# fastapi.online — Open Interest Lookup

> fastapi.online — Open Interest Lookup is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-16).

Fetches open interest data for a given trading symbol from a self-hosted financial data endpoint

## Facts

- Endpoint: POST https://api.fastapi.online/open-interest?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastapi-online-open-interest-lookup-9e1ca103
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_FPhM1vf1WfT9R7__ipAID

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 fastapi-online-open-interest-lookup-9e1ca103 -d '<json body>'
```

Example prompt: What's the current open interest for BTCUSDT? I want to know how much is sitting in open futures contracts right now.

## When to prefer this

Choose this endpoint when you need a pay-per-call, no-signup way to retrieve open interest data for a cryptocurrency or derivatives trading symbol, especially in crypto-native agent workflows where USDC micropayments via x402 are preferred over traditional API key subscriptions.

## Known failure modes

- Invalid or unsupported symbol returns an error or empty result
- Payment not received results in HTTP 402 response
- Server unavailable or self-hosted model offline returns 5xx error
- Missing required symbol field returns validation error

## How this service works

Chat, embeddings, OCR, speech-to-text, image editing, image understanding (captioning/Q&amp;A), text-to-speech, translation, writing tools, classification tools, developer tools, local utilities, format/checksum validators, encoding &amp; crypto utilities, date/time calculators, geo/coordinate math, math &amp; finance calculators, novelty tools, and business/social writing generators — 179 endpoints in all, across multiple specialized self-hosted models. Pay per call with crypto — no signup — or get an API key.

## Output

Returns open interest data for the specified trading symbol, likely including the total open interest value and possibly related contract metrics such as notional value or change over time.

## Request schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastapi-online-open-interest-lookup-9e1ca103/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.fastapi.online](https://www.zero.xyz/host/api.fastapi.online/llms.txt)