diff --git a/build.gradle b/build.gradle
index 865c0621..ba01cd11 100644
--- a/build.gradle
+++ b/build.gradle
@@ -29,8 +29,12 @@ buildConfig {
     packageName = 'app'
     buildConfigField 'int', 'VERSION_CODE', '1'
     buildConfigField 'String', 'VERSION', '0.0.1'
-    buildConfigField "String", "PROFILE_URL", "https://sourcerer.io/"
-    buildConfigField "String", "API_BASE_URL", "http://localhost:3181"
+    buildConfigField 'String', 'PROFILE_URL', 'https://sourcerer.io/'
+    buildConfigField 'String', 'API_BASE_URL', 'http://localhost:3181'
+    buildConfigField 'String', 'GA_BASE_PATH', 'http://www.google-analytics.com'
+    buildConfigField 'String', 'GA_TRACKING_ID', 'UA-107129190-2'
+    buildConfigField 'boolean', 'IS_GA_ENABLED', 'true'
+    buildConfig
 }
 
 junitPlatform {
diff --git a/src/main/kotlin/app/Analytics.kt b/src/main/kotlin/app/Analytics.kt
new file mode 100644
index 00000000..ecbe740e
--- /dev/null
+++ b/src/main/kotlin/app/Analytics.kt
@@ -0,0 +1,145 @@
+// Copyright 2017 Sourcerer Inc. All Rights Reserved.
+// Author: Anatoly Kislov (anatoly@sourcerer.io)
+
+package app
+
+import com.github.kittinunf.fuel.core.FuelError
+import com.github.kittinunf.fuel.core.FuelManager
+import com.github.kittinunf.fuel.core.Method
+import com.github.kittinunf.fuel.core.Request
+import com.google.protobuf.InvalidProtocolBufferException
+import java.security.InvalidParameterException
+
+typealias Param = Pair<String, String>
+
+/**
+ * Google Analytics events tracking.
+ */
+object Analytics {
+    private val IS_ENABLED = BuildConfig.IS_GA_ENABLED
+    private val BASE_PATH = BuildConfig.GA_BASE_PATH
+    private val BASE_URL = "/virtual/app/"
+    private val PROTOCOL_VERSION = "1"
+    private val TRACKING_ID = BuildConfig.GA_TRACKING_ID
+    private val DATA_SOURCE = "app"
+
+    private val HIT_PAGEVIEW = "pageview"
+    private val HIT_EXCEPTION = "exception"
+
+    private val fuelManager = FuelManager()
+
+    var uuid: String = ""  // Should be set on start of the app.
+    var username: String = ""  // Should be set on successful authorization.
+
+    init {
+        fuelManager.basePath = BASE_PATH
+    }
+
+    private fun post(params: List<Param>): Request {
+        return fuelManager.request(Method.POST, "/collect", params)
+    }
+
+    /**
+     * Google Analytics Measurement Protocol is used to track events.
+     * User iteration data is sent to GA endpoint via POST request.
+     * Events (or hits) mapped to virtual urls with "Data Source" parameter.
+     * Used parameters:
+     * - v: Protocol Version (Required)
+     * - tid: Tracking ID - used to specify GA account (Required)
+     * - cid: Client ID - anonymous client id (UUID type 4)
+     * - uid: User ID - username
+     * - t: Hit Type - type of event
+     * - dp: Document Path - virtual url
+     */
+    private fun trackEvent(event: String, params: List<Param> = listOf()) {
+        if (!IS_ENABLED || (username.isEmpty() && uuid.isEmpty())) {
+            return
+        }
+
+        val idParams = mutableListOf<Param>()
+        if (uuid.isNotEmpty()) {
+            idParams.add("cid" to uuid)
+        }
+        if (username.isNotEmpty()) {
+            idParams.add("uid" to username)
+        }
+
+        val defaultParams = listOf("v" to PROTOCOL_VERSION,
+                                   "tid" to TRACKING_ID,
+                                   "ds" to DATA_SOURCE,
+                                   "t" to HIT_PAGEVIEW,
+                                   "dp" to BASE_URL + event)
+
+        try {
+            // Send event to GA with united params.
+            post(params + defaultParams.filter { !params.contains(it) }
+                + idParams).responseString()
+        } catch (e: Throwable) {
+            Logger.error("Error while sending error report", e, logOnly = true)
+        }
+    }
+
+    fun trackStart() {
+        trackEvent("start")
+    }
+
+    fun trackAuth() {
+        trackEvent("auth")
+    }
+
+    fun trackConfigSetup() {
+        trackEvent("config/setup")
+    }
+
+    fun trackConfigChanged() {
+        trackEvent("config/changed")
+    }
+
+    fun trackHashingRepoSuccess() {
+        trackEvent("hashing/repo/success")
+    }
+
+    fun trackHashingSuccess() {
+        trackEvent("hashing/success")
+    }
+
+    fun trackError(e: Throwable? = null, code: String = "") {
+        val url = if (e != null) getErrorUrl(e) else code
+        val separator = if (url.isNotEmpty()) "/" else ""
+        trackEvent("error" + separator + url, listOf("t" to HIT_EXCEPTION))
+    }
+
+    fun trackExit() {
+        trackEvent("exit")
+    }
+
+    private fun getErrorUrl(e: Throwable): String {
+        // Mapping for request exceptions.
+        when (e) {
+            is FuelError -> return "request"
+            is InvalidParameterException -> return "request/parsing"
+            is InvalidProtocolBufferException -> return "request/parsing"
+        }
+
+        // Get concrete class of exception name removing all common parts.
+        val name = e.javaClass.simpleName.replace("Exception", "")
+                                         .replace("Error", "")
+                                         .replace("Throwable", "")
+
+        if (name.length == 0 || name.length == 1) {
+            return name
+        }
+
+        // Divide CamelCased words in class name by dashes.
+        val nameCapitalized = name.toUpperCase()
+        var url = name[0].toString()
+        for (i in 1..name.length - 1) {
+            if (name[i] == nameCapitalized[i]) {
+                url += "-"
+            }
+            url += name[i]
+        }
+
+        return url.toLowerCase()
+    }
+}
diff --git a/src/main/kotlin/app/Logger.kt b/src/main/kotlin/app/Logger.kt
index a8bf6cd8..0b2d913f 100644
--- a/src/main/kotlin/app/Logger.kt
+++ b/src/main/kotlin/app/Logger.kt
@@ -34,19 +34,19 @@ object Logger {
 
