diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 25d3996..6b9a366 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,5 +1,4 @@
-# This workflow will do a clean install of node dependencies, cache/restore them, build the source code and run tests across different versions of node
-# For more information see: https://github.com/marketplace/actions/setup-node-js-environment
+# @see: https://github.com/marketplace/actions/setup-node-js-environment
 
 name: CI
 
@@ -17,14 +16,14 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node-version: [18.x, 20.x]
-        # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
+        node: [ 20 ]
+    name: Node ${{ matrix.node }}
     steps:
-    - uses: actions/checkout@v3
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v3
-      with:
-        node-version: ${{ matrix.node-version }}
-        # cache: 'npm'
-    - run: npm install --ignore-scripts
-    - run: npm run all
+      - uses: actions/checkout@v4
+      - name: Setup node
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node }}
+      - run: npm version
+      - run: npm install --ignore-scripts
+      - run: npm run all
diff --git a/.gitignore b/.gitignore
index 6b86644..6f27b55 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,3 +11,5 @@ tmp/
 package-lock.json
 yarn.lock
 pnpm-lock.yaml
+
+.env*
\ No newline at end of file
diff --git a/README.md b/README.md
index 9ffbb67..f7ee31b 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 > debug with levels
 
 [![NPM version](https://badge.fury.io/js/debug-level.svg)](https://www.npmjs.com/package/debug-level/)
-[![Build Status](https://github.com/commenthol/debug-level/workflows/CI/badge.svg?branch=main&event=push)](https://github.com/commenthol/debug-level/actions/workflows/ci.yml?query=branch%3Amain)
+[![CI](https://github.com/commenthol/debug-level/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/commenthol/debug-level/actions/workflows/ci.yml)
 
 A universal JavaScript logging/ debugging utility which works in node and
 browsers.  
diff --git a/package.json b/package.json
index 100be40..5b066c2 100644
--- a/package.json
+++ b/package.json
@@ -60,7 +60,6 @@
     "example": "npm run build:example && npm run start:example",
     "changelog": "conv-changelog -i CHANGELOG.md -o",
     "lint": "eslint --ext .js .",
-    "prepublishOnly": "npm run all",
     "readme": "markedpp --github -i README.md -o README.md",
     "start:example": "DEBUG=* node examples/app/server.cjs",
     "test": "mocha",
@@ -79,15 +78,15 @@
     "flatstr": "^1.0.12",
     "map-lru": "^2.0.0",
     "ms": "^2.1.3",
-    "sonic-boom": "^3.8.0"
+    "sonic-boom": "^4.0.1"
   },
   "devDependencies": {
-    "@babel/cli": "^7.23.9",
-    "@babel/core": "^7.24.0",
-    "@babel/preset-env": "^7.24.0",
+    "@babel/cli": "^7.24.8",
+    "@babel/core": "^7.24.9",
+    "@babel/preset-env": "^7.24.8",
     "assert": "^2.1.0",
     "babel-loader": "^9.1.3",
-    "c8": "^9.1.0",
+    "c8": "^10.1.2",
     "conv-changelog": "^1.0.0",
     "eslint": "^8.57.0",
     "eslint-config-standard": "^17.1.0",
@@ -102,13 +101,13 @@
     "karma-sourcemap-loader": "^0.4.0",
     "karma-spec-reporter": "^0.0.36",
     "karma-webpack": "^5.0.1",
-    "mocha": "^10.3.0",
-    "npm-run-all2": "^6.1.2",
-    "rimraf": "^5.0.5",
-    "rollup": "^4.13.0",
-    "sinon": "^17.0.1",
-    "typescript": "^5.4.2",
-    "webpack": "^5.90.3",
+    "mocha": "^10.7.0",
+    "npm-run-all2": "^6.2.2",
+    "rimraf": "^6.0.1",
+    "rollup": "^4.19.0",
+    "sinon": "^18.0.0",
+    "typescript": "^5.5.3",
+    "webpack": "^5.93.0",
     "webpack-cli": "^5.1.4"
   },
   "optionalDependencies": {
diff --git a/src/Format.js b/src/Format.js
index 6f97abf..e27343f 100644
--- a/src/Format.js
+++ b/src/Format.js
@@ -26,13 +26,22 @@ export class Format {
   }
 
