dYdX vs Gemini

dYdX is a decentralized perpetuals exchange that migrated from its StarkEx-based v3 to a Cosmos-chain v4 architecture, replacing the old exchange API with an open-source Indexer exposing markets, orderbooks, trades, and candles over REST and WebSocket. Anyone can run their own Indexer instance, but the public one at indexer.dydx.trade needs no signup for market-data reads — it's rate-limited rather than API-key gated.

Gemini's REST and WebSocket APIs cover public market data (tickers, order books, trade history) alongside authenticated endpoints for order placement, account status, and FIX Drop Copy. Public market-data calls need no credentials, while trading and account endpoints require an HMAC-signed API key/secret pair with role-based permissions such as separate Trader and Fund Manager roles.