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Fynn offers comprehensive developer tools to seamlessly integrate your applications with our platform. Whether you want to automate payment processes, synchronize customer data, or create custom workflows – you’ll find all the necessary resources here.

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Quick Start

API Reference

Complete documentation of all API endpoints with examples.

Create API Key

Generate API keys for authentication.

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Integration Options

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REST API

The Fynn API gives you complete access to all platform features. With the RESTful API you can:
  • Manage customers: Create, update, and retrieve customer data
  • Control subscriptions: Create, modify, and cancel subscriptions
  • Generate invoices: Create, finalize, and send invoices
  • Process payments: Add payment methods and manage transactions
  • Configure products: Manage catalog with products and prices

API Documentation

Learn the API basics and explore all available endpoints.

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Webhooks

Webhooks allow you to react to events in Fynn in real-time. You automatically receive notifications when:
  • A new customer is created
  • A payment is received or fails
  • A subscription is started, changed, or cancelled
  • An invoice is created or paid

Set up Webhooks

Configure webhooks for real-time events.

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OAuth 2.0

For applications that access Fynn on behalf of users, we offer OAuth 2.0 authentication. This enables:
  • Secure user authorization without password sharing
  • Access to user-specific data
  • Single Sign-On (SSO) integration
  • OpenID Connect for identity management

OAuth2 Flow

Implement secure authentication with OAuth 2.0.

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Fynn Functions

With Fynn Functions you can extend the platform logic and implement custom rules:
  • Checkout extensions: Dynamic shipping costs, product options
  • Custom validation: Own business logic in checkout
  • External API integrations: Connection to third-party systems

Fynn Functions

Extend Fynn with custom functions.

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Authentication

All API requests require authentication via API key.
1

Create API key

Go to Settings > API Keys and create a new key.
2

Store key securely

The key is only displayed once. Store it securely.
3

Authenticate requests

Add the key as a Bearer token in the Authorization header:
curl -H "Authorization: Bearer YOUR_API_KEY" \
     https://coreapi.io/v1/customers
Never share your API key publicly. Use environment variables to store keys securely.

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Development Environments

Fynn offers two environments for development:
EnvironmentAPI URLDescription
Productionhttps://coreapi.ioLive environment for production data
Previewhttps://preview.coreapi.ioTest environment for development
Use the Preview environment for testing and development before rolling out changes to production.

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Helpful Resources

n8n Integration

Automate workflows with n8n and Fynn.

Postman Collection

Import the API into Postman for quick testing.

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Support

Need help with integration? Our developer support is available: