diff --git a/app/build.gradle b/app/build.gradle
index dc51efa..c33a24d 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -75,4 +75,5 @@ dependencies {
     implementation "androidx.work:work-runtime-ktx:2.3.2"
     implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.3'
     implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.2.0'
+    implementation 'org.greenrobot:eventbus:3.2.0'
 }
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 2f44e93..00fb347 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -79,6 +79,7 @@
         </activity>
 
         <service android:name=".services.SnoozeService"/>
+        <service android:name=".services.TimerService" />
 
         <receiver android:name=".receivers.AlarmReceiver"/>
 
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Context.kt b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Context.kt
index 2277ef3..009b2e1 100644
--- a/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Context.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Context.kt
@@ -226,13 +226,6 @@ fun Context.showAlarmNotification(alarm: Alarm) {
     scheduleNextAlarm(alarm, false)
 }
 
-fun Context.showTimerNotification(addDeleteIntent: Boolean) {
-    val pendingIntent = getOpenTimerTabIntent()
-    val notification = getTimerNotification(pendingIntent, addDeleteIntent)
-    val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
-    notificationManager.notify(TIMER_NOTIF_ID, notification)
-}
-
 @SuppressLint("NewApi")
 fun Context.getTimerNotification(pendingIntent: PendingIntent, addDeleteIntent: Boolean): Notification {
     var soundUri = config.timerSoundUri
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Int.kt b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Int.kt
new file mode 100644
index 0000000..56c7f19
--- /dev/null
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Int.kt
@@ -0,0 +1,6 @@
+package com.simplemobiletools.clock.extensions
+
+import java.util.concurrent.TimeUnit
+
+val Int.secondsToMillis get() = TimeUnit.SECONDS.toMillis(this.toLong())
+val Int.millisToSeconds get() = TimeUnit.MILLISECONDS.toSeconds(this.toLong())
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Long.kt b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Long.kt
index e4eac62..7500e53 100644
--- a/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Long.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/Long.kt
@@ -36,3 +36,6 @@ fun Long.timestampFormat(format: String = "dd. MM. yyyy"): String {
 
