Developing Apps

Version: 1.24.0


Before you begin, make sure you have the following installed on your system:

Step 1: Initializing the deco App

To kickstart your deco App development, run the following command in your terminal:

deno run -A -r

This command will initialize a new deco App project in your current directory. Choose a meaningful name for your app when prompted.

Step 2: Navigate to Your deco App Directory

After the initialization is complete, navigate to your deco App directory using the following command:


Replace $YOUR_APP_NAME with the name you chose for your deco App during initialization.

Step 3: Understanding the mod.ts File

Now, let's take a look at the mod.ts file in your deco App:

import manifest from "./manifest.gen.ts";
import type { Manifest } from "./manifest.gen.ts";
import type { App, AppContext as AC } from "deco/mod.ts";

export interface State {
  url: string;
export type MyApp = App<Manifest, State>;
export default function App(
  state: State,
): MyApp {
  return {

export type AppContext = AC<MyApp>;

The mod.ts file is the heart of your deco App and is written by the developer. In this file, you import the automatically generated manifest and define the State interface, which represents the properties of your app. This is useful, for instance, to get API Keys for an specific services or to allow the user to manage global settings for the app.

The App function is exported and takes the state object as an argument, representing the state of your app. It then returns an object containing the manifest and the defined state. This function is crucial for your app to work correctly.

Lastly, the AppContext type is exported, representing the context of your app and allowing access to the properties defined in mod.ts.

Step 4: Developing Your deco App

Now that you understand the basic structure of your deco App, you can start developing it. Feel free to add more components, such as sections, actions, workflows, or handlers, to enhance the functionality of your app.

Step 5: Building Your deco App

To see your deco App in action, run the following command:

deno task start

This command will start your app and automatically generate the necessary files to make the app usable by any deco site.


Congratulations! You have successfully created and developed your own deco App. You've learned about the mod.ts file, the heart of your app, which allows you to define the manifest and state of your app. Deco Apps provide a powerful way to bundle and share business capabilities, making it easier to maintain and scale your deco projects. Enjoy coding and feel free to explore more deco features to further enhance your apps! 🚀

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