diff --git a/README.md b/README.md
index 3adfba7..d7b0edc 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,12 @@
 
 Utilities in the I18N package are designed for internationalization of Yandex Cloud UI services.
 
+### Breaking changes in 0.6.0
+
+- Removed static method setDefaultLang, you have to use i18n.setLang instead
+- Removed default Rum Logger, you have to connect your own logger from application side
+- Removed static property LANGS
+
 ### Install
 
 `npm install --save @yandex-cloud/i18n`
@@ -56,12 +62,12 @@ const i18n = new I18N();
 i18n.registerKeysets('ru', ru);
 i18n.registerKeysets('en', en);
 
-I18N.setDefaultLang('ru');
+i18n.setLang('ru');
 console.log(
     i18n.i18n('wizard', 'label_error-widget-no-access')
 ); // -> "Нет доступа к чарту"
 
-I18N.setDefaultLang('en');
+i18n.setLang('en');
 console.log(
     i18n.i18n('wizard', 'label_error-widget-no-access')
 ); // -> "No access to the chart
@@ -73,7 +79,7 @@ console.log(
 ); // -> "No access to the chart"
 
 
-I18N.setDefaultLang('ru');
+i18n.setLang('ru');
 console.log(
     keyset('label_error-widget-no-access')
 ); // -> "Нет доступа к чарту"
@@ -92,7 +98,7 @@ The library supports templating. Templated variables are enclosed in double curl
 
 ```json
 {
-  "label_template": "No matches found for "{{inputValue}}" in "{{folderName}}"
+  "label_template": "No matches found for '{{inputValue}}' in '{{folderName}}'"
 }
 ```
 
diff --git a/src/index.spec.ts b/src/index.spec.ts
index f6b855f..15d5b62 100644
--- a/src/index.spec.ts
+++ b/src/index.spec.ts
@@ -1,4 +1,4 @@
-import {I18N} from "./index";
+import {I18N} from './index';
 
 let i18n: I18N;
 
@@ -42,6 +42,7 @@ describe('has', () => {
 describe('i18n', () => {
     it('should return key when translation missing', () => {
         i18n.setLang('ru');
+        i18n.registerKeyset('ru', 'notification', {});
         expect(i18n.i18n('notification', 'title')).toBe('title');
     });
 
diff --git a/src/index.ts b/src/index.ts
index 95bad7b..83a3985 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,7 +1,7 @@
-import {pluralize} from "./pluralize";
-import {replaceParams} from "./replace-params";
-import {rumLogger} from "./rum-logger";
-import {Logger, Params, Plural} from "./types";
+import {pluralize} from './pluralize';
+import {replaceParams} from './replace-params';
+import {Logger, Params, Plural} from './types';
+
 
 type KeysData = Record<string, string | string[]>;
 type KeysetData = Record<string, KeysData>;
@@ -9,42 +9,16 @@ type KeysetData = Record<string, KeysData>;
 export * from './types';
 
 export class I18N {
-    static LANGS: Record<string, string> = {
-        ru: 'ru',
-        en: 'en',
-    };
-
-    static defaultLang: string | undefined = undefined;
-
-    static setDefaultLang(lang: string) {
-        if (I18N.LANGS[lang]) {
-            I18N.defaultLang = lang;
-        } else {
-            console.warn('Attempted to set unknown lang as default.');
-            I18N.defaultLang = I18N.LANGS.ru;
-        }
-    }
-
-    data: Record<string, KeysetData> = {
-        [I18N.LANGS.ru]: {},
-        [I18N.LANGS.en]: {},
-    };
-
-    lang: string | undefined = undefined;
-
+    data: Record<string, KeysetData> = {};
+    lang?: string = undefined;
     logger: Logger | null = null;
 
-    constructor(options: {logger?: Logger} = {logger: rumLogger}) {
+    constructor(options?: {logger?: Logger}) {
         this.logger = options?.logger || null;
     }
 
     setLang(lang: string) {
-        if (I18N.LANGS[lang]) {
-            this.lang = lang;
-        } else {
-            console.warn('Attempted to set unknown lang.');
-            this.lang = I18N.LANGS.ru;
-        }
+        this.lang = lang;
     }
 
     registerKeyset(lang: string, keysetName: string, data: KeysData = {}) {
@@ -60,28 +34,19 @@ export class I18N {
         });
     }
 