     return DateFormat.format(format, calendar).toString()
 }
+
+val Long.secondsToMillis get() = TimeUnit.SECONDS.toMillis(this)
+val Long.millisToSeconds get() = TimeUnit.MILLISECONDS.toSeconds(this)
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/extensions/gson/RuntimeTypeAdapterFactory.java b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/gson/RuntimeTypeAdapterFactory.java
new file mode 100644
index 0000000..b04dba4
--- /dev/null
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/gson/RuntimeTypeAdapterFactory.java
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2011 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.simplemobiletools.clock.extensions.gson;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+import com.google.gson.JsonPrimitive;
+import com.google.gson.TypeAdapter;
+import com.google.gson.TypeAdapterFactory;
+import com.google.gson.internal.Streams;
+import com.google.gson.reflect.TypeToken;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+
+import java.io.IOException;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * Adapts values whose runtime type may differ from their declaration type. This
+ * is necessary when a field's type is not the same type that GSON should create
+ * when deserializing that field. For example, consider these types:
+ * <pre>   {@code
+ *   abstract class Shape {
+ *     int x;
+ *     int y;
+ *   }
+ *   class Circle extends Shape {
+ *     int radius;
+ *   }
+ *   class Rectangle extends Shape {
+ *     int width;
+ *     int height;
+ *   }
+ *   class Diamond extends Shape {
+ *     int width;
+ *     int height;
+ *   }
+ *   class Drawing {
+ *     Shape bottomShape;
+ *     Shape topShape;
+ *   }
+ * }</pre>
+ * <p>Without additional type information, the serialized JSON is ambiguous. Is
+ * the bottom shape in this drawing a rectangle or a diamond? <pre>   {@code
+ *   {
+ *     "bottomShape": {
+ *       "width": 10,
+ *       "height": 5,
+ *       "x": 0,
+ *       "y": 0
+ *     },
+ *     "topShape": {
+ *       "radius": 2,
+ *       "x": 4,
+ *       "y": 1
+ *     }
+ *   }}</pre>
+ * This class addresses this problem by adding type information to the
+ * serialized JSON and honoring that type information when the JSON is
+ * deserialized: <pre>   {@code
+ *   {
+ *     "bottomShape": {
+ *       "type": "Diamond",
+ *       "width": 10,
+ *       "height": 5,
+ *       "x": 0,
+ *       "y": 0
+ *     },
+ *     "topShape": {
+ *       "type": "Circle",
+ *       "radius": 2,
+ *       "x": 4,
+ *       "y": 1
+ *     }
+ *   }}</pre>
+ * Both the type field name ({@code "type"}) and the type labels ({@code
+ * "Rectangle"}) are configurable.
+ *
+ * <h3>Registering Types</h3>
+ * Create a {@code RuntimeTypeAdapterFactory} by passing the base type and type field
+ * name to the {@link #of} factory method. If you don't supply an explicit type
+ * field name, {@code "type"} will be used. <pre>   {@code
+ *   RuntimeTypeAdapterFactory<Shape> shapeAdapterFactory
+ *       = RuntimeTypeAdapterFactory.of(Shape.class, "type");
+ * }</pre>
+ * Next register all of your subtypes. Every subtype must be explicitly
+ * registered. This protects your application from injection attacks. If you
+ * don't supply an explicit type label, the type's simple name will be used.
+ * <pre>   {@code
+ *   shapeAdapterFactory.registerSubtype(Rectangle.class, "Rectangle");
+ *   shapeAdapterFactory.registerSubtype(Circle.class, "Circle");
+ *   shapeAdapterFactory.registerSubtype(Diamond.class, "Diamond");
+ * }</pre>
+ * Finally, register the type adapter factory in your application's GSON builder:
+ * <pre>   {@code
+ *   Gson gson = new GsonBuilder()
+ *       .registerTypeAdapterFactory(shapeAdapterFactory)
+ *       .create();
+ * }</pre>
+ * Like {@code GsonBuilder}, this API supports chaining: <pre>   {@code
+ *   RuntimeTypeAdapterFactory<Shape> shapeAdapterFactory = RuntimeTypeAdapterFactory.of(Shape.class)
+ *       .registerSubtype(Rectangle.class)
+ *       .registerSubtype(Circle.class)
+ *       .registerSubtype(Diamond.class);
+ * }</pre>
+ */
+public final class RuntimeTypeAdapterFactory<T> implements TypeAdapterFactory {
+    private final Class<?> baseType;
+    private final String typeFieldName;
+    private final Map<String, Class<?>> labelToSubtype = new LinkedHashMap<String, Class<?>>();
+    private final Map<Class<?>, String> subtypeToLabel = new LinkedHashMap<Class<?>, String>();
+    private final boolean maintainType;
+
+    private RuntimeTypeAdapterFactory(Class<?> baseType, String typeFieldName, boolean maintainType) {
+        if (typeFieldName == null || baseType == null) {
+            throw new NullPointerException();
+        }
+        this.baseType = baseType;
+        this.typeFieldName = typeFieldName;
+        this.maintainType = maintainType;
+    }
+
+    /**
+     * Creates a new runtime type adapter using for {@code baseType} using {@code
+     * typeFieldName} as the type field name. Type field names are case sensitive.
+     * {@code maintainType} flag decide if the type will be stored in pojo or not.
+     */
+    public static <T> RuntimeTypeAdapterFactory<T> of(Class<T> baseType, String typeFieldName, boolean maintainType) {
+        return new RuntimeTypeAdapterFactory<T>(baseType, typeFieldName, maintainType);
+    }
+
+    /**
+     * Creates a new runtime type adapter using for {@code baseType} using {@code
+     * typeFieldName} as the type field name. Type field names are case sensitive.
+     */
+    public static <T> RuntimeTypeAdapterFactory<T> of(Class<T> baseType, String typeFieldName) {
+        return new RuntimeTypeAdapterFactory<T>(baseType, typeFieldName, false);
+    }
+
+    /**
+     * Creates a new runtime type adapter for {@code baseType} using {@code "type"} as
+     * the type field name.
+     */
+    public static <T> RuntimeTypeAdapterFactory<T> of(Class<T> baseType) {
+        return new RuntimeTypeAdapterFactory<T>(baseType, "type", false);
+    }
+
+    /**
+     * Registers {@code type} identified by {@code label}. Labels are case
+     * sensitive.
+     *
+     * @throws IllegalArgumentException if either {@code type} or {@code label}
+     *     have already been registered on this type adapter.
+     */
+    public RuntimeTypeAdapterFactory<T> registerSubtype(Class<? extends T> type, String label) {
+        if (type == null || label == null) {
+            throw new NullPointerException();
+        }
+        if (subtypeToLabel.containsKey(type) || labelToSubtype.containsKey(label)) {
+            throw new IllegalArgumentException("types and labels must be unique");
+        }
+        labelToSubtype.put(label, type);
+        subtypeToLabel.put(type, label);
+        return this;
+    }
+
+    /**
+     * Registers {@code type} identified by its {@link Class#getSimpleName simple
+     * name}. Labels are case sensitive.
+     *
+     * @throws IllegalArgumentException if either {@code type} or its simple name
+     *     have already been registered on this type adapter.
+     */
+    public RuntimeTypeAdapterFactory<T> registerSubtype(Class<? extends T> type) {
+        return registerSubtype(type, type.getSimpleName());
+    }
+
+    public <R> TypeAdapter<R> create(Gson gson, TypeToken<R> type) {
+        if (type.getRawType() != baseType) {
+            return null;
+        }
+
+        final Map<String, TypeAdapter<?>> labelToDelegate
+                = new LinkedHashMap<String, TypeAdapter<?>>();
+        final Map<Class<?>, TypeAdapter<?>> subtypeToDelegate
+                = new LinkedHashMap<Class<?>, TypeAdapter<?>>();
+        for (Map.Entry<String, Class<?>> entry : labelToSubtype.entrySet()) {
+            TypeAdapter<?> delegate = gson.getDelegateAdapter(this, TypeToken.get(entry.getValue()));
+            labelToDelegate.put(entry.getKey(), delegate);
+            subtypeToDelegate.put(entry.getValue(), delegate);
+        }
+
+        return new TypeAdapter<R>() {
+            @Override
+            public R read(JsonReader in) throws IOException {
+                JsonElement jsonElement = Streams.parse(in);
+                JsonElement labelJsonElement;
+                if (maintainType) {
+                    labelJsonElement = jsonElement.getAsJsonObject().get(typeFieldName);
+                } else {
+                    labelJsonElement = jsonElement.getAsJsonObject().remove(typeFieldName);
+                }
+
+                if (labelJsonElement == null) {
+                    throw new JsonParseException("cannot deserialize " + baseType
+                            + " because it does not define a field named " + typeFieldName);
+                }
+                String label = labelJsonElement.getAsString();
+                @SuppressWarnings("unchecked") // registration requires that subtype extends T
+                        TypeAdapter<R> delegate = (TypeAdapter<R>) labelToDelegate.get(label);
+                if (delegate == null) {
+                    throw new JsonParseException("cannot deserialize " + baseType + " subtype named "
+                            + label + "; did you forget to register a subtype?");
+                }
+                return delegate.fromJsonTree(jsonElement);
+            }
+
+            @Override
+            public void write(JsonWriter out, R value) throws IOException {
+                Class<?> srcType = value.getClass();
+                String label = subtypeToLabel.get(srcType);
+                @SuppressWarnings("unchecked") // registration requires that subtype extends T
+                        TypeAdapter<R> delegate = (TypeAdapter<R>) subtypeToDelegate.get(srcType);
+                if (delegate == null) {
+                    throw new JsonParseException("cannot serialize " + srcType.getName()
+                            + "; did you forget to register a subtype?");
+                }
+                JsonObject jsonObject = delegate.toJsonTree(value).getAsJsonObject();
+
+                if (maintainType) {
+                    Streams.write(jsonObject, out);
+                    return;
+                }
+
+                JsonObject clone = new JsonObject();
+
+                if (jsonObject.has(typeFieldName)) {
+                    throw new JsonParseException("cannot serialize " + srcType.getName()
+                            + " because it already defines a field named " + typeFieldName);
+                }
+                clone.add(typeFieldName, new JsonPrimitive(label));
+
+                for (Map.Entry<String, JsonElement> e : jsonObject.entrySet()) {
+                    clone.add(e.getKey(), e.getValue());
+                }
+                Streams.write(clone, out);
+            }
+        }.nullSafe();
+    }
+}
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/extensions/gson/typeAdapter.kt b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/gson/typeAdapter.kt
new file mode 100644
index 0000000..7d9b5af
--- /dev/null
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/extensions/gson/typeAdapter.kt
@@ -0,0 +1,22 @@
+package app.common
+
+import com.google.gson.GsonBuilder
+import com.google.gson.TypeAdapterFactory
+import com.simplemobiletools.clock.extensions.gson.RuntimeTypeAdapterFactory
+import com.simplemobiletools.clock.services.TimerState
+
+val timerStates = valueOf<TimerState>()
+    .registerSubtype(TimerState.Idle::class.java)
+    .registerSubtype(TimerState.Start::class.java)
+    .registerSubtype(TimerState.Running::class.java)
+    .registerSubtype(TimerState.Pause::class.java)
+    .registerSubtype(TimerState.Paused::class.java)
+    .registerSubtype(TimerState.Finish::class.java)
+
+inline fun <reified T: Any> valueOf(): RuntimeTypeAdapterFactory<T> = RuntimeTypeAdapterFactory.of(T::class.java)
+
+fun GsonBuilder.registerTypes(vararg types: TypeAdapterFactory) = apply {
+    types.forEach { registerTypeAdapterFactory(it) }
+}
+
+val gson = GsonBuilder().registerTypes(timerStates).create()
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/fragments/TimerFragment.kt b/app/src/main/kotlin/com/simplemobiletools/clock/fragments/TimerFragment.kt
index b8fe52c..d87dda1 100644
--- a/app/src/main/kotlin/com/simplemobiletools/clock/fragments/TimerFragment.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/fragments/TimerFragment.kt
@@ -1,51 +1,58 @@
 package com.simplemobiletools.clock.fragments
 