   _formatOpts () {
+    /**
+     * @param {any} any
+     * @returns {string}
+     */
+    // @ts-expect-error
+    const stringify = (any) => fastStringify(any, null, this.opts.spaces)
     this.formatOpts = {
-      // @ts-expect-error
-      stringify: (o) => fastStringify(o, null, this.opts.spaces),
+      stringify,
       spaces: this.opts.spaces
     }
   }
 
+  /**
+   * @param  {...any} args
+   * @returns {string}
+   */
   stringify (...args) {
     // @ts-expect-error
     return fastStringify(...args)
diff --git a/src/LogBase.js b/src/LogBase.js
index 1f64caf..be71aab 100644
--- a/src/LogBase.js
+++ b/src/LogBase.js
@@ -13,7 +13,7 @@ const time = {
 }
 
 /**
- * @typedef {import('./utils').Level} Level
+ * @typedef {import('./utils.js').Level} Level
  *
  * @typedef {object} ExtLogBaseOptions
  * @property {Level} [level] log level
diff --git a/src/Sonic.js b/src/Sonic.js
index 8233153..d89063c 100644
--- a/src/Sonic.js
+++ b/src/Sonic.js
@@ -30,6 +30,8 @@ export class Sonic {
 
     const { fd, path } = streamDescriptor(stream)
 
+    /** @type {import('sonic-boom').SonicBoom} */
+    // @ts-expect-error
     this.stream = new SonicBoom({ fd, dest: path, minLength, sync: true })
     this.stream.on('error', filterBrokenPipe.bind(null, this.stream))
 
@@ -90,10 +92,13 @@ export class SonicStreams extends Map {
    * @returns {string}
    */
   static hash (opts) {
-    return 'sonic!' + Object.keys(opts || {})
-      .sort()
-      .map((key) => `${key}:${opts[key]}`)
-      .join('!')
+    return (
+      'sonic!' +
+      Object.keys(opts || {})
+        .sort()
+        .map((key) => `${key}:${opts[key]}`)
+        .join('!')
+    )
   }
 
   /**
diff --git a/src/browser.js b/src/browser.js
index 0c9eaef..0674095 100644
--- a/src/browser.js
+++ b/src/browser.js
@@ -16,8 +16,8 @@ import { wrapConsole } from './wrapConsole.js'
 import { errSerializer } from './serializers/err.js'
 
 /**
- * @typedef {import('./utils').Level} Level
- * @typedef {import('./LogBase').LogBaseOptions} LogBaseOptions
+ * @typedef {import('./utils.js').Level} Level
+ * @typedef {import('./LogBase.js').LogBaseOptions} LogBaseOptions
  *
  * @typedef {object} ExtLogOptionsBrowser
  * @property {string} [url] url to report errors
diff --git a/src/httpLogs.js b/src/httpLogs.js
index d44bffc..260f7ec 100644
--- a/src/httpLogs.js
+++ b/src/httpLogs.js
@@ -40,7 +40,6 @@ export function httpLogs (namespace, opts) {
   }
   options.serializers = {
     ...serializers,
-    // @ts-expect-error
     ...(options.Log.serializers || {}),
     ...(options.serializers || {})
   }
diff --git a/src/index.js b/src/index.js
index 2d48bae..4f18a6c 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,4 +1,4 @@
-/** @typedef {import('./utils').Level} Level */
+/** @typedef {import('./utils.js').Level} Level */
 /** @typedef {import('./node.js').LogOptions & {Log: typeof Log}} LogOptions */
 /** @typedef {import('./node.js').LogOptionWrapConsole} LogOptionWrapConsole */
 /** @typedef {import('./node.js').LogOptionHandleExitEvents} LogOptionHandleExitEvents */
diff --git a/src/node.js b/src/node.js
index c7caa74..3f0aeb1 100644
--- a/src/node.js
+++ b/src/node.js
@@ -17,7 +17,7 @@ import { LogBase } from './LogBase.js'
 import { wrapConsole } from './wrapConsole.js'
 import { wrapDebug } from './wrapDebug.js'
 import { Sonic, sonicStreams } from './Sonic.js'
-import { errSerializer } from './serializers/err.js'
+import { errSerializer } from './serializers/index.js'
 import { Format } from './Format.js'
 
