# Order book · API reference · Femtos

> L2 book of one market with order counts, from our node. GET /v1/book on HyperCore: parameters, response fields and a live call per layer.

- Base URL: `https://api.femtos.xyz/v1` (REST) · `wss://api.femtos.xyz/v1/ws` (WebSocket) · MCP: `https://api.femtos.xyz/mcp`
- Auth: `Authorization: Bearer $FEMTOS_KEY`. Free key: https://femtos.xyz/account/new (browser), or with
  no browser: `GET https://femtos.xyz/accounts/agent/challenge`, solve its proof of work, then `POST https://femtos.xyz/accounts/agent/signup`
  (https://femtos.xyz/agents.md#agent-onboarding)
- Decimals are exact strings, times Unix milliseconds, addresses lowercase `0x`
- Whole API in one file: https://femtos.xyz/agents.md · OpenAPI: https://api.femtos.xyz/v1/openapi.json · Index: https://femtos.xyz/llms.txt
- Page with live calls: https://femtos.xyz/reference/book

## Order book — GET `/v1/book`

L2 book of one market with order counts, from our node.

Layers: HyperCore. Not on Elysium or HyperEVM: the EVM layers trade on AMM pools, with no order book: pool detail and liquidity events cover a pool.
Page with live calls: https://femtos.xyz/reference/book?layer=hypercore

| Param | In | Example or values | Meaning |
|---|---|---|---|
| `coin` | query | `BTC` | HyperCore coin (perp name, spot @index, HIP-3 dex:COIN) |
| `depth` | query | `20` | Levels per side |

```bash
curl -H "Authorization: Bearer $FEMTOS_KEY" "https://api.femtos.xyz/v1/book?coin=BTC&depth=20"
```

| Field | Type | Meaning |
|---|---|---|
| `height` | int | Block of the book |
| `bids` | [string, string, int][] | Bid levels, best first: [px, sz, n] = price, size (exact decimal strings), order count |
| `asks` | [string, string, int][] | Ask levels, best first: [px, sz, n] |

## Related (Market data)

- [Markets](https://femtos.xyz/reference/markets.md) `GET /v1/markets`: Every tradable perp, spot, HIP-3 and outcome market with 24 h stats. (Elysium, HyperCore, HyperEVM)
- [Candles](https://femtos.xyz/reference/candles.md) `GET /v1/candles`: OHLCV of any HyperCore market down to 1 s, ascending, UTC-aligned. (Elysium, HyperCore, HyperEVM)
- [Forming candle](https://femtos.xyz/reference/ws/candles.md) `WS elysium.candles · hc.candles · hyperevm.candles`: The forming candle, pushed once per block where it changes. (Elysium, HyperCore, HyperEVM)
- [Token candles](https://femtos.xyz/reference/token-candles.md) `GET /v1/candles`: OHLCV of a token through its USDC market (a perp coin: the perp). (Elysium, HyperCore, HyperEVM)
- [Trades](https://femtos.xyz/reference/trades.md) `GET /v1/trades`: Latest fills of one market, newest first. (Elysium, HyperCore, HyperEVM)
- [Trades stream](https://femtos.xyz/reference/ws/trades.md) `WS elysium.trades · hc.trades · hyperevm.trades`: All trades of one market as they happen: raced between our node and Hyperliquid's public feed, first copy sent, the other dropped. (Elysium, HyperCore, HyperEVM)
- [Book stream](https://femtos.xyz/reference/ws/book.md) `WS hc.book`: Full-depth book, then the levels each block changes. (HyperCore)
- [Best bid / offer](https://femtos.xyz/reference/ws/bbo.md) `WS hc.bbo`: Top of book of one market each block: raced between Hyperliquid's public feed and our node (newest block wins, our node corrects the same block). (HyperCore)
- [Order updates](https://femtos.xyz/reference/ws/orders.md) `WS hc.orders`: Every order status change, filterable by coin, user and status. (HyperCore)
- [Token prices](https://femtos.xyz/reference/prices.md) `GET /v1/prices`: USD price of up to 100 tokens in one call, each with its source and provenance. (Elysium, HyperCore, HyperEVM)
- [Price history](https://femtos.xyz/reference/price-history.md) `GET /v1/prices/history`: USD closes per unit of up to 25 tokens over a window, or the price of 100 tokens at one time (at=). (Elysium, HyperCore, HyperEVM)
- [HYPE price](https://femtos.xyz/reference/ws/prices.md) `WS prices.hype`: HYPE from the Hyperliquid oracle, perp mark and exchanges. (HyperCore)
- [Pool detail](https://femtos.xyz/reference/pool.md) `GET /v1/pools/{address}`: One pool: dex, fee, tokens, liquidity in USD, depth, 5m to 24h activity, top LPs. (Elysium, HyperEVM)
- [Liquidity events](https://femtos.xyz/reference/liquidity.md) `GET /v1/liquidity`: Liquidity added to and removed from one pool, newest first. (Elysium, HyperEVM)
- [Daily token volume](https://femtos.xyz/reference/volume.md) `GET /v1/volume`: USD swap volume of a token per UTC day, both sides of every priced swap. (Elysium, HyperEVM)

Every page: https://femtos.xyz/reference.md