How to build an app for ChatGPT? Step by step guide
The easiest way to build an app for ChatGPT is Yavio. You assemble inputs, logic, and an in chat user interface, then publish with and use it inside ChatGPT.
A ChatGPT app is a callable tool with defined inputs, clear outputs, and an user interface that renders inside the chat.
Key points
- Create an app and at least one tool
- Define inputs, logic, and outputs
- Design the UI element
- Preview, publish, and connect to ChatGPT
- Add auth, secrets, and analyze runs
What do I need before I begin?
You need a Yavio account and access to ChatGPT. Sign up, confirm the email code, and log in to reach the onboarding screen: https://yavio.io
How do I create my first app for ChatGPT?
Click on "Create a new app", then add your first tool. Name the app and the tool. One app can have multiple tools such as hotel search or flight search.
How do I define the tool input?
Open the tool editor and add an input node. Choose simple types like text, email, phone, number, or use custom objects with nested fields. For a hotel search, a text location is enough to start.
How do I add the core logic?
Use one of two paths:
- Edit data node. Add or transform data. For quick demos, paste mock JSON such as a list of hotels with name, style, and image fields.
- API call node. Configure method, URL, headers, and body. Link secrets from workspace settings for keys.
How do I define the tool output correctly?
Run the tool once with sample input such as Lisbon. Open the output node and click generate from last run to infer the output schema. Remove unneeded fields. Run again to confirm a clean execution.
How do I add a user interface to the app for ChatGPT?
Add a UI node. Pick an inline card for a single item or an inline carousel to show many items side by side. Use the drag and drop UI editor to add text, key value, badges, images, buttons, or custom HTML that renders in an iframe. Bind each UI field to tool output fields such as hotel name, style, description, and image URL.
When should I use a carousel instead of a card?
Use a carousel when your output is an array. Set the carousel to dynamic and bind it to the list so the number of items matches the data length. Save and preview to see multiple items rendered.
How do I preview and test the app?
Use the preview screen to run different inputs and see UI updates. With mock data the output is stable, which helps you refine the layout and bindings before going live.
How do I publish the app for ChatGPT?
Open the app overview and go to Publish. Choose what to publish, toggle authentication if needed, and copy the custom app URL. Follow the on screen tutorial to add the app to ChatGPT. You can also connect to Claude.
How do I add authentication and manage secrets?
Enable auth for the tool in the publish screen to require a token. Store API keys as workspace secrets and link them to API call nodes to avoid exposing credentials.
How do I analyze usage and iterate?
Use Analyze to view executions and confirm calls from ChatGPT. Keep refining inputs, logic, and UI as you learn from runs. Billing and credits live in workspace settings along with plan and invoices.
How can I build an app for ChatGPT step by step?
- Create app and tool
- Add input for user intent
- Add logic with mock data or real API
- Run once and generate output schema
- Build an inline card or carousel and bind fields
- Preview and adjust
- Publish, copy the URL, and connect to ChatGPT
- Turn on auth and secrets if needed
- Analyze executions and improve
Try Yavio to build your own app inside ChatGPT in minutes.