-import android.annotation.TargetApi
-import android.app.Notification
-import android.app.NotificationChannel
-import android.app.NotificationManager
-import android.content.Context
 import android.graphics.Color
 import android.media.AudioManager
-import android.os.Build
 import android.os.Bundle
-import android.os.CountDownTimer
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
-import androidx.core.app.NotificationCompat
 import androidx.fragment.app.Fragment
-import androidx.lifecycle.Observer
-import androidx.work.WorkInfo
-import androidx.work.WorkManager
 import com.simplemobiletools.clock.R
 import com.simplemobiletools.clock.activities.SimpleActivity
 import com.simplemobiletools.clock.dialogs.MyTimePickerDialogDialog
 import com.simplemobiletools.clock.extensions.*
-import com.simplemobiletools.clock.helpers.Config
 import com.simplemobiletools.clock.helpers.PICK_AUDIO_FILE_INTENT_ID
-import com.simplemobiletools.clock.helpers.TIMER_NOTIF_ID
-import com.simplemobiletools.clock.workers.*
+import com.simplemobiletools.clock.services.TimerState
+import com.simplemobiletools.clock.services.startTimerService
 import com.simplemobiletools.commons.dialogs.SelectAlarmSoundDialog
 import com.simplemobiletools.commons.extensions.*
 import com.simplemobiletools.commons.helpers.ALARM_SOUND_TYPE_ALARM
-import com.simplemobiletools.commons.helpers.isOreoPlus
 import com.simplemobiletools.commons.models.AlarmSound
 import kotlinx.android.synthetic.main.fragment_timer.view.*
-import java.util.concurrent.TimeUnit
-
+import org.greenrobot.eventbus.EventBus
+import org.greenrobot.eventbus.Subscribe
+import org.greenrobot.eventbus.ThreadMode
 
