Complete API reference for integrating Margin's payment optimization products into your checkout flow.

Getting Started

Margin provides real-time APIs to optimize payment costs at checkout. Integrate our products to: detect high-cost commercial cards, promote lower-cost payment methods, analyze FX markups, optimize refund handling, and prevent interchange downgrades.

Authentication

Authenticate API requests using your API key. Include it in the X-API-Key header:

X-API-Key: sk_live_your_api_key_here

Get your API keys from the API Keys settings page. Most endpoints work without authentication for testing, but require an API key in production for usage tracking and billing.

Available Products

margin/steer

Intelligent steering away from high-cost commercial cards

margin/push

Proactive promotion of SEPA Instant and Open Banking rails

margin/fx

Detection and mitigation of hidden FX markups

margin/back

Minimization of non-recovered interchange on refunds

margin/down

Prevention of interchange downgrades

Base URL

https://margin.so/api

Rate Limits

API requests are rate-limited based on your subscription plan. Free tier accounts are limited to 100 requests per minute. Contact sales for higher limits or upgrade your plan.

API Reference