diff --git a/uhabits-server/build.gradle.kts b/uhabits-server/build.gradle.kts
index 197fd4c30..bfe94836a 100644
--- a/uhabits-server/build.gradle.kts
+++ b/uhabits-server/build.gradle.kts
@@ -23,9 +23,9 @@ plugins {
     application
     id("kotlin")
     id("com.github.johnrengelman.shadow") version "7.1.0"
+    id("org.jlleitschuh.gradle.ktlint")
 }
 
-
 application {
     group = "org.isoron.uhabits"
     version = "0.0.1"
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/SyncData.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/SyncData.kt
index d60319d6e..65fcd1ae9 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/SyncData.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/SyncData.kt
@@ -19,7 +19,7 @@
 
 package org.isoron.uhabits.sync
 
-import com.fasterxml.jackson.databind.*
+import com.fasterxml.jackson.databind.ObjectMapper
 
 data class SyncData(
     val version: Long,
@@ -32,4 +32,4 @@ data class GetDataVersionResponse(val version: Long)
 
 val defaultMapper = ObjectMapper()
 fun SyncData.toJson(): String = defaultMapper.writeValueAsString(this)
-fun GetDataVersionResponse.toJson(): String = defaultMapper.writeValueAsString(this)
\ No newline at end of file
+fun GetDataVersionResponse.toJson(): String = defaultMapper.writeValueAsString(this)
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/SyncException.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/SyncException.kt
index 30689ad86..7a8d615f3 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/SyncException.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/SyncException.kt
@@ -19,10 +19,10 @@
 
 package org.isoron.uhabits.sync
 
-open class SyncException: RuntimeException()
+open class SyncException : RuntimeException()
 
-class KeyNotFoundException: SyncException()
+class KeyNotFoundException : SyncException()
 
-class ServiceUnavailable: SyncException()
+class ServiceUnavailable : SyncException()
 
-class EditConflictException: SyncException()
\ No newline at end of file
+class EditConflictException : SyncException()
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/MetricsModule.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/MetricsModule.kt
index f367dd552..379f96ad8 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/MetricsModule.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/MetricsModule.kt
@@ -19,15 +19,15 @@
 
 package org.isoron.uhabits.sync.app
 
-import io.ktor.application.*
-import io.ktor.http.*
-import io.ktor.response.*
-import io.ktor.routing.*
-import io.prometheus.client.*
-import io.prometheus.client.exporter.common.*
-import io.prometheus.client.hotspot.*
-import java.io.*
-
+import io.ktor.application.call
+import io.ktor.http.HttpStatusCode
+import io.ktor.response.respond
+import io.ktor.routing.Routing
+import io.ktor.routing.get
+import io.prometheus.client.CollectorRegistry
+import io.prometheus.client.exporter.common.TextFormat
+import io.prometheus.client.hotspot.DefaultExports
+import java.io.StringWriter
 
 fun Routing.metrics(app: SyncApplication) {
     // Register JVM metrics
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/RegistrationModule.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/RegistrationModule.kt
index 1501b243a..2f9d3ef54 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/RegistrationModule.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/RegistrationModule.kt
@@ -19,11 +19,13 @@
 
 package org.isoron.uhabits.sync.app
 
-import io.ktor.application.*
-import io.ktor.http.*
-import io.ktor.response.*
-import io.ktor.routing.*
-import org.isoron.uhabits.sync.*
+import io.ktor.application.call
+import io.ktor.http.HttpStatusCode
+import io.ktor.response.respond
+import io.ktor.routing.Routing
+import io.ktor.routing.post
+import org.isoron.uhabits.sync.RegisterReponse
+import org.isoron.uhabits.sync.ServiceUnavailable
 
 fun Routing.registration(app: SyncApplication) {
     post("/register") {
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/StorageModule.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/StorageModule.kt
index 3e67d359c..aa2689513 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/StorageModule.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/StorageModule.kt
@@ -19,12 +19,18 @@
 