 class TimerFragment : Fragment() {
 
     lateinit var view: ViewGroup
-    private var timer: CountDownTimer? = null
-    private var isRunning = false
+    private var timerState: TimerState = TimerState.Idle
+
+    override fun onResume() {
+        super.onResume()
+
+        timerState = requiredActivity.config.timerState
+        updateViewStates(timerState)
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        EventBus.getDefault().register(this)
+    }
+
+    override fun onDestroy() {
+        EventBus.getDefault().unregister(this)
+        super.onDestroy()
+    }
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
         view = (inflater.inflate(R.layout.fragment_timer, container, false) as ViewGroup).apply {
             val config = requiredActivity.config
             val textColor = config.textColor
 
+            timer_time.text = 0.getFormattedDuration()
+
             requiredActivity.updateTextColors(timer_fragment)
             timer_play_pause.background = resources.getColoredDrawableWithColor(R.drawable.circle_background_filled, context!!.getAdjustedPrimaryColor())
             timer_reset.applyColorFilter(textColor)
@@ -60,27 +67,18 @@ class TimerFragment : Fragment() {
             timer_sound.colorLeftDrawable(textColor)
 
             timer_time.setOnClickListener {
-                if (isRunning) {
-                    pauseTimer(config)
-                } else {
-                    startTimer(config)
-                }
+                EventBus.getDefault().post(TimerState.Idle)
+                requiredActivity.hideTimerNotification()
+                requiredActivity.toast(R.string.timer_stopped)
             }
 
             timer_play_pause.setOnClickListener {
-                if (isRunning) {
-                    pauseTimer(config)
-                } else {
-                    startTimer(config)
-                }
+                context.startTimerService()
             }
 
             timer_reset.setOnClickListener {
-                cancelTimerWorker()
+                EventBus.getDefault().post(TimerState.Idle)
                 requiredActivity.hideTimerNotification()
-
-                config.timerTickStamp = 0L
-                config.timerStartStamp = 0L
                 requiredActivity.toast(R.string.timer_stopped)
             }
 