     /**
      * Log error message with exception info.
+     *
+     * @property message the message for user and logs.
+     * @property e the exception if presented.
+     * @property code the code of error if exception is not presented.
      */
-    fun error(message: String) {
+    fun error(message: String, e: Throwable? = null, code: String = "",
+              logOnly: Boolean = false) {
         if (LEVEL >= ERROR) {
-            println("[e] $message.")
+            println("[e] $message" + if (e != null) ": $e" else "")
         }
-    }
-
-    /**
-     * Log error message with exception info.
-     */
-    fun error(message: String, e: Throwable) {
-        if (LEVEL >= ERROR) {
-            println("[e] $message: $e")
+        if (!logOnly) {
+            Analytics.trackError(e = e, code = code)
+            //TODO(anatoly): Add error tracking software.
         }
     }
 
diff --git a/src/main/kotlin/app/Main.kt b/src/main/kotlin/app/Main.kt
index 88122558..72be7309 100644
--- a/src/main/kotlin/app/Main.kt
+++ b/src/main/kotlin/app/Main.kt
@@ -19,6 +19,9 @@ import com.beust.jcommander.JCommander
 import com.beust.jcommander.MissingCommandException
 
 fun main(argv : Array<String>) {
+    Thread.setDefaultUncaughtExceptionHandler { _, e: Throwable? ->
+        Logger.error("Uncaught exception", e)
+    }
     Main(argv)
 }
 
@@ -27,6 +30,9 @@ class Main(argv: Array<String>) {
     private val api = ServerApi(configurator)
 
     init {
+        Analytics.uuid = configurator.getUuidPersistent()
+        Analytics.trackStart()
+
         val options = Options()
         val commandAdd = CommandAdd()
         val commandConfig = CommandConfig()
@@ -58,8 +64,13 @@ class Main(argv: Array<String>) {
                 else -> startUi()
             }
         } catch (e: MissingCommandException) {
-            Logger.error("No such command: ${e.unknownCommand}")
+            Logger.error(
+                message = "No such command: ${e.unknownCommand}",
+                code = "no-command"
+            )
         }
+
+        Analytics.trackExit()
     }
 
     private fun startUi() {
@@ -74,8 +85,11 @@ class Main(argv: Array<String>) {
             configurator.addLocalRepoPersistent(localRepo)
             configurator.saveToFile()
             println("Added git repository at $path.")
+
+            Analytics.trackConfigChanged()
         } else {
-            Logger.error("No valid git repository found at $path.")
+            Logger.error(message = "No valid git repository found at $path.",
+                         code = "repo-invalid")
         }
     }
 
