diff --git a/infra/azure-functions/src/azure-command.ts b/infra/azure-functions/src/azure-command.ts
index 5ad57c3..958da99 100644
--- a/infra/azure-functions/src/azure-command.ts
+++ b/infra/azure-functions/src/azure-command.ts
@@ -68,7 +68,7 @@ export async function assignRoleAssignment(infraConfig: InfraEnvConfig, options:
 
   const resourceGroup = `rg-nammatham-${resourceName.prefix}`;
   const role = 'Contributor';
-  const assignee = process.env.AZURE_APPLICATION_ID; 
+  const assignee = process.env.AZURE_APPLICATION_ID;
   const scope = `/subscriptions/${process.env.AZURE_SUBSCRIPTION_ID}/resourceGroups/${resourceGroup}`;
   await $`az role assignment create --role ${role} --assignee ${assignee} --scope ${scope}`;
 }
diff --git a/package.json b/package.json
index fc37c36..73948d5 100644
--- a/package.json
+++ b/package.json
@@ -32,6 +32,9 @@
     "type": "git",
     "url": "https://github.com/thaitype/nammatham.git"
   },
+  "peerDependencies": {
+    "tsx": "^4.7.0"
+  },
   "devDependencies": {
     "@inquirer/prompts": "^3.3.0",
     "@types/fs-extra": "^11.0.4",
diff --git a/packages/main/src/command/build/build.ts b/packages/main/src/command/build/build.ts
index db7a763..98fe35a 100644
--- a/packages/main/src/command/build/build.ts
+++ b/packages/main/src/command/build/build.ts
@@ -5,14 +5,11 @@ import { system } from 'pkg-fetch';
 import type { NammathamConfigs } from '../nammatham-config';
 import type { TargetBunOptions, TargetOptions } from './types';
 
-import { createDebugger } from '../utils';
+import { debug } from './internal';
 import { buildExecutableBun } from './bun';
 import { findNearestPackageData } from '../packages';
 import { buildExecutableNodeJs, buildNodeJs } from './nodejs';
 import { constructHostConfig, constructLocalSettings } from '../config';
-
-export const debug = createDebugger('nammatham:build');
-
 /**
  * Hard code the function.json for the SimpleHttpTrigger
  */
@@ -55,7 +52,7 @@ export async function buildRuntime(config: NammathamConfigs) {
 export async function build(config: NammathamConfigs): Promise<void> {
   const targetPath = path.resolve(config.buildPath ?? '.nmt', 'dist');
   fs.mkdirSync(targetPath, { recursive: true });
-  await fs.promises.writeFile(path.join(targetPath, 'host.json'), constructHostConfig(config), 'utf-8');
+  await fs.promises.writeFile(path.join(targetPath, 'host.json'), constructHostConfig(config, 'build'), 'utf-8');
   await fs.promises.writeFile(path.join(targetPath, 'local.settings.json'), constructLocalSettings(), 'utf-8');
 
   if (config.buildOptions?.disabled) {
diff --git a/packages/main/src/command/build/bun.ts b/packages/main/src/command/build/bun.ts
index 0846958..5fe4587 100644
--- a/packages/main/src/command/build/bun.ts
+++ b/packages/main/src/command/build/bun.ts
@@ -4,8 +4,8 @@ import path from 'node:path';
 import type { NammathamConfigs } from '../nammatham-config';
 import type { TargetBunOptions, TargetOptions } from './types';
 
-import { debug, getDistDirectory, getExecutablePath, getPackageInfo } from './build';
-
+import { debug } from './internal';
+import { getDistDirectory, getExecutablePath, getPackageInfo } from './build';
 /**
  * Call bun as a sub-process to build the executable file, for preventing the bundle with tsup
  */
diff --git a/packages/main/src/command/build/internal.ts b/packages/main/src/command/build/internal.ts
new file mode 100644
index 0000000..a7651c1
--- /dev/null
+++ b/packages/main/src/command/build/internal.ts
@@ -0,0 +1,3 @@
+import { createDebugger } from '../utils';
+
+export const debug = createDebugger('nammatham:build');
diff --git a/packages/main/src/command/build/nodejs.ts b/packages/main/src/command/build/nodejs.ts
index b7b92ef..2f41235 100644
--- a/packages/main/src/command/build/nodejs.ts
+++ b/packages/main/src/command/build/nodejs.ts
@@ -6,8 +6,8 @@ import { build as esbuild } from 'esbuild';
 
 import type { NammathamConfigs } from '../nammatham-config';
 