@@ -114,72 +112,46 @@ class TimerFragment : Fragment() {
                             context.checkAlarmsWithDeletedSoundUri(sound.uri)
                         })
             }
-
-            WorkManager.getInstance(requiredActivity).getWorkInfosByTagLiveData(TIMER_WORKER_KEY).observe(requiredActivity, Observer { workInfo ->
-                val workerState = workInfo?.firstOrNull()?.state
-                isRunning = (workerState == WorkInfo.State.ENQUEUED)
-
-                updateIcons(isRunning)
-                timer_reset.beVisibleIf(isRunning)
-                timer?.cancel()
-
-                when (workerState) {
-                    WorkInfo.State.ENQUEUED -> {
-                        val duration = config.timerSeconds.toLong() * 1000 //MS
-
-                        timer = object : CountDownTimer(duration, 1000) {
-                            override fun onTick(millisUntilFinished: Long) {
-                                timer_time.text = TimeUnit.MILLISECONDS.toSeconds(millisUntilFinished).toInt().getFormattedDuration()
-                            }
-
-                            override fun onFinish() {}
-                        }.start()
-                    }
-
-                    else -> {
-                        timer_time.text = 0.getFormattedDuration()
-                    }
-                }
-            })
-
-            cancelTimerWorker()
         }
 
         return view
     }
 
-    private fun startTimer(config: Config) {
-        val isTimerNoTick = config.timerTickStamp == 0L
-
-        if (isTimerNoTick) {
-            config.timerStartStamp = System.currentTimeMillis()
-
-            val selectedDuration = config.timerSeconds
-            val formattedTimestamp = config.timerStartStamp.timestampFormat("HH:mm:ss")
-
-            enqueueTimerWorker(TimeUnit.SECONDS.toMillis(selectedDuration.toLong()))
-            showNotification("(${selectedDuration.getFormattedDuration()}) $formattedTimestamp")
-        } else {
-            val duration = config.timerSeconds.toLong() * 1000 //MS
-            val selectedDuration = (config.timerStartStamp + duration) - (config.timerTickStamp - config.timerStartStamp)
-            val formattedTimestamp = config.timerStartStamp.timestampFormat("HH:mm:ss")
-
-            enqueueTimerWorker(TimeUnit.SECONDS.toMillis(selectedDuration.toLong()))
-            showNotification("(${selectedDuration.toInt().getFormattedDuration()}) $formattedTimestamp")
-        }
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun onMessageEvent(state: TimerState.Idle) {
+        view.timer_time.text = 0.getFormattedDuration()
+        updateViewStates(state)
     }
 
-    private fun pauseTimer(config: Config) {
-        cancelTimerWorker()
-        requiredActivity.hideTimerNotification()
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun onMessageEvent(state: TimerState.Running) {
+        view.timer_time.text = state.tick.div(1000).toInt().getFormattedDuration()
+        updateViewStates(state)
+    }
 
-        config.timerTickStamp = System.currentTimeMillis()
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun onMessageEvent(state: TimerState.Paused) {
+        updateViewStates(state)
+    }
 
-        val tick = config.timerTickStamp
-        val duration = config.timerSeconds.toLong() * 1000 //MS
-        val startedAt = config.timerStartStamp
-        val distance = duration - (tick - startedAt)
-        view.timer_time.text = distance.toInt().getFormattedDuration()
+    private fun updateViewStates(timerState: TimerState) {
+        view.timer_reset.beVisibleIf(timerState is TimerState.Running || timerState is TimerState.Paused)
+
+        val drawableId =
+                if (timerState is TimerState.Running) {
+                    R.drawable.ic_pause_vector
+                } else {
+                    R.drawable.ic_play_vector
+                }
+
+        val iconColor =
+                if (requiredActivity.getAdjustedPrimaryColor() == Color.WHITE) {
+                    Color.BLACK
+                } else {
+                    requiredActivity.config.textColor
+                }
+
+        view.timer_play_pause.setImageDrawable(resources.getColoredDrawableWithColor(drawableId, iconColor))
     }
 
