Epic Online Services (EOS) API
Epic Online Services (EOS) is Epic Games' cross-platform SDK and REST API suite providing authentication, friends, achievements, stats, leaderboards, matchmaking, lobbies, voice, anti-cheat, and player data for games. Includes the Epic Games Store Web API for catalog and entitlement data. Designed for game developers integrating online services into their own titles.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
HTTPS enforced. OAuth 2.0 with client credentials is standard and well-implemented. EOS Connect cross-platform identity tokens provide reasonable security isolation. Client Secret handling is a developer responsibility with clear guidance. No IP allowlisting or additional security controls documented.
⚡ Reliability
Best When
You are a game developer integrating online features (auth, achievements, friends, matchmaking) into a title and want cross-platform coverage including Epic Games Store, Steam, and console support.
Avoid When
You want to query Epic Games or player data from outside a game context — EOS is a developer toolkit, not an open data API. Use Epic's unofficial store endpoints for catalog scraping (unsupported).
Use Cases
- • Adding cross-platform achievements and stats to a game using EOS SDK
- • Implementing cross-platform friends lists spanning Epic, Steam, and Xbox accounts
- • Querying the Epic Games Store catalog for game metadata and pricing
- • Implementing player auth via Epic Account Services with cross-platform identity
- • Matchmaking and lobby management for multiplayer games
Not For
- • Reading other developers' game data without their SDK integration
- • Consumer-facing player stats lookups (API is game-developer-facing, not end-user-facing)
- • Simple REST-only integrations — core EOS functionality requires the native C SDK
- • Non-game applications (EOS ToS restricts use to games and game tools)
Interface
Authentication
Two auth systems: Epic Account Services (for player-facing auth with Epic accounts, social features) and EOS Connect (for cross-platform identity via Steam, Xbox, PSN, etc.). Both require client credentials (Client ID + Client Secret) registered in the Epic Developer Portal. Client credentials auth for server-side calls. OAuth 2.0 for user-facing flows. Token exchange between external identity providers and EOS Connect adds complexity.
Pricing
EOS SDK and APIs are free to use. Epic Games Store has a 12% revenue share for games sold through the store. No per-API-call charges for EOS services.
Agent Metadata
Known Gotchas
- ⚠ Core EOS functionality (achievements, stats, matchmaking) is SDK-first — REST-only access is limited, forcing agents to either use the C SDK via FFI or accept reduced functionality
- ⚠ Two separate identity systems (Epic Account Services vs EOS Connect) must both be configured for full cross-platform support, with different token flows for each
- ⚠ Client Secret must be protected server-side — client-side exposure is a common mistake in EOS integrations
- ⚠ Product ID, Sandbox ID, and Deployment ID are three separate identifiers all required for most API calls — missing or swapped IDs cause confusing auth failures
- ⚠ Rate limits are not publicly documented, making it difficult to design reliable agent retry strategies
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for Epic Online Services (EOS) API.
Scores are editorial opinions as of 2026-03-06.