MarginPad
Crypto futures prices, candles, funding, open interest, long/short and liquidations, 9 exchanges
Bitcoin API Service focusing on the transaction fee.
Mempool API is a free Cryptocurrency API that requires no API key, is served over HTTPS and does not support CORS, so it should be called from a server.

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Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Crypto futures prices, candles, funding, open interest, long/short and liquidations, 9 exchanges
Yes. The Mempool API is listed in the Cryptocurrency category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
No. The Mempool API requires no authentication, so you can start making requests without signing up.
Not directly. The Mempool API does not allow CORS, so call it from a server, serverless function or proxy instead of front-end JavaScript.
Yes. The Mempool API is served over HTTPS, so it's safe to use in production.