 package org.isoron.uhabits.sync.app
 
-import io.ktor.application.*
-import io.ktor.http.*
-import io.ktor.request.*
-import io.ktor.response.*
-import io.ktor.routing.*
-import org.isoron.uhabits.sync.*
+import io.ktor.application.call
+import io.ktor.http.HttpStatusCode
+import io.ktor.request.receive
+import io.ktor.response.respond
+import io.ktor.routing.Routing
+import io.ktor.routing.get
+import io.ktor.routing.put
+import io.ktor.routing.route
+import org.isoron.uhabits.sync.EditConflictException
+import org.isoron.uhabits.sync.GetDataVersionResponse
+import org.isoron.uhabits.sync.KeyNotFoundException
+import org.isoron.uhabits.sync.SyncData
 
 fun Routing.storage(app: SyncApplication) {
     route("/db/{key}") {
@@ -33,7 +39,7 @@ fun Routing.storage(app: SyncApplication) {
             try {
                 val data = app.server.getData(key)
                 call.respond(HttpStatusCode.OK, data)
-            } catch(e: KeyNotFoundException) {
+            } catch (e: KeyNotFoundException) {
                 call.respond(HttpStatusCode.NotFound)
             }
         }
@@ -54,9 +60,9 @@ fun Routing.storage(app: SyncApplication) {
             try {
                 val version = app.server.getDataVersion(key)
                 call.respond(HttpStatusCode.OK, GetDataVersionResponse(version))
-            } catch(e: KeyNotFoundException) {
+            } catch (e: KeyNotFoundException) {
                 call.respond(HttpStatusCode.NotFound)
             }
         }
     }
-}
\ No newline at end of file
+}
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/SyncApplication.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/SyncApplication.kt
index 1da1f3a71..2e49f15e5 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/SyncApplication.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/app/SyncApplication.kt
@@ -19,13 +19,18 @@
 
 package org.isoron.uhabits.sync.app
 
-import io.ktor.application.*
-import io.ktor.features.*
-import io.ktor.jackson.*
-import io.ktor.routing.*
-import org.isoron.uhabits.sync.repository.*
-import org.isoron.uhabits.sync.server.*
-import java.nio.file.*
+import io.ktor.application.Application
+import io.ktor.application.install
+import io.ktor.features.CallLogging
+import io.ktor.features.ContentNegotiation
+import io.ktor.features.DefaultHeaders
+import io.ktor.jackson.jackson
+import io.ktor.routing.routing
+import org.isoron.uhabits.sync.repository.FileRepository
+import org.isoron.uhabits.sync.server.AbstractSyncServer
+import org.isoron.uhabits.sync.server.RepositorySyncServer
+import java.nio.file.Path
+import java.nio.file.Paths
 
 fun Application.main() = SyncApplication().apply { main() }
 
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/links/LinkManager.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/links/LinkManager.kt
index 4b153861c..db3daf25f 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/links/LinkManager.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/links/LinkManager.kt
@@ -19,8 +19,8 @@
 
 package org.isoron.uhabits.sync.links
 
-import org.isoron.uhabits.sync.*
-import org.isoron.uhabits.sync.utils.*
+import org.isoron.uhabits.sync.KeyNotFoundException
+import org.isoron.uhabits.sync.utils.randomString
 
 class LinkManager(
     private val timeoutInMillis: Long = 900_000,
@@ -46,4 +46,4 @@ class LinkManager(
         }
         return link
     }
-}
\ No newline at end of file
+}
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/repository/FileRepository.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/repository/FileRepository.kt
index 1faf93fc7..72ec57c5b 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/repository/FileRepository.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/repository/FileRepository.kt
@@ -19,9 +19,10 @@
 
 package org.isoron.uhabits.sync.repository
 
-import org.isoron.uhabits.sync.*
-import java.io.*
-import java.nio.file.*
+import org.isoron.uhabits.sync.KeyNotFoundException
+import org.isoron.uhabits.sync.SyncData
+import java.io.PrintWriter
+import java.nio.file.Path
 