-import { debug, getDistDirectory, getExecutablePath, getPackageInfo } from './build';
-
+import { debug } from './internal';
+import { getDistDirectory, getExecutablePath, getPackageInfo } from './build';
 /**
  * When publish into Azure Functions, the package.json will not be included in the final package.
  * So, it needs to specify the output file manually wheather it is ESM or CommonJS. for example `main.mjs` or `main.cjs`
@@ -69,15 +69,19 @@ export async function buildNodeJs(options: NammathamConfigs): Promise<BuildNodeJ
  */
 export async function buildExecutableNodeJs(options: NammathamConfigs, result: BuildNodeJsResult): Promise<void> {
   if (options.buildOptions?.nodeToolChain?.package !== 'pkg') {
-    throw new Error(`(buildExecutableNodeJs) Unsupported package tool: ${options.buildOptions?.nodeToolChain?.package}`);
+    throw new Error(
+      `(buildExecutableNodeJs) Unsupported package tool: ${options.buildOptions?.nodeToolChain?.package}`
+    );
   }
   const target = options.buildOptions?.target;
-  if(options.runtime !== 'node'){
+  if (options.runtime !== 'node') {
     throw new Error(`(buildExecutableNodeJs) Unsupported runtime: ${options.runtime}`);
   }
   const nodeVersion = options.buildOptions?.nodeToolChain?.version;
-  if(nodeVersion !== 18){
-    throw new Error(`(buildExecutableNodeJs) Only support node.js version 18 due to minimum version of Nammatham Framework.`);
+  if (nodeVersion !== 18) {
+    throw new Error(
+      `(buildExecutableNodeJs) Only support node.js version 18 due to minimum version of Nammatham Framework.`
+    );
   }
   const runtime = options.runtime + nodeVersion;
   if (!target) {
diff --git a/packages/main/src/command/build/types.ts b/packages/main/src/command/build/types.ts
index d52aa8a..1b42050 100644
--- a/packages/main/src/command/build/types.ts
+++ b/packages/main/src/command/build/types.ts
@@ -50,7 +50,7 @@ export interface BuildOptions {
    * Disable the build process. This is useful when you want to disable the build process for a specific environment.
    * You need to manage the build process manually, however, the other Azure Functions configurations will be managed by the framework.
    * For example, `function.json`, `local.settings.json`, and `host.json` will be managed by the framework.
-   * 
+   *
    * @default false
    */
   disabled?: boolean;
diff --git a/packages/main/src/command/cli.ts b/packages/main/src/command/cli.ts
index 1fa9f97..41515cd 100644
--- a/packages/main/src/command/cli.ts
+++ b/packages/main/src/command/cli.ts
@@ -1,17 +1,19 @@
 import { build } from './build';
+import { writeConfig } from './dev';
 import { createDebugger } from './utils';
+import { loadEnvVariables } from './config';
 import { loadConfigFromFile } from './config-loader';
-import { loadEnvVariables, writeConfig } from './config';
 import { startAzureFunctionHost } from './azure-func-host';
 
 const debug = createDebugger('nammatham:cli');
 
 export async function main() {
-  console.log(`Start the command`);
   debug?.(`Working Directory: ${process.cwd()}`);
 
   /**
    * Remove the first two arguments which are the node binary and the script file
+   *
+   * TODO: Use a library like yargs or commander to parse the arguments
    */
   const args = process.argv.slice(2);
   console.log(`Args: ${args}`);
@@ -24,26 +26,13 @@ export async function main() {
   const envVars = loadEnvVariables(config?.envVariablesConfig);
   debug?.(`Loaded env variables: ${JSON.stringify(envVars)}`);
 
