GPT Billing API Template

Add billing/auth to your OpenAI GPT

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Features

A starter template to write Fastify APIs for OpenAI GPTs with auth, billing and OpenAPI spec generation.

• OAuth authentication with Clerk
• Stripe billing
• Prisma/SQLite for persistence
• 100% TypeScript
• Deploy wherever you like (we use Render)

Getting Started

npm i
npm run dev

Clerk Setup

1. Make a Clerk application
2. Get your publishable key and expose it as CLERK_PUBLISHABLE_KEY
3. Get your secret key and expose it as CLERK_SECRET_KEY
4. Make a Clerk webhook
   1. Point it to the route /webhooks/clerk in this API wherever you've deployed it
   2. Subscribe to the user.created event
5. Expose the webhook signing secret as CLERK_WEBHOOK_SECRET
6. Add a custom domain to your Clerk application that matches the SERVER_URL in your environment variables, which is where you have deployed this API

Clerk OAuth Setup

The app uses Clerk to provide oauth for you GPT.

Run the following to create a Clerk oauth server on your production account:

npm run clerk-oauth-create

This will write the file ./clerk_oauth.json. Use these parameters in the GPT UI to create your oauth login for your GPT.

OpenAI will then generate a callback URL for your GPT, copy this from the UI and run the following script to update your Clerk oauth to use it:

npm run clerk-oauth-update https://chat.openai.com/aip/g-123/oauth/callback

Note you must use a production Clerk account with a custom domain, as the domain of your oauth must match that in your actions openapi spec.

Stripe Setup

1. Get an API key from Stripe: https://dashboard.stripe.com/apikeys
2. Expose it as the env variable STRIPE_SECRET_KEY
3. Make a subscription product in the Stripe UI: https://dashboard.stripe.com/products/create
4. Get the resulting price ID and expose it as STRIPE_PRICE_ID
5. Make a webhook: https://dashboard.stripe.com/webhooks/create
   1. Point it to the route /webhooks/stripe in this API wherever you've deployed it
   2. Make it handle the following events:
      • checkout.session.completed
      • customer.subscription.updated
      • customer.subscription.deleted
6. Obtain the signing secret for your webhook and expose it as STRIPE_WEBHOOK_SECRET

By default, protected API routes will require a subscription after 7 days. Change this by editing TRIAL_DAYS in src/constants.ts or by setting the TRIAL DAYS environment variable.

Other Environment Variables

SERVER_URL should point to wherever you've deployed this API, e.g. https://example.com/api.

DATABASE_URL should point to wherever your database is. You will also need to update the prisma.schema file to use whatever database you have chosen, if it is not SQLite.

GPT_URL should point to your GPT. It is used for redirection from billing pages.

GPT configuration

Point your GPT actions at the route /docs/json wherever you have deployed this API.

If you want to set x-openai-isConsequential for any routes, you will instead need to copy the JSON at /docs/json, manually alter it, and put the resulting spec into your GPT actions.

Tell your GPT about the billing in your instructions (aka prompt), for example:

After a user signs in via OAuth, check their billing subscription status and inform them about the 7-day free trial for this service and display any generated links from actions.

Our GPTs

Built using this backend template.

Database Builder

• Create and Execute Database Migrations: I can help you create and execute database migrations to update the structure of your PostgreSQL database. This includes adding tables, modifying columns, creating indexes, and more.
• Rollback Migrations: If a recent migration didn't go as planned, I can help you roll it back to the previous state.
• Retrieve Current Database Schema: I can fetch and display the current schema of your database, allowing you to see the structure of your tables, columns, and relationships.
• Execute SQL Statements: You can ask me to execute specific SQL statements on your database. This is useful for querying data, updating records, deleting entries, and other database operations.
• Provide Database URL: If you need to connect to the database using external tools or applications, I can provide you with the database URL.
• Check Billing Subscription Status: After you sign in via OAuth, I will check your billing subscription status. I'll inform you about the 7-day free trial for this service and provide any necessary links for subscription management or purchase.