API reference (JSON-RPC)

Controlling Bitcoin

Run bitcoind or bitcoin -server. You can control it via the command-line or by HTTP JSON-RPC commands.

You must create a bitcoin.conf configuration file setting an rpcuser and rpcpassword; see Running Bitcoin for details.

Now run:

 $ ./bitcoind
 bitcoin server starting
 $ ./bitcoind help
 # shows the help text

A list of RPC calls will be shown.

 $ ./bitcoind getbalance
 2000.00000

JSON-RPC

Running Bitcoin with the -server argument (or running bitcoind) tells it to function as a HTTP JSON-RPC server, but Basic access authentication must be used when communicating with it, and, for security, by default, the server only accepts connections from other processes on the same machine. If your HTTP or JSON library requires you to specify which 'realm' is authenticated, use 'jsonrpc'.

Bitcoin supports SSL (https) JSON-RPC connections beginning with version 0.3.14. See the rpcssl wiki page for setup instructions and a list of all bitcoin.conf configuration options.

To access the server you should find a suitable library for your language.

Proper money handling

See the proper money handling page for notes on avoiding rounding errors when handling bitcoin values.

Python

python-jsonrpc is the official JSON-RPC implementation for Python. It automatically generates Python methods for RPC calls. However, due to its design for supporting old versions of Python, it is also rather inefficient. jgarzik has forked it as Python-BitcoinRPC and optimized it for current versions. Generally, this version is recommended.

While BitcoinRPC lacks a few obscure features from jsonrpc, software using only the ServiceProxy class can be written the same to work with either version the user might choose to install:

  from jsonrpc import ServiceProxy
  
  access = ServiceProxy("http://user:password@127.0.0.1:8332")
  access.getinfo()
  access.listreceivedbyaddress(6)
  #access.sendtoaddress("11yEmxiMso2RsFVfBcCa616npBvGgxiBX", 10)

Ruby

=begin
Make sure to do:
    gem install rest-client

Usage:
    h = ServiceProxy.new('http://user:password@127.0.0.1:8332')
    puts h.getinfo.call
    puts h.getbalance.call 'accname'
=end
require 'json'
require 'rest_client'

class JSONRPCException < RuntimeError
    def initialize()
        super()
    end
end

class ServiceProxy
    def initialize(service_url, service_name=nil)
        @service_url = service_url
        @service_name = service_name
    end

    def method_missing(name, *args, &block)
        if @service_name != nil
            name = "%s.%s" % [@service_name, name]
        end
        return ServiceProxy.new(@service_url, name)
    end

    def respond_to?(sym)
    end

    def call(*args)
        postdata = {"method" => @service_name, "params" => args, "id" => "jsonrpc"}.to_json
        respdata = RestClient.post @service_url, postdata
        resp = JSON.parse respdata
        if resp["error"] != nil
            raise JSONRPCException.new, resp['error']
        end
        return resp['result']
    end
end

PHP

The JSON-RPC PHP library also makes it very easy to connect to Bitcoin. For example:

  require_once 'jsonRPCClient.php';
  
  $bitcoin = new jsonRPCClient('http://user:password@127.0.0.1:8332/');
   
  echo "<pre>\n";
  print_r($bitcoin->getinfo()); echo "\n";
  echo "Received: ".$bitcoin->getreceivedbylabel("Your Address")."\n";
  echo "</pre>";

Java

The easiest way to tell Java to use HTTP Basic authentication is to set a default Authenticator:

  final String rpcuser ="...";
  final String rpcpassword ="...";
  
  Authenticator.setDefault(new Authenticator() {
      protected PasswordAuthentication getPasswordAuthentication() {
          return new PasswordAuthentication (rpcuser, rpcpassword.toCharArray());
      }
  });

Once that is done, any JSON-RPC library for Java (or ordinary URL POSTs) may be used to communicate with the Bitcoin server.

