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CoinCap Market Cap History
x402
CoinCap Market Cap History is a paid API for AI agents from rest.coincap.io, paid per call via x402, $0.01/call, status unknown (last checked 2026-09-13).
Returns historical market capitalization data for a specific cryptocurrency asset by slug
Price / call$0.01
Success—
StatusUnknown
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 a time-series dataset of market capitalization values for the specified cryptocurrency, including historical data points with timestamps and corresponding market cap figures in USD, allowing trend analysis over time.
Example use cases
Crypto market cap trend research
“Show me the full historical market cap series for ethereum so I can see how it grew from early days to now.”
Portfolio valuation context
“Pull the market cap history for solana from CoinCap — I want to understand its market size trajectory before deciding on my position.”
Comparative market analysis
“Get me the historical market cap data for cardano using its slug 'cardano' so I can compare it against other layer-1 blockchains.”
Technical details
Endpoint
GEThttps://rest.coincap.io/v3/agentFriendly/asset_mcap_history/%7Bslug%7DWhen to prefer
Use this endpoint when you need historical market capitalization data for a specific cryptocurrency identified by its CoinCap slug. Prefer this over price history endpoints when the analysis specifically concerns market cap (circulating supply × price) rather than raw price. It is ideal for trend analysis, valuation context, or comparing a coin's growth trajectory over time. The x402 per-call payment model makes it accessible without API key registration for one-off agent queries.
Side effects
- Invalid or misspelled asset slug returns a 404 or empty dataset
- Unknown slug not in CoinCap database returns an error
- Missing or invalid API key / failed x402 payment returns 401 or 402
- Rate limiting may occur if too many requests are made in quick succession
- Network timeouts for slow connections
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| slugrequired | string |
Output
Schema · Response
{
"type": "object"
}Tags
x402
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