     fun updateAlarmSound(alarmSound: AlarmSound) {
@@ -187,38 +159,4 @@ class TimerFragment : Fragment() {
         requiredActivity.config.timerSoundUri = alarmSound.uri
         view.timer_sound.text = alarmSound.title
     }
-
-    private fun updateIcons(isRunning: Boolean) {
-        val drawableId = if (isRunning) R.drawable.ic_pause_vector else R.drawable.ic_play_vector
-        val iconColor = if (requiredActivity.getAdjustedPrimaryColor() == Color.WHITE) Color.BLACK else requiredActivity.config.textColor
-        view.timer_play_pause.setImageDrawable(resources.getColoredDrawableWithColor(drawableId, iconColor))
-    }
-
-    @TargetApi(Build.VERSION_CODES.O)
-    private fun showNotification(formattedDuration: String) {
-        val channelId = "simple_alarm_timer"
-        val label = getString(R.string.timer)
-        val notificationManager = requiredActivity.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
-        if (isOreoPlus()) {
-            val importance = NotificationManager.IMPORTANCE_HIGH
-            NotificationChannel(channelId, label, importance).apply {
-                setSound(null, null)
-                notificationManager.createNotificationChannel(this)
-            }
-        }
-
-        val builder = NotificationCompat.Builder(context)
-                .setContentTitle(label)
-                .setContentText(formattedDuration)
-                .setSmallIcon(R.drawable.ic_timer)
-                .setContentIntent(context!!.getOpenTimerTabIntent())
-                .setPriority(Notification.PRIORITY_HIGH)
-                .setSound(null)
-                .setOngoing(true)
-                .setAutoCancel(true)
-                .setChannelId(channelId)
-
-        builder.setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
-        notificationManager.notify(TIMER_NOTIF_ID, builder.build())
-    }
 }
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/helpers/Config.kt b/app/src/main/kotlin/com/simplemobiletools/clock/helpers/Config.kt
index 9f2f8ab..6590627 100644
--- a/app/src/main/kotlin/com/simplemobiletools/clock/helpers/Config.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/helpers/Config.kt
@@ -1,10 +1,15 @@
 package com.simplemobiletools.clock.helpers
 
 import android.content.Context
+import app.common.gson
+import com.google.gson.Gson
+import com.simplemobiletools.clock.services.StateWrapper
+import com.simplemobiletools.clock.services.TimerState
 import com.simplemobiletools.commons.extensions.getDefaultAlarmTitle
 import com.simplemobiletools.commons.extensions.getDefaultAlarmUri
 import com.simplemobiletools.commons.helpers.ALARM_SOUND_TYPE_ALARM
 import com.simplemobiletools.commons.helpers.BaseConfig
+import java.sql.Time
 
 class Config(context: Context) : BaseConfig(context) {
     companion object {
@@ -27,13 +32,11 @@ class Config(context: Context) : BaseConfig(context) {
         get() = prefs.getInt(TIMER_SECONDS, 300)
         set(lastTimerSeconds) = prefs.edit().putInt(TIMER_SECONDS, lastTimerSeconds).apply()
 
-    var timerStartStamp: Long
-        get() = prefs.getLong(TIMER_START_TIMESTAMP, 0L)
-        set(timestamp) = prefs.edit().putLong(TIMER_START_TIMESTAMP, timestamp).apply()
-
-    var timerTickStamp: Long
-        get() = prefs.getLong(TIMER_TICK_TIMESTAMP, 0L)
-        set(timestamp) = prefs.edit().putLong(TIMER_TICK_TIMESTAMP, timestamp).apply()
+    var timerState: TimerState
+        get() = prefs.getString(TIMER_STATE, null)?.let { state ->
+            gson.fromJson(state, StateWrapper::class.java)
+        }?.state ?: TimerState.Idle
+        set(state) = prefs.edit().putString(TIMER_STATE, gson.toJson(StateWrapper(state))).apply()
 
