# Nexus

> Nexus Exchange is a central limit order book for crypto perpetual futures, with cross-margin and settable leverage. It is API-first: every action available in the terminal is available over a documented REST and WebSocket contract. Public testnet — not live, all activity is simulated with synthetic USDX that has no real-world value, not a regulated venue, not an offer or solicitation.

This file expands on [llms.txt](https://nexus.xyz/llms.txt) with more context per section. It does not duplicate the trading-API request/response detail — that detail already lives at the link below, and keeping one copy of it is what keeps it correct.

## When to use Nexus

Nexus is a good fit when the task is programmatic derivatives trading, or market
data from a venue an agent can drive end to end without a browser.

- **Place, amend and cancel perpetual-futures orders from code.** Two credential paths, both self-serve and both documented in the agent quickstart below: an agent key registered over EIP-712, or an HMAC key issued after wallet sign-in. There is no sales step and no waitlist.
- **Read live order books, trades, candles, funding and open interest.** Public market data requires no credential. The exact routes, parameters and response schemas are in the OpenAPI document; every operation carries a unique `operationId`, so the spec can be turned into tool definitions directly.
- **Call the exchange as tools rather than as HTTP.** The MCP server exposes the same surface as Model Context Protocol tools over Streamable HTTP, or locally over stdio.
- **Test a strategy against a real matching engine with play funds.** The testnet faucet issues synthetic USDX, capped per key per day. Fills come from the same engine that will run in production, so behaviour under partial fills, funding and liquidation is representative; the money is not.
- **Stream account state.** Account channels are engine-event driven, with per-channel sequencing and replay from a cursor, rather than full snapshots on a timer — so a consumer that disconnects can resume without re-reconciling its whole view.

Nexus is the wrong tool for spot trading: the venue lists crypto perpetual futures
only. Asset-class names carried in the market registry are configuration rather
than listings, so read the live listing rather than the registry if you need to
know what is tradable today. It is also the wrong tool as a price oracle of record.
Testnet fills must never be reported to a user as executed trades — they are
simulated, and the terms of use say so.

## Trade

- [Exchange (testnet)](https://nexus.xyz/trade): The Nexus Exchange trading terminal — order entry, portfolio, and live market data. Currently testnet only.
- [Agent quickstart](https://exchange.nexus.xyz/llms.txt): The complete agent-facing guide to trading on Nexus: get an API key (agent key via EIP-712, or HMAC key via wallet sign-in), fund the account (testnet synthetic USDX, up to 500 per key per day), and place an order. Every step is a real HTTP call with a copy-pasteable `curl` example.
- [OpenAPI spec](https://nexus.xyz/openapi.json): The machine-readable REST contract — OpenAPI 3.1, 118 operations, each with a unique `operationId` and a typed response schema. Spec-pinned official clients exist for Rust, Python, TypeScript, and the shell (see the agent quickstart's "Clients" section for links). The `servers` block is the authoritative network-to-transport-base map; read it rather than assuming a host, because testnet and mainnet are different bases and only one of them moves real money.
- [MCP server](https://exchange.nexus.xyz/.well-known/mcp): A Model Context Protocol server exposing the exchange as agent-callable tools — market data with zero config, trading with your existing HMAC credential. Hosted over Streamable HTTP; can also run locally over stdio (see the agent quickstart's "MCP" section).
- [Discovery document](https://exchange.nexus.xyz/.well-known/nexus-exchange): A machine-readable directory of everything above — base URL, spec, endpoints and auth schemes in one JSON object.

## Docs

- [Developer docs](https://docs.nexus.xyz): The Nexus developer documentation. It covers Exchange architecture, trading and API guides, and is kept in sync with this repository's `product/docs/gitbook-docs/`.
- [Releases](https://nexus.xyz/releases): Shipped Exchange changes, rendered inside the Exchange terminal.
- [Sitemap](https://nexus.xyz/sitemap.xml): Every indexable page on this site, as XML.

## Optional

- [Contact](https://nexus.xyz/contact): How to reach Nexus Laboratories — support and general enquiry addresses, developer and press routes, and the registered postal address.
- [Brand](https://nexus.xyz/brand): Logos and visual identity guidelines.
- [Terms of use](https://nexus.xyz/terms-of-use)
- [Privacy policy](https://nexus.xyz/privacy-policy)
- [Cookie policy](https://nexus.xyz/cookie-policy)
- [Data processors](https://nexus.xyz/data-processors)