@@ -83,7 +97,8 @@ class Main(argv: Array<String>) {
         val (key, value) = commandOptions.pair
 
         if (!arrayListOf("username", "password").contains(key)) {
-            Logger.error("No such key $key")
+            Logger.error(message = "No such key $key",
+                         code = "invalid-params")
             return
         }
 
@@ -93,6 +108,8 @@ class Main(argv: Array<String>) {
         }
 
         configurator.saveToFile()
+
+        Analytics.trackConfigChanged()
     }
 
     private fun doList() {
@@ -108,6 +125,8 @@ class Main(argv: Array<String>) {
             configurator.removeLocalRepoPersistent(LocalRepo(path))
             configurator.saveToFile()
             println("Repository removed from tracking list.")
+
+            Analytics.trackConfigChanged()
         } else {
             println("Repository not found in tracking list.")
         }
diff --git a/src/main/kotlin/app/api/ServerApi.kt b/src/main/kotlin/app/api/ServerApi.kt
index a375b046..58312f1d 100644
--- a/src/main/kotlin/app/api/ServerApi.kt
+++ b/src/main/kotlin/app/api/ServerApi.kt
@@ -13,8 +13,8 @@ import app.model.FactGroup
 import app.model.Repo
 import app.model.User
 import app.utils.RequestException
-import com.github.kittinunf.fuel.Fuel
 import com.github.kittinunf.fuel.core.FuelManager
+import com.github.kittinunf.fuel.core.Method
 import com.github.kittinunf.fuel.core.Request
 import com.github.kittinunf.fuel.core.Response
 import com.google.protobuf.InvalidProtocolBufferException
@@ -30,6 +30,7 @@ class ServerApi (private val configurator: Configurator) : Api {
         private val KEY_TOKEN = "Token="
     }
 
+    private val fuelManager = FuelManager()
     private var token = ""
 
     private fun cookieRequestInterceptor() = { req: Request ->
@@ -50,7 +51,6 @@ class ServerApi (private val configurator: Configurator) : Api {
     }
 
     init {
-        val fuelManager = FuelManager.instance
         fuelManager.basePath = BuildConfig.API_BASE_URL
         fuelManager.addRequestInterceptor { cookieRequestInterceptor() }
         fuelManager.addResponseInterceptor { cookieResponseInterceptor() }
@@ -62,38 +62,49 @@ class ServerApi (private val configurator: Configurator) : Api {
     private val password
         get() = configurator.getPassword()
 
+    private fun post(path: String): Request {
+        return fuelManager.request(Method.POST, path)
+    }
+
+    private fun get(path: String): Request {
+        return fuelManager.request(Method.GET, path)
+    }
+
+    private fun delete(path: String): Request {
+        return fuelManager.request(Method.DELETE, path)
+    }
+
     private fun createRequestGetToken(): Request {
-        return Fuel.post("/auth").authenticate(username, password)
+        return post("/auth").authenticate(username, password)
                    .header(getVersionCodeHeader())
     }
 
     private fun createRequestGetUser(): Request {
-        return Fuel.get("/user")
+        return get("/user")
     }
 
     private fun createRequestGetRepo(repoRehash: String): Request {
-        return Fuel.get("/repo/$repoRehash")
+        return get("/repo/$repoRehash")
     }
 
     private fun createRequestPostRepo(repo: Repo): Request {
-        return Fuel.post("/repo").header(getContentTypeHeader())
-                   .body(repo.serialize())
+        return post("/repo").header(getContentTypeHeader())
+                            .body(repo.serialize())
     }
 
     private fun createRequestPostCommits(commits: CommitGroup): Request {
-        return Fuel.post("/commits").header(getContentTypeHeader())
-                   .body(commits.serialize())
+        return post("/commits").header(getContentTypeHeader())
+                               .body(commits.serialize())
     }
 
     private fun createRequestDeleteCommits(commits: CommitGroup): Request {
-        return Fuel.delete("/commits").header(getContentTypeHeader())
-                   .body(commits.serialize())
+        return delete("/commits").header(getContentTypeHeader())
+                                 .body(commits.serialize())
     }
 
