diff --git a/src/commonMain/kotlin/com/ioki/lokalise/api/LokaliseClient.kt b/src/commonMain/kotlin/com/ioki/lokalise/api/LokaliseClient.kt
index 5a589bd..92c8564 100644
--- a/src/commonMain/kotlin/com/ioki/lokalise/api/LokaliseClient.kt
+++ b/src/commonMain/kotlin/com/ioki/lokalise/api/LokaliseClient.kt
@@ -1,5 +1,6 @@
 package com.ioki.lokalise.api
 
+import com.ioki.lokalise.api.models.ErrorWrapper
 import com.ioki.lokalise.api.models.FileDownload
 import com.ioki.lokalise.api.models.FileUpload
 import com.ioki.lokalise.api.models.Projects
@@ -16,6 +17,7 @@ import io.ktor.client.request.get
 import io.ktor.client.request.header
 import io.ktor.client.request.post
 import io.ktor.client.request.setBody
+import io.ktor.client.statement.HttpResponse
 import io.ktor.http.ContentType
 import io.ktor.http.contentType
 import io.ktor.serialization.kotlinx.json.json
@@ -39,7 +41,7 @@ interface LokaliseProjects {
      */
     suspend fun allProjects(
         queryParams: Map<String, Any> = emptyMap()
-    ): Projects
+    ): Result<Projects>
 }
 
 interface LokaliseFiles {
@@ -52,7 +54,7 @@ interface LokaliseFiles {
         projectId: String,
         format: String,
         bodyParams: Map<String, Any> = emptyMap()
-    ): FileDownload
+    ): Result<FileDownload>
 
     /**
      * Upload files.
@@ -64,7 +66,7 @@ interface LokaliseFiles {
         filename: String,
         langIso: String,
         bodyParams: Map<String, Any> = emptyMap()
-    ): FileUpload
+    ): Result<FileUpload>
 }
 
 interface LokaliseQueuedProcesses {
@@ -76,7 +78,7 @@ interface LokaliseQueuedProcesses {
     suspend fun retrieveProcess(
         projectId: String,
         processId: String,
-    ): RetrievedProcess
+    ): Result<RetrievedProcess>
 }
 
 /**
@@ -95,7 +97,6 @@ internal fun Lokalise(
     fullLoggingEnabled: Boolean = false,
     httpClientEngine: HttpClientEngine? = null
 ): Lokalise {
-
     val clientConfig: HttpClientConfig<*>.() -> Unit = {
         install(ContentNegotiation) {
             json()
@@ -122,7 +123,7 @@ private class LokaliseClient(
     private val httpClient: HttpClient,
 ) : Lokalise {
 
-    override suspend fun allProjects(queryParams: Map<String, Any>): Projects {
+    override suspend fun allProjects(queryParams: Map<String, Any>): Result<Projects> {
         val requestParams = queryParams
             .map { "${it.key}=${it.value}" }
             .joinToString(separator = "&")
@@ -130,21 +131,21 @@ private class LokaliseClient(
 
         return httpClient
             .get("projects$requestParams")
-            .body()
+            .toResult()
     }
 
     override suspend fun downloadFiles(
         projectId: String,
         format: String,
         bodyParams: Map<String, Any>
-    ): FileDownload {
+    ): Result<FileDownload> {
         val requestBody = bodyParams.toMutableMap()
             .apply { put("format", format) }
             .toRequestBody()
 
         return httpClient
             .post("projects/$projectId/files/download") { setBody(requestBody) }
-            .body()
+            .toResult()
     }
 
     override suspend fun uploadFile(
@@ -153,7 +154,7 @@ private class LokaliseClient(
         filename: String,
         langIso: String,
         bodyParams: Map<String, Any>
-    ): FileUpload {
+    ): Result<FileUpload> {
         val requestBody = bodyParams.toMutableMap()
             .apply {
                 put("data", data)
@@ -164,19 +165,23 @@ private class LokaliseClient(
 
         return httpClient
             .post("projects/$projectId/files/upload") { setBody(requestBody) }
-            .body()
+            .toResult()
     }
 
     override suspend fun retrieveProcess(
         projectId: String,
         processId: String
-    ): RetrievedProcess {
+    ): Result<RetrievedProcess> {
         return httpClient
             .get("projects/$projectId/processes/$processId")
-            .body()
+            .toResult()
     }
 }
 
+private suspend inline fun <reified T> HttpResponse.toResult(): Result<T> =
+    if (status.value in 200..299) Result.Success(body<T>())
+    else Result.Failure(body<ErrorWrapper>().error)
+
 /**
  * Found at
  * [kotlinx.serialization/issues#746](https://github.com/Kotlin/kotlinx.serialization/issues/746#issuecomment-863099397)
diff --git a/src/commonMain/kotlin/com/ioki/lokalise/api/Result.kt b/src/commonMain/kotlin/com/ioki/lokalise/api/Result.kt
new file mode 100644
index 0000000..4f939be
--- /dev/null
+++ b/src/commonMain/kotlin/com/ioki/lokalise/api/Result.kt
@@ -0,0 +1,8 @@
+package com.ioki.lokalise.api
+
+import com.ioki.lokalise.api.models.Error
+
+sealed interface Result<out T> {
+    data class Success<T>(val data: T) : Result<T>
+    data class Failure(val error: Error) : Result<Nothing>
+}
\ No newline at end of file
diff --git a/src/commonMain/kotlin/com/ioki/lokalise/api/models/Error.kt b/src/commonMain/kotlin/com/ioki/lokalise/api/models/Error.kt
new file mode 100644
index 0000000..bfc02f8
--- /dev/null
+++ b/src/commonMain/kotlin/com/ioki/lokalise/api/models/Error.kt
@@ -0,0 +1,15 @@
+package com.ioki.lokalise.api.models
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+internal data class ErrorWrapper(
+    val error: Error,
+)
+
+@Serializable
+data class Error(
+    @SerialName("message") val message: String,
+    @SerialName("code") val code: Int
+)
\ No newline at end of file
diff --git a/src/commonTest/kotlin/com/ioki/lokalise/api/LokaliseClientTest.kt b/src/commonTest/kotlin/com/ioki/lokalise/api/LokaliseClientTest.kt
index ee40d7b..e736d12 100644
--- a/src/commonTest/kotlin/com/ioki/lokalise/api/LokaliseClientTest.kt
+++ b/src/commonTest/kotlin/com/ioki/lokalise/api/LokaliseClientTest.kt
@@ -1,8 +1,9 @@
 package com.ioki.lokalise.api
 
