> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sundaypyjamas.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Build Your Own AI App

> Optional: create a reusable AI helper. Most everyday work belongs in Agents.

## What is an "app"?

An **app** is an optional custom AI helper you save and reuse. For most day-to-day work on the AI Suite platform — documents, sheets, PDFs, multi-step tasks — use the **[Core Agent](/user-guide/first-agent)** first.

Build an app when you want a dedicated helper with fixed instructions that people open like a mini product.

> The **Core Agent** is your main teammate. An **app** is a specialized notebook that already has instructions on page one.

**Examples of apps people build:**

* A "Customer Reply Writer" that always answers in your brand's friendly tone.
* A "Meeting Notes Summarizer" that turns notes into action items.
* A "Product Q\&A" app that answers from your uploaded product manual.

<Note>
  Prefer something that can also use tools inside the Agents tab? See [Build an Assistant](/user-guide/assistants).
</Note>

## How to build one

<Steps>
  <Step title="Open Apps">
    Click **Apps** in the left menu, then click **New app** (or the create button).

    <Frame caption="The Apps area. Click 'New app' to start building.">
      <img src="https://mintcdn.com/sundaypyjamas/s9bw5Uhxs58-xnp0/images/user-guide/build-app-list.png?fit=max&auto=format&n=s9bw5Uhxs58-xnp0&q=85&s=602c1ba58ae55361e82401aec85afcc4" alt="The Apps section with a list of apps and a create button" width="1440" height="900" data-path="images/user-guide/build-app-list.png" />
    </Frame>
  </Step>

  <Step title="Give it a name">
    Something clear, like *"Customer Reply Writer"*. This is just so you can find it later.
  </Step>

  <Step title="Write its instructions">
    This is the important part. In plain words, tell the app how to behave — its job, its tone, and any rules. For example:

    > *You help our support team reply to customers. Always be warm and friendly. Keep replies under 100 words. Never promise refunds — instead, offer to escalate to a manager.*

    <Tip>
      Think of the instructions as training a new team member on their first day. What would you tell them so they do the job right every time?
    </Tip>
  </Step>

  <Step title="Pick a model">
    Choose the AI brain for your app — see [Choosing a model](/user-guide/choosing-models). The default is a fine starting point.
  </Step>

  <Step title="Add knowledge (optional)">
    Want the app to answer from your documents? Upload them to the app's knowledge area — see [Ask your own documents](/user-guide/knowledge).
  </Step>

  <Step title="Test it in the playground">
    Most apps have a **playground** or **preview** where you can try it out. Send a test message and see how it responds.

    <Frame caption="Testing your app in its playground before sharing it.">
      <img src="https://mintcdn.com/sundaypyjamas/s9bw5Uhxs58-xnp0/images/user-guide/build-app-playground.png?fit=max&auto=format&n=s9bw5Uhxs58-xnp0&q=85&s=e8bd4cef0db59550a3347e33b5bbaaf2" alt="An app playground showing a test conversation" width="1440" height="900" data-path="images/user-guide/build-app-playground.png" />
    </Frame>
  </Step>

  <Step title="Save and use it">
    Happy with it? Save it. Now it's ready whenever you need it — and you can share it with your team.
  </Step>
</Steps>

## Making your app better

* **Refine the instructions.** If it does something you don't like, add a rule about it.
* **Give examples in the instructions.** "Here's an example of a good reply: ..." helps a lot.
* **Add documents** so it answers from real, accurate information.
* **Test with tricky cases** — try the awkward questions your app will really get.

## Next step

<Card title="Connect your tools" icon="plug" href="/user-guide/integrations">
  Let your apps and agents work with tools you already use.
</Card>