Introduction

The following guide aims to provide examples to help you start building Bitcoin-based applications. To make the best use of this document, you may want to install the current version of Bitcoin Core, either from source or from a pre-compiled executable.

Once installed, you’ll have access to three programs: bitcoind, bitcoin-qt, and bitcoin-cli.

• bitcoin-qt provides a combination full Bitcoin Peer and Wallet frontend. From the Help menu, you can access a console where you can enter the RPC commands used throughout this document.
• bitcoind is more useful for programming: it provides a full Peer which you can interact with through RPCs to port 8332 (or 18332 for Testnet).
• bitcoin-cli allows you to send RPC commands to bitcoind from the command line. For example, bitcoin-cli help

All three programs get settings from bitcoin.conf in the Bitcoin application directory:

• Windows: %APPDATA%\Bitcoin\
• OSX: $HOME/Library/Application Support/Bitcoin/
• Linux: $HOME/.bitcoin/

To use bitcoind and bitcoin-cli, you will need to add a RPC password to your bitcoin.conf file. Both programs will read from the same file if both run on the same system as the same user, so any long random password will work:

rpcpassword=change_this_to_a_long_random_password

You should also make the bitcoin.conf file only readable to its owner. On Linux, Mac OSX, and other Unix-like systems, this can be accomplished by running the following command in the Bitcoin application directory:

chmod 0600 bitcoin.conf

For development, it’s safer and cheaper to use Bitcoin’s test network (Testnet) or Regression test mode (Regtest) described below.

Questions about Bitcoin use are best sent to the BitcoinTalk forum and IRC channels. Errors or suggestions related to documentation on Bitcoin.org can be submitted as an issue or posted to the bitcoin-documentation mailing list.

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