> 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/interfaces/interfaces.md).

# Overview

The Nexus Exchange is API-first: everything a trader can do is available programmatically. The **Interfaces** are the officially supported clients for that API — a machine-readable OpenAPI specification, language SDKs, a command-line tool, and an MCP server for AI agents. All of them speak to the same REST and WebSocket gateway documented under [APIs & Rates](/exchange/apis-and-rates.md); pick whichever fits how you build.

### The OpenAPI specification

The API is contract-first. The machine-readable schema — every route, request/response body, and CCXT method mapping — is published at [`nexus-xyz/nexus-exchange-api`](https://github.com/nexus-xyz/nexus-exchange-api) and served live at `/openapi.json`. Releases are tracked on [GitHub Releases](https://github.com/nexus-xyz/nexus-exchange-api/releases). The SDKs, CLI, and MCP server below are all generated from — or pinned to — a released version of this spec, so they stay in lockstep with the gateway.

### SDKs

| Language   | Repository                                                            | Use it for                                       |
| ---------- | --------------------------------------------------------------------- | ------------------------------------------------ |
| Rust       | [`nexus-exchange-rs`](https://github.com/nexus-xyz/nexus-exchange-rs) | Latency-sensitive clients and market-making bots |
| TypeScript | [`nexus-exchange-ts`](https://github.com/nexus-xyz/nexus-exchange-ts) | Web, Node, and edge applications                 |
| Python     | [`nexus-exchange-py`](https://github.com/nexus-xyz/nexus-exchange-py) | Research, backtesting, and scripting             |

Each SDK handles request signing (HMAC), pagination, and the WebSocket subscription lifecycle so you don't reimplement them. Version support and breaking-change policy are documented in each repository's README.

For the account and portfolio surface — consolidated account state, the withdrawable balance, the fee schedule, enriched position risk fields, and the equity/PnL/volume time-series — see [Portfolio & Account State](/interfaces/portfolio.md), which covers all four interfaces together.

### Command line

The [`nexus-exchange-cli`](https://github.com/nexus-xyz/nexus-exchange-cli) wraps the same API for interactive use and shell scripting — manage keys, place and cancel orders, and query account state without writing code. `nexus --version` reports the API spec and SDK versions it is built against.

### MCP server

The [`nexus-exchange-mcp`](https://github.com/nexus-xyz/nexus-exchange-mcp) server exposes the Exchange as [Model Context Protocol](https://modelcontextprotocol.io) tools, so an AI assistant or agent can trade and read account state through the same authenticated API a human client uses.

### Choosing a network

The Exchange runs on **Nexus Testnet** today as a development preview, with a public **mainnet** to follow. Every interface targets one network at a time, selected by the gateway base URL it is pointed at — see [APIs & Rates](/exchange/apis-and-rates.md) for the current base URL and the [Quickstart](/exchange/trading/quickstart.md) for the end-to-end connection flow. Credentials are scoped to the network they are created on: a testnet API key is not valid against mainnet, and vice versa.

### Authentication

Authentication is identical across every interface. You sign a fixed message with your wallet (EIP-191) to obtain a short-lived session token, use that token once to mint an HMAC API key, then sign each trading request with that key. The SDKs and CLI perform the request signing for you. The full walkthrough, with runnable examples, is in the [Quickstart](/exchange/trading/quickstart.md).

> **Status:** development preview on testnet. The interfaces track the OpenAPI spec release-by-release; pin to a spec version in production and consult each repository's release notes before upgrading. Testnet credentials and balances have no real-world value.


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