     var timerVibrate: Boolean
         get() = prefs.getBoolean(TIMER_VIBRATE, false)
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/helpers/Constants.kt b/app/src/main/kotlin/com/simplemobiletools/clock/helpers/Constants.kt
index f383d54..c58f2a5 100644
--- a/app/src/main/kotlin/com/simplemobiletools/clock/helpers/Constants.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/helpers/Constants.kt
@@ -9,7 +9,7 @@ const val SELECTED_TIME_ZONES = "selected_time_zones"
 const val EDITED_TIME_ZONE_TITLES = "edited_time_zone_titles"
 const val TIMER_SECONDS = "timer_seconds"
 const val TIMER_START_TIMESTAMP = "timer_timetamp"
-const val TIMER_TICK_TIMESTAMP = "timer_tick"
+const val TIMER_STATE = "timer_state"
 const val TIMER_VIBRATE = "timer_vibrate"
 const val TIMER_SOUND_URI = "timer_sound_uri"
 const val TIMER_SOUND_TITLE = "timer_sound_title"
@@ -32,6 +32,7 @@ const val UPDATE_WIDGET_INTENT_ID = 9997
 const val OPEN_APP_INTENT_ID = 9998
 const val ALARM_NOTIF_ID = 9998
 const val TIMER_NOTIF_ID = 9999
+const val TIMER_RUNNING_NOTIF_ID = 10000
 