 class FileRepository(
     private val basepath: Path,
@@ -70,4 +71,4 @@ class FileRepository(
     private fun String.toDataPath(): Path {
         return basepath.resolve("${this[0]}/${this[1]}/${this[2]}/${this[3]}/$this")
     }
-}
\ No newline at end of file
+}
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/repository/Repository.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/repository/Repository.kt
index 651ca679f..1e9817ad3 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/repository/Repository.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/repository/Repository.kt
@@ -43,4 +43,3 @@ interface Repository {
      */
     suspend fun contains(key: String): Boolean
 }
-
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/server/AbstractSyncServer.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/server/AbstractSyncServer.kt
index bd18c7b30..2c7153f4e 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/server/AbstractSyncServer.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/server/AbstractSyncServer.kt
@@ -19,8 +19,11 @@
 
 package org.isoron.uhabits.sync.server
 
-import org.isoron.uhabits.sync.*
-import org.isoron.uhabits.sync.links.*
+import org.isoron.uhabits.sync.EditConflictException
+import org.isoron.uhabits.sync.KeyNotFoundException
+import org.isoron.uhabits.sync.ServiceUnavailable
+import org.isoron.uhabits.sync.SyncData
+import org.isoron.uhabits.sync.links.Link
 
 interface AbstractSyncServer {
     /**
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/server/RepositorySyncServer.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/server/RepositorySyncServer.kt
index cdde98d91..9dbf0cbe3 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/server/RepositorySyncServer.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/server/RepositorySyncServer.kt
@@ -19,11 +19,14 @@
 
 package org.isoron.uhabits.sync.server
 
-import io.prometheus.client.*
-import org.isoron.uhabits.sync.*
-import org.isoron.uhabits.sync.links.*
-import org.isoron.uhabits.sync.repository.*
-import org.isoron.uhabits.sync.utils.*
+import io.prometheus.client.Counter
+import org.isoron.uhabits.sync.EditConflictException
+import org.isoron.uhabits.sync.KeyNotFoundException
+import org.isoron.uhabits.sync.SyncData
+import org.isoron.uhabits.sync.links.Link
+import org.isoron.uhabits.sync.links.LinkManager
+import org.isoron.uhabits.sync.repository.Repository
+import org.isoron.uhabits.sync.utils.randomString
 
 /**
  * An AbstractSyncServer that stores all data in a [Repository].
diff --git a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/utils/String.kt b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/utils/String.kt
index da043764f..6427b326b 100644
--- a/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/utils/String.kt
+++ b/uhabits-server/src/main/kotlin/org/isoron/uhabits/sync/utils/String.kt
@@ -19,8 +19,8 @@
 
 package org.isoron.uhabits.sync.utils
 
-import java.util.*
-import kotlin.streams.*
+import java.util.Random
+import kotlin.streams.asSequence
 
 fun randomString(length: Long): String {
     val chars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
@@ -28,4 +28,4 @@ fun randomString(length: Long): String {
         .asSequence()
         .map(chars::get)
         .joinToString("")
-}
\ No newline at end of file
+}
diff --git a/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/app/BaseApplicationTest.kt b/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/app/BaseApplicationTest.kt
index 7b5c6d27b..07111720d 100644
--- a/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/app/BaseApplicationTest.kt
+++ b/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/app/BaseApplicationTest.kt
@@ -20,8 +20,8 @@
 package org.isoron.uhabits.sync.app
 
 import com.nhaarman.mockitokotlin2.mock
-import io.ktor.application.*
-import org.isoron.uhabits.sync.server.*
+import io.ktor.application.Application
+import org.isoron.uhabits.sync.server.AbstractSyncServer
 
 open class BaseApplicationTest {
 
diff --git a/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/app/StorageModuleTest.kt b/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/app/StorageModuleTest.kt
index 7609587e0..5d6d69321 100644
--- a/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/app/StorageModuleTest.kt
+++ b/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/app/StorageModuleTest.kt
@@ -21,12 +21,23 @@ package org.isoron.uhabits.sync.app
 
