Billing Portal
Let people manage their own subscription.
What it adds
A billing area where users can see their plan, change payment method, get invoices, and cancel.
What your agent is told to do
4
What your agent is told to do
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Use the payment provider's hosted billing portal if it has one. Do not rebuild card management — it's a PCI liability you don't need.
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Show the current plan, renewal date, and payment method on your own account page.
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Make cancelling possible without emailing support. Dark patterns here generate chargebacks.
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Treat the provider's WEBHOOKS as the source of truth for subscription state, never the browser redirect.
Edge cases it handles
4
Edge cases it handles
4- A user returning from checkout before the webhook lands must not see a wrong plan — handle the gap.
- A failed renewal must downgrade access on a defined schedule, not instantly and not never.
- Cancelling should preserve access until the end of the paid period.
- Webhooks must be signature-verified and idempotent — they retry and arrive out of order.
Definition of done
7
Definition of done
7- Card details are handled entirely by the payment provider.
- Subscription state is driven by verified webhooks, not redirects.
- Webhook handling is idempotent and order-independent.
- Users can cancel without contacting support.
- Cancelled users keep access until the period they paid for ends.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Upgrade Modal
Upgrade Modal
Sell the upgrade at the exact moment someone wants it.
What it does
A focused upsell that appears when a free user reaches for a paid capability.
How it works
- 1 Trigger it at the point of intent — when they click the locked thing — not on a timer or on page load.
- 2 Name the specific feature they just tried to use. A generic pricing modal converts far worse.
- 3 State the price plainly and give one button to upgrade.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/upgrade-modal
Booking Deposits
Booking Deposits
Take a partial payment at booking so the slot is held against a real commitment.
What it does
A deposit charged during booking, tracked against the remaining balance and the cancellation policy.
How it works
- 1 Show the deposit amount, the remaining balance, and the refund terms on the booking screen before payment, not in the confirmation afterwards.
- 2 Hold the slot while payment is in progress, and confirm the booking only once the payment provider reports settlement. Treat an unsettled payment as no booking at all.
- 3 Reuse the app's existing hosted checkout and the callback handling that already confirms payments. Do not add a second payment integration for bookings, and do not confirm on the browser redirect alone, because a user who closes the tab never returns to it.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/booking-deposits
Usage Limits
Usage Limits
Cap what free accounts can do — visibly and fairly.
What it does
Per-plan usage limits, enforced server-side, with the user always able to see where they stand.
How it works
- 1 Define limits per plan in one place. Do not scatter magic numbers through the codebase.
- 2 Enforce on the server at the point of creation. A client-side check is decoration.
- 3 Show current usage BEFORE the user hits the wall — surprise limits feel like a bug.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/usage-limits
How it works
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1
Copy the link
Grab the Markdown instruction URL for this feature.
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2
Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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3
It inspects, then implements
Your agent reads your existing app first, then adds the feature to fit it.
Works with your stack
These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.
Need it tighter than that? Customize the feature and tell it exactly what you're running.