I am trying RPC request to bitcoind node,using Kotlin. My code looks like

import khttp.delete as httpDelete
val node_url = "http://rpcusr:[email protected]:18443"
val json_resp =  khttp.post(url = node_url,
                            headers = mapOf("Content-Type" to "application/json"),  //also tried application.json and text/plain
                            json = mapOf("id" to "curltext","jsonrpc" to 1,"method" to "getblockchaininfo","params" to arrayOf("")))

and its output -->

<META HTTP-EQUIV='Content-Type' CONTENT='text/html; charset=ISO-8859-1'>
<BODY><H1>401 Unauthorized.</H1></BODY>

bitcoin.conf -->


Using curl i am getting desired output

CURL command-->

curl -v --data-binary '{"jsonrpc": "1.0", "id":"curltest", "method": "getblockchaininfo", "params": [] }' -H 'content-type: text/plain;' http://abc:[email protected]:18443

o/p -->


The reason why i am asking this question on this forum is, i took the same approach to get rpc response from Ethereum node and i am getting proper response,the error is occuring only with bitcoin & litecoin node

Any clue why it is behaving this way ?

  • mapOf("Contenet-Type" to "application.json"),. Try changing that to Content-Type. If it still doesn't work, try application/json as well. Commented Jun 19, 2018 at 20:08
  • didnt work with any of the combination . Response is same in all cases Commented Jun 19, 2018 at 20:53
  • Can you post the relevant bitcoind debug.log output? That may have some clues
    – chytrik
    Commented Jun 20, 2018 at 20:31
  • debug.log only shows blocks being downloaded and nothing relevant Commented Jun 21, 2018 at 7:16

2 Answers 2


You are not properly sending the authentication headers. From a quick reading of the documentation, you need to add auth=BasicAuthorization("rpcuser", "rpcpass") to your post request because the URL http://rpcusr:[email protected]:18443" is not sufficient for khttp to send the basic authentication headers.


We need to pass Authorization method as :

val jsonstring = khttp.post(
        url = node_url,
        headers = mapOf("Authorization" to computeBasicAuth("abc","pass")),
        data = JSONObject("{\"jsonrpc\": \"1.0\", \"id\":\"curltest\", \"method\": \"getrawmempool\", \"params\": [] }")


fun computeBasicAuth(user: String, password: String) ="Basic ${BASE64.encodeToString("$user:$password".toByteArray())}"

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