 import com.nhaarman.mockitokotlin2.verify
 import com.nhaarman.mockitokotlin2.whenever
-import io.ktor.http.*
-import io.ktor.server.testing.*
-import kotlinx.coroutines.*
-import org.isoron.uhabits.sync.*
+import io.ktor.http.ContentType
+import io.ktor.http.HttpHeaders
+import io.ktor.http.HttpMethod
+import io.ktor.http.HttpStatusCode
+import io.ktor.server.testing.TestApplicationCall
+import io.ktor.server.testing.TestApplicationEngine
+import io.ktor.server.testing.handleRequest
+import io.ktor.server.testing.setBody
+import io.ktor.server.testing.withTestApplication
+import kotlinx.coroutines.runBlocking
+import org.isoron.uhabits.sync.EditConflictException
+import org.isoron.uhabits.sync.GetDataVersionResponse
+import org.isoron.uhabits.sync.KeyNotFoundException
+import org.isoron.uhabits.sync.SyncData
+import org.isoron.uhabits.sync.toJson
 import org.junit.Test
-import kotlin.test.*
+import kotlin.test.assertEquals
 
 class StorageModuleTest : BaseApplicationTest() {
     private val data1 = SyncData(1, "Hello world")
@@ -64,7 +75,6 @@ class StorageModuleTest : BaseApplicationTest() {
         }
     }
 
-
     @Test
     fun `when put succeeds should return OK`(): Unit = runBlocking {
         withTestApplication(app()) {
diff --git a/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/repository/FileRepositoryTest.kt b/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/repository/FileRepositoryTest.kt
index 53ce3a8c6..589d56b2a 100644
--- a/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/repository/FileRepositoryTest.kt
+++ b/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/repository/FileRepositoryTest.kt
@@ -17,17 +17,18 @@
  * with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-
 @file:Suppress("BlockingMethodInNonBlockingContext")
 
 package org.isoron.uhabits.sync.repository
 
-import kotlinx.coroutines.*
-import org.hamcrest.CoreMatchers.*
-import org.isoron.uhabits.sync.*
-import org.junit.*
-import org.junit.Assert.*
-import java.nio.file.*
+import kotlinx.coroutines.runBlocking
+import org.hamcrest.CoreMatchers.equalTo
+import org.isoron.uhabits.sync.SyncData
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertThat
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import java.nio.file.Files
 
 class FileRepositoryTest {
 
@@ -50,4 +51,4 @@ class FileRepositoryTest {
         val retrieved = repo.get("abcdefg")
         assertThat(retrieved, equalTo(original))
     }
-}
\ No newline at end of file
+}
diff --git a/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/server/RepositorySyncServerTest.kt b/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/server/RepositorySyncServerTest.kt
index ca1576bda..cbe71e027 100644
--- a/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/server/RepositorySyncServerTest.kt
+++ b/uhabits-server/src/test/kotlin/org/isoron/uhabits/sync/server/RepositorySyncServerTest.kt
@@ -19,12 +19,15 @@
 
 package org.isoron.uhabits.sync.server
 
-import kotlinx.coroutines.*
-import org.isoron.uhabits.sync.*
-import org.isoron.uhabits.sync.repository.*
+import kotlinx.coroutines.runBlocking
+import org.isoron.uhabits.sync.EditConflictException
+import org.isoron.uhabits.sync.KeyNotFoundException
+import org.isoron.uhabits.sync.SyncData
+import org.isoron.uhabits.sync.repository.FileRepository
 import org.junit.Test
-import java.nio.file.*
-import kotlin.test.*
+import java.nio.file.Files
+import kotlin.test.assertEquals
+import kotlin.test.assertFailsWith
 
 class RepositorySyncServerTest {
 
@@ -57,4 +60,4 @@ class RepositorySyncServerTest {
             server.put("INVALID", data0)
         }
     }
-}
\ No newline at end of file
+}