Codeforces vs Hackerearth

Codeforces exposes a JSON API over its own contest and user database, covering problems, contests, submissions, ratings, and hacks through methods like contest.standings, user.info, and problemset.problems. Most methods are fully public and callable with no key at all — a live call to user.info returned real rating and rank data with zero authentication — while a handful of privacy-sensitive methods (e.g. user.friends) require a signed apiKey/apiSig pair generated from a registered account. There's no paid tier or usage fee; the service is entirely free.

HackerEarth's v4 Code Evaluation API lets registered client applications submit source code in dozens of languages for asynchronous sandboxed compilation and execution, returning results via a callback URL rather than a blocking response. Every call must carry a client-secret issued after registering a web application, confirmed live by a real request that failed with "client_secret is needed!" rather than any generic error. HackerEarth's own docs describe a cap on both the number of registered clients and the number of free requests per account, with no public self-serve pricing page — consistent with a freemium model gated behind manual registration rather than an open paid tier.