-import com.ioki.lokalise.api.stubs.projectsJson
+import com.ioki.lokalise.api.stubs.errorJson
 import com.ioki.lokalise.api.stubs.fileDownloadJson
 import com.ioki.lokalise.api.stubs.fileUploadJson
+import com.ioki.lokalise.api.stubs.projectsJson
 import com.ioki.lokalise.api.stubs.retrieveProcessJson
 import io.ktor.client.engine.HttpClientEngine
 import io.ktor.client.engine.mock.MockEngine
@@ -11,6 +12,7 @@ import io.ktor.client.engine.mock.toByteArray
 import io.ktor.http.ContentType
 import io.ktor.http.Headers
 import io.ktor.http.HttpMethod
+import io.ktor.http.HttpStatusCode
 import io.ktor.http.headersOf
 import io.ktor.utils.io.core.String
 import kotlinx.coroutines.runBlocking
@@ -20,6 +22,41 @@ import kotlin.test.assertTrue
 
 class LokaliseClientTest {
 
+    @Test
+    fun `test result value with error on allProjects but doesn't matter where`() = runLokaliseTest(
+        errorJson,
+        HttpStatusCode.NotFound
+    ) { lokalise, mockEngine ->
+        val result = lokalise.allProjects()
+
+        assertTrue(result is Result.Failure)
+        assertTrue(result.error.code == 404)
+        assertTrue(result.error.message == "Not Found")
+    }
+
+    @Test
+    fun `test result value without error on allProjects but doesn't matter where`() =
+        runLokaliseTest(projectsJson) { lokalise, mockEngine ->
+            val result = lokalise.allProjects()
+
+            assertTrue(result is Result.Success)
+            assertTrue(result.data.projects.size == 1)
+            with(result.data.projects.first()) {
+                assertEquals(
+                    expected = projectId,
+                    actual = "string"
+                )
+                assertEquals(
+                    expected = createdAtTimestamp,
+                    actual = 0
+                )
+                assertEquals(
+                    expected = settings.branching,
+                    actual = true
+                )
+            }
+        }
+
     @Test
     fun `test list all projects without params`() = runLokaliseTest(projectsJson) { lokalise, mockEngine ->
         lokalise.allProjects()
@@ -211,28 +248,33 @@ class LokaliseClientTest {
             headers.contains("X-Api-Token", "sec3tT0k3n")
     }
 
-    private fun createLokalise(
-        httpClientEngine: HttpClientEngine,
-        token: String = "sec3tT0k3n",
-    ): Lokalise = Lokalise(
-        token = token,
-        fullLoggingEnabled = true,
-        httpClientEngine = httpClientEngine
-    )
-
-    private fun createMockEngine(content: String): MockEngine = MockEngine { _ ->
-        respond(
-            content = content,
-            headers = headersOf("Content-Type", ContentType.Application.Json.toString())
-        )
-    }
-
     private fun runLokaliseTest(
         httpJsonResponse: String,
+        httpStatusCode: HttpStatusCode = HttpStatusCode.OK,
         block: suspend (Lokalise, MockEngine) -> Unit
     ) = runBlocking {
-        val engine = createMockEngine(httpJsonResponse)
+        val engine = createMockEngine(httpJsonResponse, httpStatusCode)
         val lokalise = createLokalise(engine)
         block(lokalise, engine)
     }
 }
+
+private fun createMockEngine(
+    content: String,
+    statusCode: HttpStatusCode
+): MockEngine = MockEngine { _ ->
+    respond(
+        content = content,
+        headers = headersOf("Content-Type", ContentType.Application.Json.toString()),
+        status = statusCode
+    )
+}
+
+private fun createLokalise(
+    httpClientEngine: HttpClientEngine,
+    token: String = "sec3tT0k3n",
+): Lokalise = Lokalise(
+    token = token,
+    fullLoggingEnabled = true,
+    httpClientEngine = httpClientEngine
+)
diff --git a/src/commonTest/kotlin/com/ioki/lokalise/api/stubs/ErrorJson.kt b/src/commonTest/kotlin/com/ioki/lokalise/api/stubs/ErrorJson.kt
new file mode 100644
index 0000000..b97282a
--- /dev/null
+++ b/src/commonTest/kotlin/com/ioki/lokalise/api/stubs/ErrorJson.kt
@@ -0,0 +1,10 @@
+package com.ioki.lokalise.api.stubs
+
+val errorJson = """
+{
+  "error":{
+    "message": "Not Found",
+    "code": 404
+  }
+}
+""".trimIndent()
\ No newline at end of file