Perl

The JSON::RPC package from CPAN can be used to communicate with Bitcoin. You must set the client's credentials; for example:

  use JSON::RPC::Client;
  use Data::Dumper;
   
  my $client = new JSON::RPC::Client;
  
  $client->ua->credentials(
     'localhost:8332', 'jsonrpc', 'user' => 'password'  # REPLACE WITH YOUR bitcoin.conf rpcuser/rpcpassword
      );
  
  my $uri = 'http://localhost:8332/';
  my $obj = {
      method  => 'getinfo',
      params  => [],
   };
   
  my $res = $client->call( $uri, $obj );
   
  if ($res){
      if ($res->is_error) { print "Error : ", $res->error_message; }
      else { print Dumper($res->result); }
  } else {
      print $client->status_line;
  }

.NET (C#)

The communication with rpc service can be achieved using the standard httprequest/response objects. A library for serialising and deserialising Json will make your life a lot easier:

• JayRock for .NET 4.0
• Json.Net for .NET 2.0 and above

The following example uses Json.Net:

 HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create("http://localhost.:8332");
 webRequest.Credentials = new NetworkCredential("user", "pwd");
 /// important, otherwise the service can't desirialse your request properly
 webRequest.ContentType = "application/json-rpc";
 webRequest.Method = "POST";
  
 JObject joe = new JObject();
 joe.Add(new JProperty("jsonrpc", "1.0"));
 joe.Add(new JProperty("id", "1"));
 joe.Add(new JProperty("method", Method));
 // params is a collection values which the method requires..
 if (Params.Keys.Count == 0)
 {
  joe.Add(new JProperty("params", new JArray()));
 }
 else
 {
     JArray props = new JArray();
     // add the props in the reverse order!
     for (int i = Params.Keys.Count - 1; i >= 0; i--)
     {
        .... // add the params
     }
     joe.Add(new JProperty("params", props));
     }
  
     // serialize json for the request
     string s = JsonConvert.SerializeObject(joe);
     byte[] byteArray = Encoding.UTF8.GetBytes(s);
     webRequest.ContentLength = byteArray.Length;
     Stream dataStream = webRequest.GetRequestStream();
     dataStream.Write(byteArray, 0, byteArray.Length);
     dataStream.Close();
     
     
     WebResponse webResponse = webRequest.GetResponse();
     
     ... // deserialze the response

There is also a wrapper for Json.NET called Bitnet (https://sourceforge.net/projects/bitnet) implementing Bitcoin API in more convenient way:

     BitnetClient bc = new BitnetClient("http://127.0.0.1:8332");
     bc.Credentials = new NetworkCredential("user", "pass");

     var p = bc.GetDifficulty();
     Console.WriteLine("Difficulty:" + p.ToString());

     var inf = bc.GetInfo();
     Console.WriteLine("Balance:" + inf["balance"]);

Node.js

There are two unofficial node.js modules for interacting with the bitcoin client.

• node-bitcoin (npm: bitcoin)
• Kapitalize (npm: kapitalize)

Example using node-bitcoin:

var bitcoin = require('bitcoin');
var client = new bitcoin.Client({
  host: 'localhost',
  port: 8332,
  user: 'user',
  pass: 'pass'
});

client.getDifficulty(function(err, difficulty) {
  if (err) {
    console.log('Error...');
    console.log(err);
    return;
  }

  console.log('Difficulty: ' + difficulty);
});

Example using Kapitalize:

var client = require('kapitalize')()

client.auth('user', 'password')

client
.getInfo()
.getDifficulty(function(err, difficulty) {
  console.log('Dificulty: ', difficulty)
})

Command line (cURL)

You can also send commands and see results using cURL or some other command-line HTTP-fetching utility; for example:

  curl --user user --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "getinfo", "params": [] }' 
    -H 'content-type: text/plain;' http://127.0.0.1:8332/

You will be prompted for your rpcpassword, and then will see something like:

  {"result":{"balance":0.000000000000000,"blocks":59952,"connections":48,"proxy":"","generate":false,
     "genproclimit":-1,"difficulty":16.61907875185736,"error":null,"id":"curltest"}

See Also

• API calls list
• Running Bitcoin
• Lazy API
• PHP developer intro
• Raw Transactions API