 const val OPEN_TAB = "open_tab"
 const val TAB_CLOCK = 0
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/services/timerService.kt b/app/src/main/kotlin/com/simplemobiletools/clock/services/timerService.kt
new file mode 100644
index 0000000..1cac5e4
--- /dev/null
+++ b/app/src/main/kotlin/com/simplemobiletools/clock/services/timerService.kt
@@ -0,0 +1,156 @@
+package com.simplemobiletools.clock.services
+
+import android.annotation.TargetApi
+import android.app.Notification
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.Service
+import android.content.Context
+import android.content.Intent
+import android.os.Build
+import android.os.CountDownTimer
+import android.os.IBinder
+import androidx.core.app.NotificationCompat
+import com.simplemobiletools.clock.R
+import com.simplemobiletools.clock.extensions.*
+import com.simplemobiletools.clock.helpers.TIMER_NOTIF_ID
+import com.simplemobiletools.clock.helpers.TIMER_RUNNING_NOTIF_ID
+import com.simplemobiletools.commons.extensions.getFormattedDuration
+import com.simplemobiletools.commons.helpers.isOreoPlus
+import org.greenrobot.eventbus.EventBus
+import org.greenrobot.eventbus.Subscribe
+import org.greenrobot.eventbus.ThreadMode
+
+fun Context.startTimerService() {
+    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+        startForegroundService(Intent(this, TimerService::class.java))
+    } else {
+        startService(Intent(this, TimerService::class.java))
+    }
+}
+
+class TimerService : Service() {
+
+    private var timer: CountDownTimer? = null
+    private var lastTick = 0L
+    private val bus = EventBus.getDefault()
+
+    override fun onCreate() {
+        super.onCreate()
+        bus.register(this)
+    }
+
+    override fun onBind(intent: Intent?): IBinder? = null
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        super.onStartCommand(intent, flags, startId)
+
+        val formattedDuration = config.timerSeconds.getFormattedDuration()
+        startForeground(TIMER_RUNNING_NOTIF_ID, notification(formattedDuration))
+
+        when (val state = config.timerState) {
+            is TimerState.Idle -> bus.post(TimerState.Start(config.timerSeconds.secondsToMillis))
+            is TimerState.Paused -> bus.post(TimerState.Start(state.tick))
+            is TimerState.Running -> bus.post(TimerState.Pause(state.tick))
+            else -> {}
+        }
+
+        return START_NOT_STICKY
+    }
+
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun onMessageEvent(state: TimerState.Idle) {
+        config.timerState = state
+        timer?.cancel()
+        stopService()
+    }
+
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun onMessageEvent(state: TimerState.Start) {
+        timer = object : CountDownTimer(state.duration, 1000) {
+            override fun onTick(tick: Long) {
+                lastTick = tick
+
+                val newState = TimerState.Running(state.duration, tick)
+                bus.post(newState)
+                config.timerState = newState
+            }
+
+            override fun onFinish() {
+                bus.post(TimerState.Finish(state.duration))
+            }
+        }.start()
+    }
+
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun onMessageEvent(event: TimerState.Finish) {
+        val pendingIntent = getOpenTimerTabIntent()
+        val notification = getTimerNotification(pendingIntent, false) //MAYBE IN FUTURE ADD TIME TO NOTIFICATION
+        val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+
+        notificationManager.notify(TIMER_NOTIF_ID, notification)
+
+        bus.post(TimerState.Idle)
+    }
+
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun onMessageEvent(event: TimerState.Pause) {
+        bus.post(TimerState.Paused(event.duration, lastTick))
+    }
+
+    @Subscribe(threadMode = ThreadMode.MAIN)
+    fun onMessageEvent(state: TimerState.Paused) {
+        config.timerState = state
+        timer?.cancel()
+        stopService()
+    }
+
+    private fun stopService() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) stopForeground(true)
+        else stopSelf()
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        bus.unregister(this)
+    }
+
+    @TargetApi(Build.VERSION_CODES.O)
+    private fun notification(formattedDuration: String): Notification {
+        val channelId = "simple_alarm_timer"
+        val label = getString(R.string.timer)
+        val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+        if (isOreoPlus()) {
+            val importance = NotificationManager.IMPORTANCE_HIGH
+            NotificationChannel(channelId, label, importance).apply {
+                setSound(null, null)
+                notificationManager.createNotificationChannel(this)
+            }
+        }
+
+        val builder = NotificationCompat.Builder(this)
+                .setContentTitle(label)
+                .setContentText(formattedDuration)
+                .setSmallIcon(R.drawable.ic_timer)
+                .setContentIntent(this.getOpenTimerTabIntent())
+                .setPriority(Notification.PRIORITY_HIGH)
+                .setSound(null)
+                .setOngoing(true)
+                .setAutoCancel(true)
+                .setChannelId(channelId)
+
+        builder.setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
+        return builder.build()
+    }
+}
+
+data class StateWrapper(val state: TimerState)
+
+sealed class TimerState {
+    object Idle: TimerState()
+    data class Start(val duration: Long): TimerState()
+    data class Running(val duration: Long, val tick: Long): TimerState()
+    data class Pause(val duration: Long): TimerState()
+    data class Paused(val duration: Long, val tick: Long): TimerState()
+    data class Finish(val duration: Long): TimerState()
+}
diff --git a/app/src/main/kotlin/com/simplemobiletools/clock/workers/timerWorker.kt b/app/src/main/kotlin/com/simplemobiletools/clock/workers/timerWorker.kt
deleted file mode 100644
index 1bb655c..0000000
--- a/app/src/main/kotlin/com/simplemobiletools/clock/workers/timerWorker.kt
+++ /dev/null
@@ -1,41 +0,0 @@
-package com.simplemobiletools.clock.workers
-
-import android.content.Context
-import androidx.fragment.app.Fragment
-import androidx.work.*
-import com.simplemobiletools.clock.extensions.*
-import java.util.*
-import java.util.concurrent.TimeUnit
-
-private const val TIMER_REQUEST_ID = "TIMER_REQUEST_ID"
-const val TIMER_WORKER_KEY = "TIMER_WORKER_KEY"
-
-private fun Fragment.saveTimerRequestId(uuid: UUID) =
-        preferences.edit().putString(TIMER_REQUEST_ID, uuid.toString()).apply()
-
-val Fragment.timerRequestId: UUID?
-    get() =
-        preferences.getString(TIMER_REQUEST_ID, UUID.randomUUID().toString())?.let { UUID.fromString(it) }
-
-fun Fragment.cancelTimerWorker() =
-        WorkManager.getInstance(requiredActivity).cancelAllWorkByTag(TIMER_WORKER_KEY)
-
-fun Fragment.enqueueTimerWorker(delay: Long) =
-        WorkManager.getInstance(requiredActivity).enqueueUniqueWork(TIMER_WORKER_KEY, ExistingWorkPolicy.REPLACE, timerRequest(delay))
-
-private fun Fragment.timerRequest(delay: Long): OneTimeWorkRequest =
-        OneTimeWorkRequestBuilder<TimerWorker>().setInitialDelay(delay, TimeUnit.MILLISECONDS).addTag(TIMER_WORKER_KEY).build().also {
-        saveTimerRequestId(it.id)
-}
-
-class TimerWorker(val context: Context, workerParams: WorkerParameters) : Worker(context, workerParams) {
-    override fun doWork(): Result =
-            try {
-                context.showTimerNotification(false)
-                context.config.timerTickStamp = 0L
-                context.config.timerStartStamp = 0L
-                Result.success()
-            } catch (exception: Exception) {
-                Result.failure()
-            }
-}