Payment API Endpoints

The template supports four payment providers: Stripe, Lemon Squeezy, Polar, and Solidgate. Each provider has its own set of API routes for checkout, subscription management, and webhook handling. A generic /api/payment group provides provider-agnostic subscription queries.

Stripe (/api/stripe)

Stripe is the most feature-complete integration with 17 route handlers covering checkout, subscriptions, payment methods, setup intents, and products.

Checkout

Method	Path	Description
POST	/api/stripe/checkout	Create a Stripe Checkout Session

Subscriptions

Method	Path	Description
GET	/api/stripe/subscription	Get current user's active subscription
POST	/api/stripe/subscription	Create a new subscription
GET	/api/stripe/subscriptions	List all user subscriptions
POST	/api/stripe/subscription/[subscriptionId]/cancel	Cancel a subscription
POST	/api/stripe/subscription/[subscriptionId]/reactivate	Reactivate a cancelled subscription
POST	/api/stripe/subscription/[subscriptionId]/update	Update subscription (change plan)
POST	/api/stripe/subscription/portal	Create a Stripe Customer Portal session

Payment Methods

Method	Path	Description
GET	/api/stripe/payment-methods/list	List saved payment methods
POST	/api/stripe/payment-methods/create	Add a new payment method
PUT	/api/stripe/payment-methods/update	Update default payment method
DELETE	/api/stripe/payment-methods/delete	Remove a payment method
GET	/api/stripe/payment-methods/[id]	Get payment method details

Setup Intents

Method	Path	Description
POST	/api/stripe/setup-intent	Create a Setup Intent for saving payment method
GET	/api/stripe/setup-intent/[id]	Get Setup Intent status

Payment Intents

Method	Path	Description
POST	/api/stripe/payment-intent	Create a one-time Payment Intent

Products

Method	Path	Description
GET	/api/stripe/products	List available Stripe products/prices

Webhook

Method	Path	Description
POST	/api/stripe/webhook	Stripe webhook event handler

The Stripe webhook handler processes events such as:

• checkout.session.completed - Checkout completion
• customer.subscription.created - New subscription
• customer.subscription.updated - Subscription changes
• customer.subscription.deleted - Subscription cancellation
• invoice.payment_succeeded - Successful payment
• invoice.payment_failed - Failed payment

Lemon Squeezy (/api/lemonsqueezy)

Lemon Squeezy provides a simpler subscription model with 7 endpoints.

Method	Path	Description
POST	/api/lemonsqueezy/checkout	Create a Lemon Squeezy checkout
GET	/api/lemonsqueezy/list	List user's subscriptions
POST	/api/lemonsqueezy/cancel	Cancel a subscription
POST	/api/lemonsqueezy/reactivate	Reactivate a cancelled subscription
POST	/api/lemonsqueezy/update	Update subscription details
POST	/api/lemonsqueezy/update-plan	Change subscription plan
POST	/api/lemonsqueezy/webhook	Lemon Squeezy webhook handler

Webhook Events

The Lemon Squeezy webhook processes:

• subscription_created - New subscription
• subscription_updated - Plan changes
• subscription_cancelled - Cancellation
• subscription_payment_success - Payment confirmation
• subscription_payment_failed - Payment failure

Polar (/api/polar)

Polar provides 5 endpoints for checkout and subscription management.

Method	Path	Description
POST	/api/polar/checkout	Create a Polar checkout session
POST	/api/polar/subscription/[subscriptionId]/cancel	Cancel subscription
POST	/api/polar/subscription/[subscriptionId]/reactivate	Reactivate subscription
POST	/api/polar/subscription/portal	Access subscription portal
POST	/api/polar/webhook	Polar webhook handler

Solidgate (/api/solidgate)

Solidgate is the most minimal integration with 2 endpoints.

Method	Path	Description
POST	/api/solidgate/checkout	Create a Solidgate checkout
POST	/api/solidgate/webhook	Solidgate webhook handler

Generic Payment (/api/payment)

Provider-agnostic payment endpoints for managing subscriptions regardless of the underlying payment provider.

Method	Path	Description
GET	/api/payment/[subscriptionId]	Get subscription details by ID
GET	/api/payment/account	Get payment account for current user
GET	/api/payment/account/[userId]	Get payment account for specific user (admin)

Webhook Security

All webhook endpoints implement provider-specific signature verification:

Stripe

Stripe webhooks verify the stripe-signature header using the STRIPE_WEBHOOK_SECRET environment variable and the stripe.webhooks.constructEvent() method.

Lemon Squeezy

Lemon Squeezy webhooks verify the x-signature header using HMAC-SHA256 with the LEMONSQUEEZY_WEBHOOK_SECRET.

Polar

Polar webhooks verify request signatures using the POLAR_WEBHOOK_SECRET.

Solidgate

Solidgate webhooks use their SDK's built-in signature verification with the SOLIDGATE_SECRET_KEY.

Environment Variables

Stripe

Variable	Description
STRIPE_SECRET_KEY	Stripe API secret key
STRIPE_PUBLISHABLE_KEY	Stripe publishable key (client-side)
STRIPE_WEBHOOK_SECRET	Webhook signing secret

Lemon Squeezy

Variable	Description
LEMONSQUEEZY_API_KEY	Lemon Squeezy API key
LEMONSQUEEZY_STORE_ID	Store identifier
LEMONSQUEEZY_WEBHOOK_SECRET	Webhook signing secret

Polar

Variable	Description
POLAR_ACCESS_TOKEN	Polar API access token
POLAR_WEBHOOK_SECRET	Webhook signing secret
POLAR_ORGANIZATION_ID	Organization identifier

Solidgate

Variable	Description
SOLIDGATE_MERCHANT_ID	Merchant identifier
SOLIDGATE_SECRET_KEY	API secret key

Authentication Requirements

Endpoint Type	Auth Required
Checkout creation	Yes (authenticated user)
Subscription management	Yes (subscription owner)
Payment method management	Yes (Stripe customer)
Product listing	Public (Stripe products)
Webhook handlers	Signature verification (no session)
Generic payment queries	Yes (account owner or admin)