Blockchain API

Broadcast Transactions

Send a transaction you signed yourself. Post the signed raw transaction to one endpoint on any of 18 blockchains, and Crypto APIs pushes it to the network.

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You sign, we send One endpoint for every chain Optional callback URL

What you can build

Broadcasting for wallets, exchanges and payouts

Keep your keys in-house

Sign on your own servers or hardware, then hand only the signed transaction to the API. Your private keys stay with you.

Skip running nodes

Reach 18 blockchains without operating, syncing or watching a node for each.

Hear back

Add a callback URL and a secret to the request, and Crypto APIs calls your URL about the transaction.

Quick start

Make your first Broadcast Transactions call

Real paths and example responses from the API reference. Add your API key and run it.

Base URL https://rest.cryptoapis.io
Auth: the X-API-Key header
JSON responses, same shape on every chain

curl -X POST https://rest.cryptoapis.io/broadcast-transactions/ethereum/mainnet \
  -H "Content-Type: application/json" \
  -H "X-API-Key: YOUR_API_KEY" \
  -d '{
  "data": {
    "item": {
      "callbackSecretKey": "yourSecretString",
      "callbackUrl": "https://example.com",
      "signedTransactionHex": "0xf86a22827d00831e8480941b85a43e2e7f52e7…"
    }
  }
}'

200 OKExample response, excerpt

{
  "transactionId": "347d96855d41b77f1e23048fff11c18e9fe699ee69b0b402338f34189734e0a2"
}

Endpoints

Every Broadcast Transactions endpoint

Each operation links to its page in the API reference, with its parameters and responses. Paths take the blockchain and the network, so moving to another chain is a change of path.

API reference

What it does

Method and path

Blockchains

Reference

Broadcast Locally Signed Transaction

POST/broadcast-transactions/{blockchain}/{network}

18 blockchains

Docs

Blockchains

Broadcast Transactions works on 18 blockchains

Mainnets, and test networks where the chain has one. Open a chain for its own endpoints and quick start.

See all networks

Bitcoin

Ethereum

XRP Ledger

Ethereum Classic

Bitcoin Cash

Dash

Litecoin

Dogecoin

Zcash

BNB Smart Chain

Polygon

Tron

Solana

Tezos

Avalanche

Arbitrum

Optimism

Base

Pairs well with

Build the rest of the flow

All Blockchain API features

Prepare TransactionsUnsigned transactions, ready to sign on your server Offline SignerSign on your own server, free and open source Blockchain EventsWebhooks when a transaction confirms or a block is mined

FAQ

Broadcast Transactions questions

Which blockchains does Broadcast Transactions support?

Broadcast Transactions works on 18 blockchains: Bitcoin, Ethereum, XRP Ledger, Ethereum Classic, Bitcoin Cash, Dash, Litecoin, Dogecoin, Zcash, BNB Smart Chain, Polygon, Tron, Solana, Tezos, Avalanche, Arbitrum, Optimism, Base. Each chain's page lists its networks and its own endpoints.

Can I try Broadcast Transactions for free?

Yes, for 14 days. The Blockchain API free trial includes Broadcast Transactions and every other feature, with no card. It ends after 14 days or when its credits run out; after that, calls need a subscription, listed on the pricing page.

What is the CryptoAPIs Broadcast Transactions API and how does it work?

It lets you push a transaction you have already signed locally to the blockchain network through a single specialized endpoint. You keep your private keys on your side, sign the raw transaction offline, and CryptoAPIs relays the signed payload to a node for you. This means CryptoAPIs never handles your keys while still giving you node access for broadcasting.

Does the Broadcast Transactions API support Solana and Bitcoin?

Yes. Solana is supported for broadcasting locally signed transactions, as are Bitcoin and the other UTXO chains (Bitcoin Cash, Litecoin, Dogecoin, Dash, Zcash). XRP and Kaspa are also covered, alongside the EVM chains.

Can I broadcast transactions on testnets as well as mainnet?

Yes. Broadcasting works on both mainnets and testnets across the networks CryptoAPIs supports. For example EVM chains offer testnets such as Sepolia, Amoy, Fuji, Nile and Mordor, and UTXO chains such as Bitcoin, Litecoin and Dogecoin offer their standard testnets. Kaspa is currently mainnet only.

Does broadcasting a transaction with CryptoAPIs mean they hold my private keys?

No. The model is non-custodial for signing: you sign the transaction locally with your own keys and only send the already-signed transaction to the broadcast endpoint. CryptoAPIs relays that signed payload to a node and never sees or stores your private keys.

Start building with Broadcast Transactions

14-day free trial, mainnet included. No card needed.

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