-    private fun createRequestPostFacts(facts: FactGroup):
-        Request {
-        return Fuel.post("/facts").header(getContentTypeHeader())
-                   .body(facts.serialize())
+    private fun createRequestPostFacts(facts: FactGroup): Request {
+        return post("/facts").header(getContentTypeHeader())
+                             .body(facts.serialize())
     }
 
     private fun <T> makeRequest(request: Request,
@@ -102,13 +113,13 @@ class ServerApi (private val configurator: Configurator) : Api {
         try {
             Logger.debug("Request $requestName initialized")
             val (_, res, result) = request.responseString()
-            val (_, error) = result
-            if (error == null) {
+            val (_, e) = result
+            if (e == null) {
                 Logger.debug("Request $requestName success")
                 return parser(res.data)
             } else {
-                Logger.error("Request $requestName error", error)
-                throw RequestException(error)
+                Logger.error("Request $requestName error", e)
+                throw RequestException(e)
             }
         } catch (e: InvalidProtocolBufferException) {
             Logger.error("Request $requestName error while parsing", e)
diff --git a/src/main/kotlin/app/config/Config.kt b/src/main/kotlin/app/config/Config.kt
index cf1cabca..98b4fa51 100644
--- a/src/main/kotlin/app/config/Config.kt
+++ b/src/main/kotlin/app/config/Config.kt
@@ -10,6 +10,7 @@ import app.utils.Options
  * Config data class.
  */
 class Config (
+        var uuid: String = "",
         var username: String = "",
         var password: String = "",
         var localRepos: MutableSet<LocalRepo> = mutableSetOf()
diff --git a/src/main/kotlin/app/config/Configurator.kt b/src/main/kotlin/app/config/Configurator.kt
index a54033ac..0cab1036 100644
--- a/src/main/kotlin/app/config/Configurator.kt
+++ b/src/main/kotlin/app/config/Configurator.kt
@@ -16,6 +16,7 @@ interface Configurator {
     fun getRepos(): List<Repo>
     fun setUsernameCurrent(username: String)
     fun setPasswordCurrent(password: String)
+    fun getUuidPersistent(): String
     fun setUsernamePersistent(username: String)
     fun setPasswordPersistent(password: String)
     fun addLocalRepoPersistent(localRepo: LocalRepo)
diff --git a/src/main/kotlin/app/config/FileConfigurator.kt b/src/main/kotlin/app/config/FileConfigurator.kt
index 684873d6..117e9b22 100644
--- a/src/main/kotlin/app/config/FileConfigurator.kt
+++ b/src/main/kotlin/app/config/FileConfigurator.kt
@@ -21,6 +21,7 @@ import java.nio.file.Files
 import java.nio.file.InvalidPathException
 import java.nio.file.NoSuchFileException
 import java.nio.file.Paths
+import java.util.UUID
 
 /**
  * Singleton class that manage configs and CLI options.
@@ -85,6 +86,17 @@ class FileConfigurator : Configurator {
      */
     init {
         loadFromFile()
+        assignUuidIfMissing()
+    }
+
+    /**
+     * Generates UUID for analytics on install.
+     */
+    private fun assignUuidIfMissing() {
+        if (persistent.uuid.isNotEmpty()) {
+            return
+        }
+        persistent.uuid = UUID.randomUUID().toString()
     }
 
     /**
@@ -152,6 +164,13 @@ class FileConfigurator : Configurator {
         current.password = PasswordHelper.hashPassword(password)
     }
 
+    /**
+     * Gets UUID.
+     */
+    override fun getUuidPersistent(): String {
+        return persistent.uuid
+    }
+
     /**
      * Sets username to persistent config. Use [saveToFile] to save.
      */
diff --git a/src/main/kotlin/app/config/MockConfigurator.kt b/src/main/kotlin/app/config/MockConfigurator.kt
index 521401bb..1b482c23 100644
--- a/src/main/kotlin/app/config/MockConfigurator.kt
+++ b/src/main/kotlin/app/config/MockConfigurator.kt
@@ -13,7 +13,8 @@ class MockConfigurator(var mockUsername: String = "",
                        var mockIsFirstLaunch: Boolean = true,
                        var mockRepos: MutableList<Repo> = mutableListOf(),
                        var mockLocalRepos: MutableList<LocalRepo> =
-                           mutableListOf()) : Configurator {
+                           mutableListOf(),
+                       var uuid: String = "") : Configurator {
     var mockCurrent: Config = Config()
     var mockPersistent: Config = Config()
     var mockOptions: Options = Options()
@@ -50,6 +51,10 @@ class MockConfigurator(var mockUsername: String = "",
         mockCurrent.password = password
     }
 
