We’re packing our bags and preparing to move...domains!

To make way for our new and exciting products coming this year, we’re saying hello to our new home. blockchain.info will soon be changing URLs as it's combined with our company site, blockchain.com.

Read more about what to expect.

Our WebSocket API allows developers to receive Real-Time notifications about new transactions and blocks. The Websocket echo test can be useful for debugging.

Connection URL:


Once the socket is open you can subscribe to a channel by sending an "op" message.



Subscribing to Unconfirmed transactions

Subscribe to notifications for all new bitcoin transactions.




Subscribing to an Address

Receive new transactions for a specific bitcoin address:

{"op":"addr_sub", "addr":"$bitcoin_address"}


{"op":"addr_unsub", "addr":"$bitcoin_address"}

Message on new transaction:

    "op": "utx",
    "x": {
        "lock_time": 0,
        "ver": 1,
        "size": 192,
        "inputs": [
                "sequence": 4294967295,
                "prev_out": {
                    "spent": true,
                    "tx_index": 99005468,
                    "type": 0,
                    "addr": "1BwGf3z7n2fHk6NoVJNkV32qwyAYsMhkWf",
                    "value": 65574000,
                    "n": 0,
                    "script": "76a91477f4c9ee75e449a74c21a4decfb50519cbc245b388ac"
                "script": "483045022100e4ff962c292705f051c2c2fc519fa775a4d8955bce1a3e29884b2785277999ed02200b537ebd22a9f25fbbbcc9113c69c1389400703ef2017d80959ef0f1d685756c012102618e08e0c8fd4c5fe539184a30fe35a2f5fccf7ad62054cad29360d871f8187d"
        "time": 1440086763,
        "tx_index": 99006637,
        "vin_sz": 1,
        "hash": "0857b9de1884eec314ecf67c040a2657b8e083e1f95e31d0b5ba3d328841fc7f",
        "vout_sz": 1,
        "relayed_by": "",
        "out": [
                "spent": false,
                "tx_index": 99006637,
                "type": 0,
                "addr": "1A828tTnkVFJfSvLCqF42ohZ51ksS3jJgX",
                "value": 65564000,
                "n": 0,
                "script": "76a914640cfdf7b79d94d1c980133e3587bd6053f091f388ac"

Subscribing to new Blocks

Receive notifications when a new block is found. Note: if the chain splits you will receive more than one notification for a specific block height.




Message On New Block:

    "op": "block",
    "x": {
        "txIndexes": [
        "nTx": 0,
        "totalBTCSent": 0,
        "estimatedBTCSent": 0,
        "reward": 0,
        "size": 0,
        "blockIndex": 190460,
        "prevBlockIndex": 190457,
        "height": 170359,
        "hash": "00000000000006436073c07dfa188a8fa54fefadf571fd774863cda1b884b90f",
        "mrklRoot": "94e51495e0e8a0c3b78dac1220b2f35ceda8799b0a20cfa68601ed28126cfcc2",
        "version": 1,
        "time": 1331301261,
        "bits": 436942092,
        "nonce": 758889471

Debugging OPs:


Responds with the latest block


Responds with the latest transaction. If subscribed to any addresses it will respond with the latest transaction involving those addresses.