diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
index f7a03145..c8ff3936 100644
--- a/.idea/codeStyles/Project.xml
+++ b/.idea/codeStyles/Project.xml
@@ -1,6 +1,7 @@
 <component name="ProjectCodeStyleConfiguration">
   <code_scheme name="Project" version="173">
     <JetCodeStyleSettings>
+      <option name="NAME_COUNT_TO_USE_STAR_IMPORT" value="2147483647" />
       <option name="ALLOW_TRAILING_COMMA" value="true" />
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
     </JetCodeStyleSettings>
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/config/Config.kt b/app/src/main/java/pl/szczodrzynski/edziennik/config/Config.kt
index 4da4180e..fffa77a8 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/config/Config.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/config/Config.kt
@@ -39,6 +39,7 @@ class Config(db: AppDb) : BaseConfig(db) {
 
     var apiAvailabilityCheck by config<Boolean>(true)
     var apiInvalidCert by config<String?>(null)
+    var apiKeyCustom by config<String?>(null)
     var appInstalledTime by config<Long>(0L)
     var appRateSnackbarTime by config<Long>(0L)
     var appVersion by config<Int>(BuildConfig.VERSION_CODE)
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/interceptor/SignatureInterceptor.kt b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/interceptor/SignatureInterceptor.kt
index b766cea5..710bcb74 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/interceptor/SignatureInterceptor.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/data/api/szkolny/interceptor/SignatureInterceptor.kt
@@ -12,10 +12,11 @@ import pl.szczodrzynski.edziennik.ext.bodyToString
 import pl.szczodrzynski.edziennik.ext.currentTimeUnix
 import pl.szczodrzynski.edziennik.ext.hmacSHA1
 import pl.szczodrzynski.edziennik.ext.md5
+import pl.szczodrzynski.edziennik.ext.takeValue
 
 class SignatureInterceptor(val app: App) : Interceptor {
     companion object {
-        private const val API_KEY = "szkolny_android_42a66f0842fc7da4e37c66732acf705a"
+        const val API_KEY = "szkolny_android_42a66f0842fc7da4e37c66732acf705a"
     }
 
     override fun intercept(chain: Interceptor.Chain): Response {
@@ -27,7 +28,7 @@ class SignatureInterceptor(val app: App) : Interceptor {
 
         return chain.proceed(
                 request.newBuilder()
-                        .header("X-ApiKey", API_KEY)
+                        .header("X-ApiKey", app.config.apiKeyCustom?.takeValue() ?: API_KEY)
                         .header("X-AppVersion", BuildConfig.VERSION_CODE.toString())
                         .header("X-Timestamp", timestamp.toString())
                         .header("X-Signature", sign(timestamp, body, url))
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ext/MiscExtensions.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ext/MiscExtensions.kt
index 26dc442a..5ddb5dcb 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ext/MiscExtensions.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ext/MiscExtensions.kt
@@ -76,4 +76,6 @@ fun pendingIntentFlag(): Int {
 fun Int?.takeValue() = if (this == -1) null else this
 fun Int?.takePositive() = if (this == -1 || this == 0) null else this
 
+fun String?.takeValue() = if (this.isNullOrBlank()) null else this
+
 fun Any?.ignore() = Unit
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/ui/debug/LabPageFragment.kt b/app/src/main/java/pl/szczodrzynski/edziennik/ui/debug/LabPageFragment.kt
index ed3237ab..1c580968 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/ui/debug/LabPageFragment.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/ui/debug/LabPageFragment.kt
@@ -11,6 +11,7 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.view.isVisible
+import androidx.core.widget.doAfterTextChanged
 import androidx.sqlite.db.SimpleSQLiteQuery
 import com.chuckerteam.chucker.api.Chucker
 import com.chuckerteam.chucker.api.Chucker.SCREEN_HTTP
@@ -21,6 +22,7 @@ import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import pl.szczodrzynski.edziennik.*
 import pl.szczodrzynski.edziennik.config.Config
+import pl.szczodrzynski.edziennik.data.api.szkolny.interceptor.SignatureInterceptor
 import pl.szczodrzynski.edziennik.databinding.LabFragmentBinding
 import pl.szczodrzynski.edziennik.ext.*
 import pl.szczodrzynski.edziennik.ui.base.lazypager.LazyFragment
@@ -141,6 +143,16 @@ class LabPageFragment : LazyFragment(), CoroutineScope {
             app.config.apiInvalidCert = null
         }
 
+        b.apiKey.setText(app.config.apiKeyCustom ?: SignatureInterceptor.API_KEY)
+        b.apiKey.doAfterTextChanged {
+            it?.toString()?.let { key ->
+                if (key == SignatureInterceptor.API_KEY)
+                    app.config.apiKeyCustom = null
+                else
+                    app.config.apiKeyCustom = key.takeValue()?.trim()
+            }
+        }
+
         b.rebuildConfig.onClick {
             App.config = Config(App.db)
         }
diff --git a/app/src/main/res/layout/lab_fragment.xml b/app/src/main/res/layout/lab_fragment.xml
index 1b9ef55d..c1326fa3 100644
--- a/app/src/main/res/layout/lab_fragment.xml
+++ b/app/src/main/res/layout/lab_fragment.xml
@@ -133,6 +133,18 @@
                 android:text="Reset API signature"
                 android:textAllCaps="false" />
 
+            <com.google.android.material.textfield.TextInputLayout
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp">
+
+                <pl.szczodrzynski.edziennik.utils.TextInputKeyboardEdit
+                    android:id="@+id/apiKey"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:hint="API Key" />
+            </com.google.android.material.textfield.TextInputLayout>
+
             <Button
                 android:id="@+id/disableDebug"
                 android:layout_width="match_parent"