# Perp holders · HyperCore API · Femtos

> Largest open positions of a perp, long and short.

- 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` (or `X-API-KEY: $FEMTOS_KEY`). Free key: https://femtos.xyz/accounts/ (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/hypercore/holders-positions

## Perp holders — GET `/v1/holders`

Largest open positions of a perp, long and short.

| Param | In | Example or values |
|---|---|---|
| `layer` | query | `hypercore` |
| `token` | query | `BTC` |
| `kind` | query | `positions`, `balances` |
| `limit` | query | `20` |

```bash
curl -H "Authorization: Bearer $FEMTOS_KEY" "https://api.femtos.xyz/v1/holders?layer=hypercore&token=BTC&kind=positions&limit=20"
```

| Field | Type | Meaning |
|---|---|---|
| `totalHolders` | int | positive balances, system excluded |
| `top10Share` | number \| null | 10 largest shares, 0–1 |
| `holders[]` | object | {address, amount, share, usd?, side?, label?} |
| `system[]` | object | bridge, pools, fee collector… (excludeSystem=0 to count them) |
| `asOf · height` | int | time and block of the balances |

## Related (Holders)

- [Token holders](https://femtos.xyz/hypercore/holders.md): Spot balances of a HyperCore token, largest first.
- [Token registry](https://femtos.xyz/hypercore/coins.md): HyperCore tokens with their HyperEVM contract and price.
- [Coin detail](https://femtos.xyz/hypercore/coin.md): One token: its links across layers, the markets it trades on, its 5 largest holders.

All HyperCore endpoints: https://femtos.xyz/hypercore.md