-    has(keysetName: string, key: string) {
-        const lang = this.lang || I18N.defaultLang;
-        let languageData: KeysetData | undefined;
-        if (lang) {
-            languageData = this.data[lang];
-        }
+    has(keysetName: string, key: string, lang?: string) {
+        const languageData = this.getLanguageData(lang);
 
         return Boolean(languageData && languageData[keysetName] && languageData[keysetName][key]);
     }
 
     i18n(keysetName: string, key: string, params?: Params): string {
-        const lang = this.lang || I18N.defaultLang;
-        let languageData: KeysetData | undefined;
-        if (lang) {
-            languageData = this.data[lang];
-        }
+        const languageData = this.getLanguageData(this.lang);
 
         if (typeof languageData === 'undefined') {
-            throw new Error(`Language '${lang}' is not defined, make sure you call setLang for the same language you called registerKeysets for!`);
+            throw new Error(`Language '${this.lang}' is not defined, make sure you call setLang for the same language you called registerKeysets for!`);
         }
 
-        // если нет переводов
         if (Object.keys(languageData).length === 0) {
             this.warn('Language data is empty.');
 
@@ -90,7 +55,6 @@ export class I18N {
 
         const keyset = languageData[keysetName];
 
-        // если нет кейсета
         if (!keyset) {
             this.warn(
                 'Keyset not found.',
@@ -100,7 +64,6 @@ export class I18N {
             return key;
         }
 
-        // если в кейсете нет переводов
         if (Object.keys(keyset).length === 0) {
             this.warn(
                 'Keyset is empty.',
@@ -189,4 +152,9 @@ export class I18N {
             }
         });
     }
+
+    protected getLanguageData(lang?: string): KeysetData | undefined {
+        const langCode = lang || this.lang;
+        return langCode ? this.data[langCode] : undefined;
+    }
 }
diff --git a/src/pluralize.ts b/src/pluralize.ts
index f6574a5..0aec377 100644
--- a/src/pluralize.ts
+++ b/src/pluralize.ts
@@ -1,4 +1,4 @@
-import {Plural} from "./types";
+import {Plural} from './types';
 
 export function pluralize(keyValue: string[], count: number): string {
     let result: string;
diff --git a/src/replace-params.ts b/src/replace-params.ts
index c006b67..3e3d95f 100644
--- a/src/replace-params.ts
+++ b/src/replace-params.ts
@@ -1,4 +1,4 @@
-import {Params} from "./types";
+import {Params} from './types';
 
 export function replaceParams(keyValue: string, params: Params): string {
     let result = keyValue;
diff --git a/src/rum-logger.ts b/src/rum-logger.ts
deleted file mode 100644
index 0e3c2ec..0000000
--- a/src/rum-logger.ts
+++ /dev/null
@@ -1,54 +0,0 @@
-/* eslint camelcase: ['error', {allow: ['__webpack_require__']}] */
-
-import {Logger} from "./types";
-
-declare let __webpack_require__: unknown;
-
-declare global {
-    interface Window {
-        Ya?: {
-            Rum?: {
-                logError: (arg?: any) => void;
-                ERROR_LEVEL: {
-                    INFO: string;
-                };
-            };
-        };
-    }
-}
-
-const warnCache = new Set();
-
-/**
- * @deprecated
- */
-export const rumLogger: Logger = {
-    log(message, {level, logger, extra} = {}) {
-        if (typeof window === 'undefined' || typeof window.Ya?.Rum?.logError !== 'function') {
-            return;
-        }
-
-        if (warnCache.has(logger)) {
-            return;
-        }
-
-        if (typeof __webpack_require__ !== 'undefined' && process.env.NODE_ENV === 'development') {
-            console.warn('@yandex-cloud/i18n: default logger is deprecated, and would be removed in future. Consult docs for alternative.');
-        }
-
-        console.warn(`[${extra?.type}][${logger || ''}] ${message}`);
-
-        try {
-            window.Ya.Rum.logError({
-                message,
-                type: extra?.type,
-                level: level === 'info' ? window.Ya.Rum.ERROR_LEVEL.INFO : undefined,
-                block: logger
-            });
-        } catch (err) {
-            console.error(err);
-        }
-
-        warnCache.add(logger);
-    }
-};