 const env = process.env.NODE_ENV || 'development'
@@ -25,8 +25,8 @@ const isDevEnv = /^dev/.test(env) // anything which starts with dev is seen as d
 
 const EXIT_EVENTS = ['unhandledRejection', 'uncaughtException']
 
-/** @typedef {import('./LogBase').LogBaseOptions} LogBaseOptions */
-/** @typedef {import('./utils').Level} Level */
+/** @typedef {import('./LogBase.js').LogBaseOptions} LogBaseOptions */
+/** @typedef {import('./utils.js').Level} Level */
 /**
  * @typedef {object} ExtLogOptions
  * @property {boolean} [serverinfo] log serverinfo like hostname and pid
@@ -304,6 +304,9 @@ export class Log extends LogBase {
 
 Log.isDevEnv = isDevEnv
 Log.Sonic = Sonic
+Log.serializers = {
+  err: errSerializer
+}
 
 /**
  * @credits pino/lib/tools.js
diff --git a/tsconfig.json b/tsconfig.json
index dd18dc3..319eefc 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,22 +1,21 @@
 {
   "compilerOptions": {
-    "allowSyntheticDefaultImports": true,
     "allowJs": true,
+    "allowSyntheticDefaultImports": true,
     "checkJs": true,
     "declaration": true,
     "declarationDir": "types",
-    "moduleResolution": "node",
+    "emitDeclarationOnly": true, 
+    "module": "nodenext",
+    "moduleResolution": "nodenext",
+    "noEmitOnError": false,
     "noImplicitAny": false,
+    "skipLibCheck": true,
     "strict": true,
-    "module": "esnext",
     "target": "esnext",
-    "emitDeclarationOnly": true, 
-    "noEmitOnError": true
   },
   "include": [
-    "src/*.js",
-    "src/serializers/*.js",
-    "src/ecs/*.js",
+    "src",
   ],
   "exclude": [
     "node_modules",
diff --git a/types/Format.d.ts b/types/Format.d.ts
index 03d5018..06b77a1 100644
--- a/types/Format.d.ts
+++ b/types/Format.d.ts
@@ -14,9 +14,13 @@ export class Format {
     get spaces(): number | undefined;
     _formatOpts(): void;
     formatOpts: {
-        stringify: (o: any) => string;
+        stringify: (any: any) => string;
         spaces: number | undefined;
     } | undefined;
+    /**
+     * @param  {...any} args
+     * @returns {string}
+     */
     stringify(...args: any[]): string;
     /**
      * formats arguments like `util.format`
diff --git a/types/LogBase.d.ts b/types/LogBase.d.ts
index cc54131..bfa9ad4 100644
--- a/types/LogBase.d.ts
+++ b/types/LogBase.d.ts
@@ -1,5 +1,5 @@
 /**
- * @typedef {import('./utils').Level} Level
+ * @typedef {import('./utils.js').Level} Level
  *
  * @typedef {object} ExtLogBaseOptions
  * @property {Level} [level] log level
@@ -67,8 +67,8 @@ export class LogBase {
      */
     protected _log(nlevel: any, fmt: any, args: any): void;
 }
-export type Timestamp = 'epoch' | 'unix' | 'iso';
-export type Level = import('./utils').Level;
+export type Timestamp = "epoch" | "unix" | "iso";
+export type Level = import("./utils.js").Level;
 export type ExtLogBaseOptions = {
     /**
      * log level
@@ -107,6 +107,6 @@ export type ExtLogBaseOptions = {
      */
     serializers?: object;
 };
-export type FormatOption = import('./Format.js').FormatOption;
+export type FormatOption = import("./Format.js").FormatOption;
 export type LogBaseOptions = FormatOption & ExtLogBaseOptions;
 import { Format } from './Format.js';
diff --git a/types/Sonic.d.ts b/types/Sonic.d.ts
