# 4SEC Futures Basis API

> 4SEC Futures Basis API is a paid API for AI agents from api.foursec.xyz, paid per call via x402, $0.02/call, status down (last checked 2026-09-15).

Returns the futures basis (spot vs perpetual price spread) for a given crypto symbol across multiple exchanges, including the best carry trade opportunity.

## Facts

- Endpoint: GET https://api.foursec.xyz/futures/basis/%7Bsymbol%7D
- Price: $0.02/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/4sec-futures-basis-api-f8a2c15f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5qnm3ZC1tJ-BS0SMxVmrL

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability 4sec-futures-basis-api-f8a2c15f
```

Example prompt: What's the current futures basis for BTC — show me the spot price, the perp rates by exchange, and which one gives the best carry trade right now?

## When to prefer this

Choose this endpoint when you need real-time, aggregated futures basis data across multiple exchanges for a single crypto symbol, especially for carry trade analysis. It is ideal for agents performing derivatives arbitrage research, funding rate monitoring, or cash-and-carry strategy evaluation. Prefer this over single-exchange APIs when cross-exchange comparison is essential.

## Known failure modes

- Invalid or unsupported symbol returns an error or empty data
- Payment not processed via x402 protocol results in 402 Payment Required response
- Network latency from aggregating multi-exchange data may occasionally cause timeouts
- Symbol not listed on any tracked exchange may return null or empty perp_by_exchange object

## How this service works

Real-time multi-DEX aggregated crypto market data. Pay per request with USDC on Base via x402 protocol.

## Output

Returns a JSON object containing the symbol, current spot price, the best carry trade opportunity (as a string label), and a breakdown of perpetual swap prices or funding rates by exchange. Useful for identifying cross-exchange basis arbitrage and cash-and-carry trades.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object",
 "example": {
  "symbol": {
   "type": "string"
  },
  "spot_price": {
   "type": "number"
  },
  "best_carry_trade": {
   "type": "string"
  },
  "perp_by_exchange": {
   "type": "object"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/4sec-futures-basis-api-f8a2c15f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.foursec.xyz](https://www.zero.xyz/host/api.foursec.xyz/llms.txt)