diff --git a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairApi.kt b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairApi.kt
index f8098293..ec36fc0c 100644
--- a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairApi.kt
+++ b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/apisync/blockchair/BlockchairApi.kt
@@ -1,5 +1,7 @@
 package io.horizontalsystems.bitcoincore.apisync.blockchair
 
+import com.eclipsesource.json.Json
+import com.eclipsesource.json.JsonObject
 import io.horizontalsystems.bitcoincore.apisync.model.AddressItem
 import io.horizontalsystems.bitcoincore.apisync.model.BlockHeaderItem
 import io.horizontalsystems.bitcoincore.apisync.model.TransactionItem
@@ -77,7 +79,14 @@ class BlockchairApi(
     }
 
     fun broadcastTransaction(rawTransactionHex: String) {
-        apiManager.post("$chainId/push/transaction", "{ \"data\" : \"$rawTransactionHex\"}")
+        val apiManager = ApiManager("https://api.blockchair.com")
+        val url = "$chainId/push/transaction"
+
+        val body = JsonObject().apply {
+            this["data"] = Json.value(rawTransactionHex)
+        }.toString()
+
+        apiManager.post(url, body)
     }
 
     private fun fetchTransactions(
@@ -129,7 +138,7 @@ class BlockchairApi(
 
     private fun dateStringToTimestamp(date: String): Long? {
         return try {
-            dateFormat.parse(date)?.time?.let {  it / 1000 }
+            dateFormat.parse(date)?.time?.let { it / 1000 }
         } catch (e: ParseException) {
             null
         }
diff --git a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/managers/ApiManager.kt b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/managers/ApiManager.kt
index 602bdc10..47789c6a 100644
--- a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/managers/ApiManager.kt
+++ b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/managers/ApiManager.kt
@@ -1,10 +1,11 @@
 package io.horizontalsystems.bitcoincore.managers
 
-import android.util.Log
 import com.eclipsesource.json.Json
 import com.eclipsesource.json.JsonValue
+import okhttp3.MediaType.Companion.toMediaTypeOrNull
 import okhttp3.OkHttpClient
 import okhttp3.Request
+import okhttp3.RequestBody.Companion.toRequestBody
 import java.io.BufferedOutputStream
 import java.io.BufferedWriter
 import java.io.IOException
@@ -31,6 +32,7 @@ class ApiManager(private val host: String) {
                         connectTimeout = 5000
                         readTimeout = 60000
                         setRequestProperty("Accept", "application/json")
+                        setRequestProperty("content-type", "application/json")
                     }.getInputStream()
         } catch (exception: IOException) {
             throw ApiManagerException.Other("${exception.javaClass.simpleName}: $host")
@@ -42,14 +44,12 @@ class ApiManager(private val host: String) {
         try {
             val path = "$host/$resource"
 
-            Log.e("e", "path: $path")
-            Log.e("e", "body: $data")
-
             logger.info("Fetching $path")
 
             val url = URL(path)
             val urlConnection = url.openConnection() as HttpURLConnection
             urlConnection.requestMethod = "POST"
+            urlConnection.setRequestProperty("Content-Type", "application/json")
             val out = BufferedOutputStream(urlConnection.outputStream)
             val writer = BufferedWriter(OutputStreamWriter(out, "UTF-8"))
             writer.write(data)
@@ -99,6 +99,7 @@ class ApiManager(private val host: String) {
             throw ApiManagerException.Other("${e.javaClass.simpleName}: $host, ${e.localizedMessage}")
         }
     }
+
 }
 
 sealed class ApiManagerException : Exception() {
diff --git a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/transactions/TransactionSender.kt b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/transactions/TransactionSender.kt
index 7f532304..53a5de4d 100644
--- a/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/transactions/TransactionSender.kt
+++ b/bitcoincore/src/main/kotlin/io/horizontalsystems/bitcoincore/transactions/TransactionSender.kt
@@ -1,6 +1,5 @@
 package io.horizontalsystems.bitcoincore.transactions
 
-import android.util.Log
 import io.horizontalsystems.bitcoincore.BitcoinCore
 import io.horizontalsystems.bitcoincore.apisync.blockchair.BlockchairApi
 import io.horizontalsystems.bitcoincore.core.IInitialDownload
@@ -102,16 +101,14 @@ class TransactionSender(
     }
 
     private fun sendViaAPI(transactions: List<FullTransaction>, blockchairApi: BlockchairApi) {
-        timer.startIfNotRunning()
-
         transactions.forEach { transaction ->
             try {
-                transactionSendStart(transaction)
-
                 val hex = transactionSerializer.serialize(transaction).toHexString()
                 blockchairApi.broadcastTransaction(hex)
+
+                transactionSyncer.handleRelayed(listOf(transaction))
             } catch (error: Throwable) {
-                Log.e("e", "API send error", error)
+                transactionSyncer.handleInvalid(transaction)
             }
         }
     }
@@ -172,6 +169,7 @@ class TransactionSender(
                 transactionSendSuccess(task.transaction)
                 true
             }
+
             else -> false
         }
     }