index 92f4edd..6316769 100644
--- a/types/Sonic.d.ts
+++ b/types/Sonic.d.ts
@@ -6,7 +6,8 @@ export class Sonic {
     constructor(stream: NodeJS.WriteStream, opts?: SonicOptions);
     _timer: any;
     _timeout: number;
-    stream: SonicBoom;
+    /** @type {import('sonic-boom').SonicBoom} */
+    stream: import("sonic-boom").SonicBoom;
     /**
      * @param {string} data
      * @returns {boolean}
@@ -46,4 +47,3 @@ export type SonicOptions = {
      */
     timeout?: number | undefined;
 };
-import SonicBoom from 'sonic-boom';
diff --git a/types/browser.d.ts b/types/browser.d.ts
index 728d8b1..22caf61 100644
--- a/types/browser.d.ts
+++ b/types/browser.d.ts
@@ -45,7 +45,7 @@ export class Log extends LogBase {
         /**
          * log level
          */
-        level: import("./utils.js").Level;
+        level: import("./LogBase.js").Level;
         /**
          * namespaces for logging
          */
@@ -73,7 +73,7 @@ export class Log extends LogBase {
         /**
          * serializers to be applied on object properties
          */
-        serializers: any;
+        serializers: object;
         /**
          * url to report errors
          */
@@ -127,8 +127,8 @@ export namespace Log {
     }
 }
 export default Log;
-export type Level = import('./utils').Level;
-export type LogBaseOptions = import('./LogBase').LogBaseOptions;
+export type Level = import("./utils.js").Level;
+export type LogBaseOptions = import("./LogBase.js").LogBaseOptions;
 export type ExtLogOptionsBrowser = {
     /**
      * url to report errors
diff --git a/types/ecs/LogEcs.d.ts b/types/ecs/LogEcs.d.ts
index 55941b7..d5e7f7e 100644
--- a/types/ecs/LogEcs.d.ts
+++ b/types/ecs/LogEcs.d.ts
@@ -24,7 +24,7 @@ export namespace LogEcs {
     export { ecsSerializers as serializers };
 }
 export type EcsSerializer = (val: any, escFields: object) => void;
-export type LogOptionsEcs = import('../node.js').LogOptions & {
+export type LogOptionsEcs = import("../node.js").LogOptions & {
     serializers: Record<string, EcsSerializer>;
 };
 import { Log } from '../node.js';
diff --git a/types/httpLogs.d.ts b/types/httpLogs.d.ts
index 8fc8438..6a3f68a 100644
--- a/types/httpLogs.d.ts
+++ b/types/httpLogs.d.ts
@@ -19,9 +19,9 @@
  * @returns {(req: IncomingMessageWithId, res: ServerResponse, next: Function) => void} connect middleware
  */
 export function httpLogs(namespace?: string | undefined, opts?: LogOptionsHttpLog | undefined): (req: IncomingMessageWithId, res: ServerResponse, next: Function) => void;
-export type IncomingMessage = import('node:http').IncomingMessage;
-export type ServerResponse = import('node:http').ServerResponse;
-export type LogOptions = import('./node.js').LogOptions;
+export type IncomingMessage = import("node:http").IncomingMessage;
+export type ServerResponse = import("node:http").ServerResponse;
+export type LogOptions = import("./node.js").LogOptions;
 export type ExtIncomingMessageId = {
     /**
      * request Id
diff --git a/types/index.d.ts b/types/index.d.ts
index f8cc0a8..2c6260d 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -1,14 +1,14 @@
 export default Log;
-export type Level = import('./utils').Level;
-export type LogOptions = import('./node.js').LogOptions & {