+  // debug?.(`Command: ${args[0]}`);
   if (args[0] === 'dev') {
+    debug?.(`Starting dev server`);
     await writeConfig(config, envVars);
-    /**
-     * setup host.json for dev
- 
-      "watchDirectories": [
-          "../src", // Watch the source directory
-          "." // watch the function.json
-        ]
-
-      "defaultExecutablePath": "../node_modules/.bin/tsx",
-      "arguments": [
-        "watch",
-        "../src/main.ts"
-      ]
-     */
+    debug?.(`Config written`);
     await startAzureFunctionHost(config);
   } else if (args[0] === 'build') {
-    console.log(`Build the code`);
     await build(config);
   }
-  console.log(`End the command`);
 }
diff --git a/packages/main/src/command/config-loader/types/host-config.ts b/packages/main/src/command/config-loader/types/host-config.ts
index 1c750ee..4022fdb 100644
--- a/packages/main/src/command/config-loader/types/host-config.ts
+++ b/packages/main/src/command/config-loader/types/host-config.ts
@@ -168,8 +168,8 @@ export interface ExtensionBundle {
   id?: string;
   /**
    * The version range of the bundle to install. The Functions runtime always picks the maximum permissible version defined by the version range or interval.
-   * For example, a version value range of `[4.0.0, 5.0.0)` allows all bundle versions from `4.0.0` up to but not including `5.0.0`. For more information,
-   * see the [interval notation for specifying version ranges](https://learn.microsoft.com/en-us/nuget/reference/package-versioning#version-ranges).
+   * For example, a version value range of `[4.0.0, 5.0.0)` allows all bundle versions from `4.0.0` up to but not including `5.0.0`. For more information,
+   * see the [interval notation for specifying version ranges](https://learn.microsoft.com/en-us/nuget/reference/package-versioning#version-ranges).
    * 
    * The following table lists the currently available version ranges of the default `Microsoft.Azure.Functions.ExtensionBundle` bundles and links to the extensions they include.
    * 
diff --git a/packages/main/src/command/config/config-writer.ts b/packages/main/src/command/config/config-writer.ts
deleted file mode 100644
index 7632339..0000000
--- a/packages/main/src/command/config/config-writer.ts
+++ /dev/null
@@ -1,46 +0,0 @@
-import fs from 'node:fs';
-import path from 'node:path';
-
-import type { EnvVariables } from './load-env-vars';
-import type { LocalSettings, NammathamConfigs } from '../config-loader';
-
-import { getExecutablePath } from '../build';
-
-export async function writeConfig(config: NammathamConfigs, envVars: EnvVariables, tmpPath = '') {
-  const targetPath = path.resolve(config.buildPath ?? './nmt', tmpPath);
-  await Promise.all([
-    fs.promises.writeFile(path.join(targetPath, 'host.json'), constructHostConfig(config), 'utf-8'),
-    fs.promises.writeFile(path.join(targetPath, 'local.settings.json'), constructLocalSettings(envVars), 'utf-8'),
-  ]);
-}
-
-export function constructHostConfig(config: NammathamConfigs): string {
-  return JSON.stringify(
-    {
-      customHandler: {
-        description: {
-          defaultExecutablePath: getExecutablePath(config.buildOptions?.target),
-        },
-        enableForwardingHttpRequest: true,
-      },
-      ...config.hostConfig,
-    },
-    null,
-    2
-  );
-}
-
-export function constructLocalSettings(envVars?: EnvVariables): string {
-  return JSON.stringify(
-    {
-      IsEncrypted: false,
-      Values: {
-        ...envVars,
-        FUNCTIONS_WORKER_RUNTIME: 'custom',
-        AzureWebJobsStorage: envVars?.AzureWebJobsStorage ?? 'UseDevelopmentStorage=true',
-      },
-    } satisfies LocalSettings,
-    null,
-    2
-  );
-}
diff --git a/packages/main/src/command/config/config.ts b/packages/main/src/command/config/config.ts
new file mode 100644
index 0000000..2b363b2
--- /dev/null
+++ b/packages/main/src/command/config/config.ts
@@ -0,0 +1,47 @@
+import type { EnvVariables } from './load-env-vars';
+import type { HostConfigV2, LocalSettings, NammathamConfigs } from '../config-loader';
+
+import { getExecutablePath } from '../build';
+
+export function constructHostConfig(config: NammathamConfigs, mode: 'dev' | 'build'): string {
+  let description: NonNullable<HostConfigV2['customHandler']>['description'] = {};
+  let watchDirectories: HostConfigV2['watchDirectories'];
+  if (mode === 'build') {
+    description = {
+      defaultExecutablePath: getExecutablePath(config.buildOptions?.target),
+    };
+  } else if (mode === 'dev') {
+    description = {
+      defaultExecutablePath: '../node_modules/.bin/tsx',
+      arguments: ['watch', '../src/main.ts'],
+    };
+    watchDirectories = ['../src', '.'];
+  }
+  return JSON.stringify(
+    {
+      customHandler: {
+        description,
+        enableForwardingHttpRequest: true,
+      },
+      watchDirectories,
+      ...config.hostConfig,
+    } as HostConfigV2,
+    null,
+    2
+  );
+}
+
+export function constructLocalSettings(envVars?: EnvVariables): string {
+  return JSON.stringify(
+    {
+      IsEncrypted: false,
+      Values: {
+        ...envVars,
+        FUNCTIONS_WORKER_RUNTIME: 'custom',
+        AzureWebJobsStorage: envVars?.AzureWebJobsStorage ?? 'UseDevelopmentStorage=true',
+      },
+    } satisfies LocalSettings,
+    null,
+    2
+  );
+}
diff --git a/packages/main/src/command/config/index.ts b/packages/main/src/command/config/index.ts
index 84960a6..4b28c87 100644
--- a/packages/main/src/command/config/index.ts
+++ b/packages/main/src/command/config/index.ts
@@ -1,2 +1,2 @@
 export * from './load-env-vars';
-export * from './config-writer';
+export * from './config';
diff --git a/packages/main/src/command/config/load-env-vars.ts b/packages/main/src/command/config/load-env-vars.ts
index c742c0a..8fd9389 100644
--- a/packages/main/src/command/config/load-env-vars.ts
+++ b/packages/main/src/command/config/load-env-vars.ts
@@ -11,7 +11,7 @@ import 'dotenv/config';
 
