An API for everything we didn't build.

Quick start

Install the typed SDK, drop in your API key, create your first checkout session in under a minute.

# TypeScript / Node
npm install @gfl/sdk

# Python
pip install gfl

Authentication

All requests authenticate with a scoped API key in the Authorization header. Keys are scoped per-brand on multi-brand workspaces and can be restricted to read-only or to specific resources.

curl https://api.growthflowline.com/v1/checkouts \
  -H "Authorization: Bearer gfl_live_…" \
  -H "Content-Type: application/json"

Core resources

The most common things you'll touch.

• Checkouts

  Create, retrieve, expire

• Customers

  CRUD + custom fields

• Orders

  Read, refund, partial refund

• Subscriptions

  CRUD, pause, swap, skip

• Products

  Catalog + variants

• Transactions

  Filter by processor, status, amount

• Brands

  Multi-brand workspace operations

• Webhooks

  Subscribe to events

Webhooks

Every state change emits an event. Sign your endpoint URL with a per-secret HMAC and we'll deliver, retry on failure (exp-backoff up to 24h), and surface the delivery log in your dashboard.

• checkout.completed
• order.refunded
• subscription.renewed
• subscription.failed
• transaction.captured
• customer.created

Errors & rate limits

JSON errors with stable codes (e.g. card_declined, subscription_not_renewable). Defaults: 100 req/s per API key, burst 200. Higher limits on request.

SDKs

• @gfl/sdk TypeScript / Node
• gfl Python
• gfl-go Go
• gfl-ruby Ruby

Uptime & SLA

99.95% measured uptime on all plans. 99.99% contractual SLA on Enterprise with service-credit terms. Live status at status.growthflowline.com.