+export type Level = import("./utils.js").Level;
+export type LogOptions = import("./node.js").LogOptions & {
     Log: typeof Log;
 };
-export type LogOptionWrapConsole = import('./node.js').LogOptionWrapConsole;
-export type LogOptionHandleExitEvents = import('./node.js').LogOptionHandleExitEvents;
-export type LogOptionsEcs = import('./ecs/LogEcs.js').LogOptionsEcs;
-export type MwLogOption = import('./browserLogs.js').MwLogOption;
-export type LogOptionsHttpLog = import('./httpLogs.js').LogOptionsHttpLog;
-export type IncomingMessageWithId = import('./httpLogs.js').IncomingMessageWithId;
+export type LogOptionWrapConsole = import("./node.js").LogOptionWrapConsole;
+export type LogOptionHandleExitEvents = import("./node.js").LogOptionHandleExitEvents;
+export type LogOptionsEcs = import("./ecs/LogEcs.js").LogOptionsEcs;
+export type MwLogOption = import("./browserLogs.js").MwLogOption;
+export type LogOptionsHttpLog = import("./httpLogs.js").LogOptionsHttpLog;
+export type IncomingMessageWithId = import("./httpLogs.js").IncomingMessageWithId;
 import { Log } from './node.js';
 import { LogEcs } from './ecs/LogEcs.js';
 import { logger } from './logger.js';
diff --git a/types/logger.d.ts b/types/logger.d.ts
index 47bb329..8b5c9c1 100644
--- a/types/logger.d.ts
+++ b/types/logger.d.ts
@@ -6,4 +6,4 @@
  * @param {LogOptions} [opts]
  */
 export function logger(namespace: string, opts?: import("./index.js").LogOptions | undefined): any;
-export type LogOptions = import('./index.js').LogOptions;
+export type LogOptions = import("./index.js").LogOptions;
diff --git a/types/node.d.ts b/types/node.d.ts
index 0b906ef..cac72e6 100644
--- a/types/node.d.ts
+++ b/types/node.d.ts
@@ -79,7 +79,7 @@ export class Log extends LogBase {
         /**
          * serializers to be applied on object properties
          */
-        serializers: any;
+        serializers: object;
         /**
          * log serverinfo like hostname and pid
          */
@@ -136,9 +136,12 @@ export class Log extends LogBase {
 export namespace Log {
     export { isDevEnv };
     export { Sonic };
+    export namespace serializers {
+        export { errSerializer as err };
+    }
 }
-export type LogBaseOptions = import('./LogBase').LogBaseOptions;
-export type Level = import('./utils').Level;
+export type LogBaseOptions = import("./LogBase.js").LogBaseOptions;
+export type Level = import("./utils.js").Level;
 export type ExtLogOptions = {
     /**
      * log serverinfo like hostname and pid
@@ -178,4 +181,5 @@ import { LogBase } from './LogBase.js';
 declare function toJson(obj: object, serializers: object, spaces?: number | undefined): string;
 import { Sonic } from './Sonic.js';
 declare const isDevEnv: boolean;
+import { errSerializer } from './serializers/index.js';
 export {};
diff --git a/types/utils.d.ts b/types/utils.d.ts
index 88baa44..d6fb816 100644
--- a/types/utils.d.ts
+++ b/types/utils.d.ts
@@ -71,4 +71,4 @@ export function inspectNamespaces(obj: any): {
     namespaces: any;
 } | undefined;
 export function random(len: any): string;
-export type Level = 'LOG' | 'FATAL' | 'ERROR' | 'WARN' | 'INFO' | 'DEBUG' | 'TRACE' | 'OFF';
+export type Level = "LOG" | "FATAL" | "ERROR" | "WARN" | "INFO" | "DEBUG" | "TRACE" | "OFF";