> For the complete documentation index, see [llms.txt](https://docs.nexus.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nexus.xyz/exchange/apis-and-rates.md).

# APIs & Rates

The Nexus Exchange is API-first. Everything a trader can do — fund an account, place and cancel orders, query positions, stream the order book — is available over REST and WebSocket. The web frontend is a read-only view; programmatic access is the primary interface.

### Base URL

```
https://exchange.nexus.xyz/api/exchange
```

This is the testnet preview gateway. The machine-readable OpenAPI specification is served at `/openapi.json` and versioned at [`nexus-xyz/nexus-exchange-api`](https://github.com/nexus-xyz/nexus-exchange-api); releases are tracked on [GitHub Releases](https://github.com/nexus-xyz/nexus-exchange-api/releases).

### Authentication model

There are two credential types:

1. **Session token (Bearer).** Created by signing a fixed message with your Ethereum wallet (EIP-191). Used **only** to create and manage API keys — never for trading. Expires after 24 hours.
2. **API key (HMAC).** A `key_id` + `secret` pair. Every trading and account request is signed with HMAC-SHA256 over a canonical request string. The secret is shown once at creation and cannot be retrieved later.

```
1. POST /auth/login   (wallet signature)        → session Bearer token
2. POST /keys         (Bearer)                   → API key_id + secret
3. sign each request  (HMAC over canonical str)  → trade
```

See the Quickstart for the full flow with runnable cURL.

### CCXT

CCXT-compatible **read** endpoints are available today (markets, tickers, order book, trades, balances, positions), tagged in the OpenAPI spec. Broader CCXT support, including order placement, is planned.

### Reference

* Quickstart: Your First Trade
* REST API Reference
* WebSocket API Reference
* Rate & Connection Limits
* [API Versioning](/exchange/apis-and-rates/api-versioning.md)

> **Status:** testnet preview. Credentials, sessions, and rate-limit state are not yet durable across gateway restarts — treat API keys as re-creatable. Production hardening is in progress.


---

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