diff --git a/eslint.config.ts b/eslint.config.ts
index 754d790..7da81ef 100644
--- a/eslint.config.ts
+++ b/eslint.config.ts
@@ -9,7 +9,12 @@ export default defineConfig([
     files: ['**/*.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
     plugins: {js},
     extends: ['js/recommended'],
-    languageOptions: {globals: {...globals.browser, ...globals.node}}
+    languageOptions: {globals: {...globals.browser, ...globals.node}},
+    rules: {
+      'no-unused-vars': 'warn',
+      '@typescript-eslint/no-unused-vars': ['warn']
+    }
   },
+
   globalIgnores(['dist'])
 ])
diff --git a/package.json b/package.json
index 41832e1..2c9336d 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,9 @@
     "typecheck": "tsc --noEmit"
   },
 
-  "dependencies": {},
+  "dependencies": {
+    "chalk": "^5.6.2"
+  },
   "devDependencies": {
     "@eslint/js": "^9.35.0",
     "@types/bun": "^1.2.21",
diff --git a/src/color.ts b/src/color.ts
new file mode 100644
index 0000000..52ca221
--- /dev/null
+++ b/src/color.ts
@@ -0,0 +1,19 @@
+import {Chalk} from 'chalk'
+import {Level} from './types'
+
+const chalk = new Chalk({level: 2}) // 256 colors
+
+export function get_color(level: Level) {
+  switch (level) {
+    case Level.DEBUG:
+      return chalk.blueBright
+    case Level.TRACE:
+      return chalk.green
+    case Level.INFO:
+      return (str: string) => str
+    case Level.WARNING:
+      return chalk.hex('#FFA500')
+    case Level.ERROR:
+      return chalk.red
+  }
+}
diff --git a/src/index.ts b/src/index.ts
index dbe58b4..1eef0f4 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,5 @@
-export function greet() {
-  console.log('Hello, world!')
-}
+import {Level, type WriterOptions, type Writer} from './types'
+import {Logger, writers, options} from './logger'
+
+export default (namespace: string): Logger => new Logger(namespace)
+export {Logger, Level, type WriterOptions, type Writer, writers, options}
diff --git a/src/logger.ts b/src/logger.ts
new file mode 100644
index 0000000..981f981
--- /dev/null
+++ b/src/logger.ts
@@ -0,0 +1,79 @@
+import {Level, type Options, type Writer} from './types'
+
+export const writers = new Map<string, Writer>()
+export const options: Options = {
+  format: '[$time] $level $namespace :',
+  pad_level: true,
+  verbose: true
+}
+
+export class Logger {
+  constructor(private readonly _namespace: string) {}
+
+  public get namespace(): string {
+    return this._namespace
+  }
+
+  public extend(sub_namespace: string): Logger {
+    return new Logger(`${this.namespace}:${sub_namespace}`)
+  }
+
+  public debug(...data: unknown[]): void {
+    log(data, Level.DEBUG, this._namespace)
+  }
+
+  public trace(...data: unknown[]): void {
+    log(data, Level.TRACE, this._namespace)
+  }
+
+  public info(...data: unknown[]): void {
+    log(data, Level.INFO, this._namespace)
+  }
+
+  public warn(...data: unknown[]): void {
+    log(data, Level.WARNING, this._namespace)
+  }
+
+  public error(...data: unknown[]): void {
+    log(data, Level.ERROR, this._namespace)
+  }
+}
+
+function log(message: unknown[], level: Level, namespace: string): void {
+  if (writers.size === 0) {
+    if (options.verbose) console.log('No writer subscribed, discard message')
+    return
+  }
+
+  // Format header of log
+  const head = options.format.replace('$time', new Date().toISOString()).replace('$namespace', namespace)
+
+  let lvl = get_string(level)
+  if (!options.pad_level) lvl = lvl.trimEnd()
+
+  const head_bw = head.replace('$level', lvl)
+
+  for (const [name, writer] of writers.entries()) {
+    const options = writer.options
+    if (options?.minLevel > level) {
+      if (options.verbose) console.log(`Writer's level is lower, discard message for ${name}`)
+      continue
+    }
+    writer.log(level, head_bw, ...message)
+  }
+}
+
+function get_string(level: Level): string {
+  switch (level) {
+    case Level.DEBUG:
+      return 'DEBUG  '
+    case Level.TRACE:
+      return 'TRACE  '
+    case Level.INFO:
+      return 'INFO   '
+    case Level.WARNING:
+      return 'WARNING'
+    case Level.ERROR:
+      return 'ERROR  '
+  }
+}
diff --git a/src/types.ts b/src/types.ts
new file mode 100644
index 0000000..2e1fa6d
--- /dev/null
+++ b/src/types.ts
@@ -0,0 +1,29 @@
+/**
+ * Global options for loggers
+ *
+ * Format : can contain $time, $level and $namespace
+ */
+export type Options = {
+  format: string
+  pad_level: boolean
+  verbose: boolean
+}
+
+export enum Level {
+  TRACE = 0,
+  DEBUG = 1,
+  INFO = 2,
+  WARNING = 3,
+  ERROR = 4
+}
+
+export type WriterOptions = {
+  minLevel: Level
+  [key: string | number | symbol]: unknown
+}
+
+export interface Writer {
+  log(level: Level, ...data: unknown[]): void
+  get options(): WriterOptions
+  readonly _options: WriterOptions
+}