 export type EnvVariables = Record<string, string | undefined>;
 
-const debug = createDebugger('nammatham:config');
+export const debug = createDebugger('nammatham:config');
 
 export function loadUserDefinedEnvVariables(): EnvVariables {
   for (const envFile of DEFAULT_ENV_FILEs) {
diff --git a/packages/main/src/command/dev/dev.ts b/packages/main/src/command/dev/dev.ts
new file mode 100644
index 0000000..d913afa
--- /dev/null
+++ b/packages/main/src/command/dev/dev.ts
@@ -0,0 +1,25 @@
+import fs from 'node:fs';
+import path from 'node:path';
+
+import type { EnvVariables } from '../config';
+import type { NammathamConfigs } from '../config-loader';
+
+import { createDebugger } from '../utils';
+import { constructHostConfig, constructLocalSettings } from '../config';
+
+const debug = createDebugger('nammatham:dev');
+
+export async function writeConfig(config: NammathamConfigs, envVars: EnvVariables, tmpPath = '') {
+  fs.mkdirSync(path.resolve(config.buildPath ?? './nmt', tmpPath), { recursive: true });
+  const targetPath = path.resolve(config.buildPath ?? './nmt', tmpPath);
+  const result = await Promise.allSettled([
+    fs.promises.writeFile(path.join(targetPath, 'host.json'), constructHostConfig(config, 'dev'), 'utf-8'),
+    fs.promises.writeFile(path.join(targetPath, 'local.settings.json'), constructLocalSettings(envVars), 'utf-8'),
+  ]);
+  result.forEach((r) => {
+    if (r.status === 'rejected') {
+      throw new Error(r.reason);
+    }
+  });
+
+}
diff --git a/packages/main/src/command/dev/index.ts b/packages/main/src/command/dev/index.ts
new file mode 100644
index 0000000..855d466
--- /dev/null
+++ b/packages/main/src/command/dev/index.ts
@@ -0,0 +1 @@
+export * from './dev';
diff --git a/packages/main/src/command/index.ts b/packages/main/src/command/index.ts
index 53a75dc..20dc8a5 100644
--- a/packages/main/src/command/index.ts
+++ b/packages/main/src/command/index.ts
@@ -1,2 +1,3 @@
 export * from './config-loader';
 export * from './build';
+export * from './dev';