diff --git a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/FinTsClientCallback.kt b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/FinTsClientCallback.kt
index 195fb8f0..2b2f8638 100644
--- a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/FinTsClientCallback.kt
+++ b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/FinTsClientCallback.kt
@@ -27,4 +27,11 @@ interface FinTsClientCallback {
      */
     suspend fun enterTanGeneratorAtc(bank: BankData, tanMedium: TanGeneratorTanMedium): EnterTanGeneratorAtcResult
 
+    /**
+     * Gets fired when a FinTS message get sent to bank server, a FinTS message is received from bank server or an error occurred.
+     *
+     * Be aware, in order that this message gets fired [net.dankito.banking.fints.config.FinTsClientOptions.fireCallbackOnMessageLogs] has to be set to true.
+     */
+    fun messageLogAdded(messageLogEntry: MessageLogEntry)
+
 }
\ No newline at end of file
diff --git a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/NoOpFinTsClientCallback.kt b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/NoOpFinTsClientCallback.kt
index a1bb118a..a7506e83 100644
--- a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/NoOpFinTsClientCallback.kt
+++ b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/NoOpFinTsClientCallback.kt
@@ -18,4 +18,8 @@ open class NoOpFinTsClientCallback : FinTsClientCallback {
         return EnterTanGeneratorAtcResult.userDidNotEnterAtc()
     }
 
+    override fun messageLogAdded(messageLogEntry: MessageLogEntry) {
+
+    }
+
 }
\ No newline at end of file
diff --git a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/SimpleFinTsClientCallback.kt b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/SimpleFinTsClientCallback.kt
index 9b90695d..66b52f4b 100644
--- a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/SimpleFinTsClientCallback.kt
+++ b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/callback/SimpleFinTsClientCallback.kt
@@ -5,14 +5,15 @@ import net.dankito.banking.fints.model.*
 
 
 open class SimpleFinTsClientCallback(
-    protected open val enterTan: ((tanChallenge: TanChallenge) -> Unit)? = null,
+    protected open val askUserForTanMethod: ((supportedTanMethods: List<TanMethod>, suggestedTanMethod: TanMethod?) -> TanMethod?)? = null,
+    protected open val messageLogAdded: ((MessageLogEntry) -> Unit)? = null,
     protected open val enterTanGeneratorAtc: ((bank: BankData, tanMedium: TanGeneratorTanMedium) -> EnterTanGeneratorAtcResult)? = null,
-    protected open val askUserForTanMethod: ((supportedTanMethods: List<TanMethod>, suggestedTanMethod: TanMethod?) -> TanMethod?)? = null
+    protected open val enterTan: ((tanChallenge: TanChallenge) -> Unit)? = null
 ) : FinTsClientCallback {
 
-    constructor() : this(null) // Swift does not support default parameter values -> create constructor overloads
+    constructor() : this(null as ((tanChallenge: TanChallenge) -> Unit)?) // Swift does not support default parameter values -> create constructor overloads
 
-    constructor(enterTan: ((tanChallenge: TanChallenge) -> Unit)?) : this(enterTan, null)
+    constructor(enterTan: ((tanChallenge: TanChallenge) -> Unit)?) : this(null, null, null, enterTan)
 
 
     override suspend fun askUserForTanMethod(supportedTanMethods: List<TanMethod>, suggestedTanMethod: TanMethod?): TanMethod? {
@@ -28,4 +29,8 @@ open class SimpleFinTsClientCallback(
         return enterTanGeneratorAtc?.invoke(bank, tanMedium) ?: EnterTanGeneratorAtcResult.userDidNotEnterAtc()
     }
 
