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Flowlix Payments API

Flowlix is a modern payment processing platform built for European merchants. Our API follows industry-standard conventions so you can integrate quickly and confidently.

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What you can do

Direct API Payments

Charge cards directly from your backend with full control over the payment flow.

Hosted Payment Page

Redirect customers to a Flowlix-hosted page — no PCI burden on your side.

Refunds

Issue full refunds on any successful payment with a single API call.

Test Mode

Build and test your integration without moving real money.

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API design principles

The Flowlix API is designed to feel immediately familiar to any developer who has integrated a payment API:
  • RESTful — Standard HTTP methods, predictable URL structure, JSON bodies.
  • Bearer token auth — Simple Authorization: Bearer sk_... header.
  • Idempotency — Safely retry any write request with an Idempotency-Key header.
  • Cursor pagination — Efficiently page through large result sets with starting_after / ending_before.
  • Minor units — All amounts are in the smallest currency unit (e.g., cents for EUR).
  • Consistent errors — Structured error objects with type, code, message, and decline_code fields.

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Base URL

All API requests go to: 
https://api.flowlix.eu/v1

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Authentication

Every request must include a valid API key in the Authorization header: 
curl https://api.flowlix.eu/v1/payments \
  -H "Authorization: Bearer fl_test_sk_abc123def456"
There are two types of keys:
PrefixEnvironmentReal charges?
fl_test_sk_Test modeNo
fl_live_sk_Live modeYes
See Authentication for details.

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Next steps

Quickstart

Make your first payment in under 5 minutes.