# Extension Payment

> Integrate payment gateways into Chrome extensions. Stripe, Paddle, Lemon Squeezy, Polar, PayPal, and more. Licensing, subscriptions, freemium. Use when: payment, monetize, subscribe, billing, premium.

- **Type:** Skill
- **Install:** `agentstack add skill-quangpl-browser-extension-skills-extension-payment`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [quangpl](https://agentstack.voostack.com/s/quangpl)
- **Installs:** 0
- **Category:** [Web & Browser](https://agentstack.voostack.com/c/web-and-browser)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [quangpl](https://github.com/quangpl)
- **Source:** https://github.com/quangpl/browser-extension-skills/tree/main/skills/extension-payment

## Install

```sh
agentstack add skill-quangpl-browser-extension-skills-extension-payment
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Extension Payment Integration

Integrate payment/subscription into a Chrome extension. Ask user for provider, then fetch docs and implement.

## Workflow (Execute This)

### Step 1: Ask user for payment requirements

Ask the user to confirm:
1. **Payment model**: One-time purchase / Subscription / Freemium / Credits-based
2. **Provider category**: Payment Gateway or Merchant of Record (MoR)?
3. **Preferred provider** (or let us recommend)
4. **Required info**: API keys, product/price IDs, webhook URL

> **Recommend MoR** for solo/indie developers — handles tax, compliance, billing portal. No need to register as a business in every country.

### Step 2: Provider selection guide

| Category | Provider | Best For | Docs |
|----------|----------|----------|------|
| **MoR** | Paddle | SaaS subscriptions, global tax | https://developer.paddle.com |
| **MoR** | Lemon Squeezy | Indie/solo devs, simple setup | https://docs.lemonsqueezy.com |
| **MoR** | Polar | Open source monetization | https://docs.polar.sh |
| **MoR** | Creem | Extension-focused MoR | https://docs.creem.io |
| **MoR** | Dodo Payments | Simple digital products | https://docs.dodopayments.com |
| **MoR** | FastSpring | Enterprise digital commerce | https://developer.fastspring.com |
| **MoR** | Gumroad | Creators, digital products | https://help.gumroad.com |
| **Gateway** | Stripe | Full control, most flexible | https://docs.stripe.com |
| **Gateway** | PayPal | Wide user base, easy checkout | https://developer.paypal.com/docs |
| **Gateway** | Razorpay | India-focused payments | https://razorpay.com/docs |
| **Gateway** | Square | POS + online | https://developer.squareup.com/docs |
| **Gateway** | Adyen | Enterprise, multi-currency | https://docs.adyen.com |
| **Gateway** | Braintree | PayPal-owned, cards + PayPal | https://developer.paypal.com/braintree/docs |
| **Gateway** | Authorize.Net | US legacy, reliable | https://developer.authorize.net |

**llms.txt for AI-assisted docs** (use `docs-seeker` skill):
- Stripe: `https://docs.stripe.com/llms.txt`
- Polar: `https://docs.polar.sh/llms-full.txt`

### Step 3: Fetch provider docs

Use `docs-seeker` skill to fetch the provider's latest API docs. For Stripe/Polar, use llms.txt endpoints.

### Step 4: Implement the integration

See `references/integration-architecture.md` for the full pattern.

**Key architecture** (extensions cannot run backend code):
```
Extension (popup/options) → Your Backend API → Payment Provider
         ↕                        ↕
   chrome.storage          License/subscription DB
```

### Step 5: Show user the post-integration workflow

After integration, show the user this flow:
```
User clicks "Upgrade" in extension
  → Opens payment page (provider-hosted or custom)
  → Completes payment
  → Webhook hits your backend
  → Backend validates + stores license
  → Extension checks license via API
  → Premium features unlocked
```

## References

- `references/integration-architecture.md` — Backend setup, license validation, webhook handling
- `references/mor-vs-gateway.md` — MoR vs Gateway decision guide, tax/compliance
- `references/extension-licensing-patterns.md` — License key, account-based, feature flags
- `references/provider-quickstarts.md` — Quick setup for top 5 providers

## Related Skills

- `extension-publish` — Store submission and listing
- `extension-analyze` — Security audit (API key exposure check)
- `extension-dev` — Feature development workflow

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [quangpl](https://github.com/quangpl)
- **Source:** [quangpl/browser-extension-skills](https://github.com/quangpl/browser-extension-skills)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-quangpl-browser-extension-skills-extension-payment
- Seller: https://agentstack.voostack.com/s/quangpl
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.