# CoinCap RSI (Relative Strength Index) Endpoint

> CoinCap RSI (Relative Strength Index) Endpoint is a paid API for AI agents from rest.coincap.io, paid per call via x402, $0.004/call, status unknown (last checked 2026-09-13).

Returns the Relative Strength Index (RSI) technical indicator for a specified cryptocurrency asset slug

## Facts

- Endpoint: GET https://rest.coincap.io/v3/agentFriendly/ta/%7Bslug%7D/rsi
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/coincap-rsi-relative-strength-index-endpoint-c84673ab
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_nvv1AeMEHN8wt_w8FKyec

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 coincap-rsi-relative-strength-index-endpoint-c84673ab
```

Example prompt: What's the current RSI for Bitcoin on CoinCap — is it showing overbought or oversold conditions right now?

## When to prefer this

Choose this endpoint when you need RSI specifically for cryptocurrency assets and want a per-call pay-as-you-go model via x402 USDC micropayments on Base (no API key signup required). Prefer this over general crypto data endpoints when you specifically need momentum/oscillator technical indicators rather than raw price data. Prefer over alternatives when building autonomous agent workflows where signing up for API keys is impractical.

## Known failure modes

- Invalid or unrecognized asset slug returns an error or empty result
- Payment failure via x402 protocol if USDC balance is insufficient
- Rate limiting if too many requests are made without valid API key or payment
- Network timeout for slow response from upstream market data feeds
- Asset slug not found if the coin is delisted or not tracked by CoinCap

## How this service works

CoinCap gives AI agents, apps, and developers real-time cryptocurrency market data.

Two ways to access:
- **API key** — sign up at https://coincap.io and pass `Authorization: Bearer <key>` or `?apiKey=<key>`.
- **Keyless x402** (agents) — the 10 `agentFriendly` endpoints accept per-call USDC payment on Base via the [x402 protocol](https://x402.gitbook.io/x402). No signup needed. See `/.well-known/x402.json` for the machine-readable payment catalog.

## Output

Returns RSI technical indicator data for the specified cryptocurrency asset, including the RSI value (typically 0–100) that indicates whether the asset is overbought (above 70), oversold (below 30), or neutral, along with any associated metadata such as the time period used for calculation.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "slug"
 ],
 "properties": {
  "slug": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "object"
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/coincap-rsi-relative-strength-index-endpoint-c84673ab/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from rest.coincap.io](https://www.zero.xyz/host/rest.coincap.io/llms.txt)