My search for a list of public Bitcoin feerate estimation APIs ended without any real results. Jameson Lopp has a section on feerate estimators on his bitcoin.page and Antoine Le Calvez’s dashboard txstats.com provides a visualization of different estimation APIs. But that is not what I was looking for. That’s why I compiled this list.

I opted to only include publicly advertised feerate estimation APIs by e.g. payment processors and block explorers. I’m purposefully leaving out list APIs by wallets, such as Mycelium and Trezor because their APIs are not publicly advertised. Additionally, I’m leaving out Bitcoin Core’s feerate estimates via the estimatesmartfee RPC. I don’t consider the RPC publicly reachable as in reachable over the web by everyone (some services wrap the estimatesmartfee RPC however).

The following list of public feerate APIs is lexicographically sorted.

bitcoiner.live API

The bitcoiner.live API provides sat/vByte estimates for confirmation in half an hour, 1 hour, 2 hours, 3 hours, 6 hours, 12 hours and 24 hours. It’s reachable under https://bitcoiner.live/api/fees/estimates/latest.

{
  "timestamp": 1563456789,
  "estimates": {
    "30": {
      "sat_per_vbyte": 12.0,
      [ ... ]
    },
    "60": {
      "sat_per_vbyte": 12.0,
      [ ... ]
    },
    "120": {
      "sat_per_vbyte": 8.0,
      [ ... ]
    },
    [ ... ]
  }
}

BitGo API

Bitgo’s feerate API is reachable under https://www.bitgo.com/api/v2/btc/tx/fee and there is documentation available here. The API returns estimates for different block targets in sat/kB. (sat/kB / 1000 = sat/Byte)

{
  "feePerKb": 61834,
  "cpfpFeePerKb": 61834,
  "numBlocks": 2,
  "confidence": 80,
  "multiplier": 1,
  "feeByBlockTarget": {
    "1": 64246,
    "2": 61834,
    "3": 56258,
    [ ... ]
  }
}

Bitpay Insight API

The API of Bitpay’s Insight instance is available under https://insight.bitpay.com/api/utils/estimatefee?nbBlocks=2,4,6. With the parameter nbBlocks the confirmation target in the next n blocks can be specified. Feerates are in BTC/kB. (BTC/kB x 100000 = sat/Byte)

{
  "2": 0.00051894,
  "4": 0.00047501,
  "6": 0.00043338
}

Blockchain.info API

Blockchain.info recommends sat/Byte feerates via https://api.blockchain.info/mempool/fees. They provide a regular and a priority feerate. Additionally a minimum and maximum feerate are included.

{
  "limits": {
    "min": 2,
    "max": 79
  },
  "regular": 4,
  "priority": 53
}

Blockchair API

The Blockchair API offers a transaction fee suggestion in sat/Byte via https://api.blockchair.com/bitcoin/stats. While their API is publicly available for occasional requests, they require an API key for more and periodical requests. You can read more about the API here.

{
  "data": {
    [ ... ]
    "suggested_transaction_fee_per_byte_sat": 1
  },
  [ ... ]
}

BlockCypher API

The BlockCypher API includes a low, medium and high feerate estimate in https://api.blockcypher.com/v1/btc/main. The feerates are in sat/kB. (sat/kB / 1000 = sat/Byte)

{
  [ ... ]
  "high_fee_per_kb": 41770,
  "medium_fee_per_kb": 25000,
  "low_fee_per_kb": 15000,
  [ ... ]
}

Blockstream.info API

Blockstream.info offers an API returning feerates for different confirmation targets in sat/vByte under https://blockstream.info/api/fee-estimates. The API is documented here.

{
  "2": 32.749,
  "3": 32.749,
  "4": 24.457,
  "6": 20.098,
  "10": 18.17,
  "20": 10.113,
  "144": 1,
  "504": 1,
  "1008": 1
}

BTC.com API

BTC.com offers a feerate estimate for the next block in sat/Byte under https://btc.com/service/fees/distribution.

{
  "tx_size": [ ... ],
  "tx_size_count": [ ... ],
  "tx_size_divide_max_size": [ ... ],
  "tx_duration_time_rate": [ ... ],
  "fees_recommended": {
    "one_block_fee": 14
  },
  "update_time": "1563456789"
}

earn.com API

The API behind bitcoinfees.earn.com is reachable under https://bitcoinfees.earn.com/api/v1/fees/recommended. Feerate estimates for the fastest confirmation, a confirmation in half an hour and a hour are shown in sat/Byte.

{
  "fastestFee": 44,
  "halfHourFee": 44,
  "hourFee": 4
}

Please let me know if you know a feerate estimation API I should add to the list.