests
import json

# Base URL for the Codeforces API
BASE_URL = "https://codeforces.com/api/"

def get_recent_contests():
    """Fetches and prints a list of recent Codeforces contests."""
    endpoint = "contest.list"
    url = f"{BASE_URL}{endpoint}"

    try:
        response = requests.get(url)
        response.raise_for_status()  # Raise an HTTPError for bad responses (4xx or 5xx)
        data = response.json()

        if data["status"] == "OK":
            contests = data["result"]
            print("Recent Codeforces Contests:")
            # Filter for upcoming or running contests for brevity
            active_contests = [c for c in contests if c["phase"] == "BEFORE" or c["phase"] == "CODING"]
            
            if active_contests:
                for contest in active_contests:
                    print(f"  - {contest['name']} (ID: {contest['id']})")
            else:
                print("  No active or upcoming contests found currently.")
        else:
            print(f"API Error: {data['comment']}")

    except requests.exceptions.HTTPError as http_err:
        print(f"HTTP error occurred: {http_err}")
    except requests.exceptions.ConnectionError as conn_err:
        print(f"Connection error occurred: {conn_err}")
    except requests.exceptions.Timeout as timeout_err:
        print(f"Timeout error occurred: {timeout_err}")
    except requests.exceptions.RequestException as req_err:
        print(f"An unexpected error occurred: {req_err}")
    except json.JSONDecodeError:
        print("Failed to decode JSON response.")

if __name__ == "__main__":
    get_recent_contests()

This script demonstrates a basic unauthenticated API call. For authenticated calls (e.g., submitting solutions or accessing private user data), you would need to include an API key and secret, as detailed in the Codeforces API documentation.

Community libraries

Due to the absence of official language-specific SDKs, the Codeforces community has developed various libraries and wrappers to simplify API interaction. These libraries often provide a more object-oriented or idiomatic interface for different programming languages, abstracting the direct HTTP requests and JSON parsing.

Some notable community-contributed libraries include:

  • Python: Several Python wrappers exist, such as codeforces-api (available on PyPI), which aims to provide a comprehensive client for the Codeforces API. These libraries often handle authentication, request signing, and rate limiting.
  • Java: Community efforts in Java typically involve creating client libraries that mirror the API structure, making it easier for Java developers to integrate Codeforces data into their applications.
  • JavaScript/TypeScript: Libraries for Node.js environments allow developers to build serverside applications or bots that interact with Codeforces. These often leverage modern JavaScript features like async/await for asynchronous operations.
  • Go: Go language bindings for the Codeforces API are also available, enabling efficient and concurrent access to the platform's data.

When choosing a community library, it is advisable to check its maintenance status, documentation, and community support. Resources like GitHub often host these projects, where you can review issues, pull requests, and recent commit activity to gauge their reliability and ongoing development. The Codeforces API blog post often links to community projects, or you can find them via language-specific package managers and GitHub searches.

These community libraries demonstrate the extensibility of the Codeforces platform and the initiative of its user base to create tools that enhance the competitive programming experience. They contribute to a richer development ecosystem around Codeforces, allowing for a wider range of applications and integrations, similar to how Google's open-source libraries support its various APIs.