+    override fun messageLogAdded(messageLogEntry: MessageLogEntry) {
+        messageLogAdded?.invoke(messageLogEntry)
+    }
+
 }
\ No newline at end of file
diff --git a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/config/FinTsClientOptions.kt b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/config/FinTsClientOptions.kt
index cab7bfa6..b37330a1 100644
--- a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/config/FinTsClientOptions.kt
+++ b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/config/FinTsClientOptions.kt
@@ -3,6 +3,19 @@ package net.dankito.banking.fints.config
 import net.dankito.banking.fints.model.ProductData
 
 data class FinTsClientOptions(
+    /**
+     * If set to true then [net.dankito.banking.fints.callback.FinTsClientCallback.messageLogAdded] get fired when a
+     * FinTS message get sent to bank server, a FinTS message is received from bank server or an error occurred.
+     *
+     * Defaults to false.
+     */
+    val fireCallbackOnMessageLogs: Boolean = false,
+
+    /**
+     * If sensitive data like user name, password, login name should be removed from FinTS messages before being logged.
+     *
+     * Defaults to true.
+     */
     val removeSensitiveDataFromMessageLog: Boolean = true,
     val version: String = "1.0.0", // TODO: get version dynamically
     val productName: String = "15E53C26816138699C7B6A3E8"
diff --git a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/log/MessageLogCollector.kt b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/log/MessageLogCollector.kt
index f955438b..e91f5de2 100644
--- a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/log/MessageLogCollector.kt
+++ b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/log/MessageLogCollector.kt
@@ -2,6 +2,7 @@ package net.dankito.banking.fints.log
 
 import net.codinux.log.LoggerFactory
 import net.codinux.log.logger
+import net.dankito.banking.fints.callback.FinTsClientCallback
 import net.dankito.banking.fints.config.FinTsClientOptions
 import net.dankito.banking.fints.model.BankData
 import net.dankito.banking.fints.model.MessageLogEntry
@@ -14,6 +15,7 @@ import kotlin.reflect.KClass
 
 
 open class MessageLogCollector(
+    private val callback: FinTsClientCallback,
     private val options: FinTsClientOptions = FinTsClientOptions(),
     private val finTsUtils: FinTsUtils = FinTsUtils()
 ) {
@@ -55,9 +57,9 @@ open class MessageLogCollector(
     open fun addMessageLog(type: MessageLogEntryType, message: String, context: MessageContext) {
         val messageTrace = createMessageTraceString(type, context)
 
-        addMessageLogEntry(type, context, messageTrace, message)
-
         log.debug { "$messageTrace\n${prettyPrintFinTsMessage(message)}" }
+
+        addMessageLogEntry(type, context, messageTrace, message)
     }
 
     open fun logError(loggingClass: KClass<*>, message: String, context: MessageContext, e: Exception? = null) {
@@ -70,7 +72,14 @@ open class MessageLogCollector(
     }
 
     protected open fun addMessageLogEntry(type: MessageLogEntryType, context: MessageContext, messageTrace: String, message: String, error: Throwable? = null) {
-        _messageLog.add(MessageLogEntry(type, context, messageTrace, message, error))
+        val newEntry = MessageLogEntry(type, context, messageTrace, message, error)
+
+        _messageLog.add(newEntry)
+
+        if (options.fireCallbackOnMessageLogs) {
+            // TODO: pretty print message
+            callback.messageLogAdded(newEntry)
+        }
     }
 
 
diff --git a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/model/JobContext.kt b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/model/JobContext.kt
index 694943dc..213f9682 100644
--- a/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/model/JobContext.kt
+++ b/fints4k/src/commonMain/kotlin/net/dankito/banking/fints/model/JobContext.kt
@@ -24,7 +24,7 @@ open class JobContext(
      * Only set if the current context is for a specific account (like get account's transactions).
      */
     open val account: AccountData? = null,
-    protected open val messageLogCollector: MessageLogCollector = MessageLogCollector(config.options)
+    protected open val messageLogCollector: MessageLogCollector = MessageLogCollector(callback, config.options)
 ) : MessageBaseData(bank, config.options.product), IMessageLogAppender {
 
     companion object {