+    override fun getUuidPersistent(): String {
+        return uuid
+    }
+
     override fun setUsernamePersistent(username: String) {
         mockPersistent.username = username
     }
diff --git a/src/main/kotlin/app/hashers/RepoHasher.kt b/src/main/kotlin/app/hashers/RepoHasher.kt
index 240f1cf0..7004013c 100644
--- a/src/main/kotlin/app/hashers/RepoHasher.kt
+++ b/src/main/kotlin/app/hashers/RepoHasher.kt
@@ -3,6 +3,7 @@
 
 package app.hashers
 
+import app.Analytics
 import app.Logger
 import app.api.Api
 import app.config.Configurator
@@ -53,7 +54,7 @@ class RepoHasher(private val localRepo: LocalRepo, private val api: Api,
             val errors = mutableListOf<Throwable>()
             val onError: (Throwable) -> Unit = {
                 e -> errors.add(e)
-                Logger.error("Error while hashing:", e)
+                Logger.error("Hashing error", e)
             }
 
             // Hash by all plugins.
@@ -82,6 +83,7 @@ class RepoHasher(private val localRepo: LocalRepo, private val api: Api,
             }
 
             println("Hashing $localRepo successfully finished.")
+            Analytics.trackHashingRepoSuccess()
         }
         finally {
             closeGit(git)
diff --git a/src/main/kotlin/app/ui/AddRepoState.kt b/src/main/kotlin/app/ui/AddRepoState.kt
index bd89671f..e36156db 100644
--- a/src/main/kotlin/app/ui/AddRepoState.kt
+++ b/src/main/kotlin/app/ui/AddRepoState.kt
@@ -3,6 +3,7 @@
 
 package app.ui
 
+import app.Analytics
 import app.api.Api
 import app.config.Configurator
 import app.model.LocalRepo
@@ -44,6 +45,8 @@ class AddRepoState constructor(private val context: Context,
                 }
             }
         }
+
+        Analytics.trackConfigSetup()
     }
 
     override fun next() {
diff --git a/src/main/kotlin/app/ui/AuthState.kt b/src/main/kotlin/app/ui/AuthState.kt
index a68f2ccf..627b63e1 100644
--- a/src/main/kotlin/app/ui/AuthState.kt
+++ b/src/main/kotlin/app/ui/AuthState.kt
@@ -3,6 +3,7 @@
 
 package app.ui
 
+import app.Analytics
 import app.BuildConfig
 import app.api.Api
 import app.config.Configurator
@@ -74,6 +75,10 @@ class AuthState constructor(private val context: Context,
             println("You are successfully authenticated. Your profile page is "
                     + BuildConfig.PROFILE_URL + configurator.getUsername())
             saveCredentialsIfChanged()
+
+            Analytics.username = configurator.getUsername()
+            Analytics.trackAuth()
+
             return true
         } catch (e: RequestException) {
             if (e.isAuthError) {
diff --git a/src/main/kotlin/app/ui/UpdateRepoState.kt b/src/main/kotlin/app/ui/UpdateRepoState.kt
index 159da0c1..925a4c23 100644
--- a/src/main/kotlin/app/ui/UpdateRepoState.kt
+++ b/src/main/kotlin/app/ui/UpdateRepoState.kt
@@ -3,6 +3,7 @@
 
 package app.ui
 
+import app.Analytics
 import app.hashers.RepoHasher
 import app.Logger
 import app.api.Api
@@ -33,6 +34,8 @@ class UpdateRepoState constructor(private val context: Context,
         }
         println("The repositories have been hashed. See result online on your "
                 + "Sourcerer profile.")
+
+        Analytics.trackHashingSuccess()
     }
 
     override fun next() {
diff --git a/src/main/kotlin/app/utils/RepoHelper.kt b/src/main/kotlin/app/utils/RepoHelper.kt
index ff87f00b..2cb5f3de 100644
--- a/src/main/kotlin/app/utils/RepoHelper.kt
+++ b/src/main/kotlin/app/utils/RepoHelper.kt
@@ -32,7 +32,7 @@ object RepoHelper {
             repository = git.repository
             commitId = repository.resolve(MASTER_BRANCH)
         } catch (e: Exception) {
-            Logger.error("Cannot access repository at path $path", e)
+           Logger.error("Cannot access repository at path $path", e)
             return false
         } finally {
             repository?.close()
@@ -42,7 +42,6 @@ object RepoHelper {
         if (commitId != null) {
             return true
         }
-        Logger.error("Repository at path $path is empty")
         return false
     }