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Test Mode

Flowlix provides a fully functional test environment that mirrors the live API. Use test mode to build, debug, and validate your integration before processing real payments.

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How test mode works

Test mode and live mode share the same API endpoint (https://api.flowlix.eu) and the same endpoints. The difference is determined entirely by your API key:
Key prefixModeReal charges?Real card networks?
fl_test_sk_TestNoNo
fl_live_sk_LiveYesYes
When you use a test key:
  • No money moves. Cards are not actually charged.
  • No network calls. Card numbers are validated locally using test card rules.
  • Payments are marked livemode: false in the response.
  • Data is isolated. Test payments do not appear in live payment lists and vice versa.

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Switching between modes

Simply swap the API key. No other code changes are needed: 
# Test mode
curl -X POST https://api.flowlix.eu/v1/payments \
  -H "Authorization: Bearer fl_test_sk_abc123" \
  -H "Content-Type: application/json" \
  -d '{"amount": 1000, "currency": "eur", "card": {...}}'

# Live mode (same code, different key)
curl -X POST https://api.flowlix.eu/v1/payments \
  -H "Authorization: Bearer fl_live_sk_xyz789" \
  -H "Content-Type: application/json" \
  -d '{"amount": 1000, "currency": "eur", "card": {...}}'

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What you can test

Everything works in test mode:
  • Creating payments — Direct API and HPP flows.
  • Retrieving and listing payments — Including pagination and filters.
  • Refunding payments — Full refund flow.
  • Error scenarios — Use special test card numbers to trigger declines, specific errors, and edge cases.
  • Idempotency — Keys work identically in test and live modes.

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Test card numbers

Use specific card numbers to simulate different outcomes. Here are the most common ones:
Card numberBehavior
4242424242424242Always succeeds (Visa)
5555555555554444Always succeeds (Mastercard)
4000000000000002Always declined (generic_decline)
4000000000009995Declined with insufficient_funds
See the full list at Test Cards.

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Best practices

  • Use test mode for all development and staging environments. Only use live keys in production.
  • Automate tests against the API using test card numbers to verify your error handling.
  • Test edge cases — simulate declines, expired cards, and rate limits before going live.
  • Use separate API keys for different environments (dev, staging, CI) to keep test data organized.
  • Clear test data periodically in the Dashboard to keep your test environment clean.

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Going live checklist

Before switching to live mode, verify:
1

Error handling

Your integration handles all error types gracefully (card declines, validation errors, server errors).
2

Idempotency

All payment creation and refund requests include an Idempotency-Key header.
3

Retry logic

Network failures and 5xx errors are retried with exponential backoff.
4

Security

API keys are stored securely and never exposed in client-side code.
5

Amounts

You are sending amounts in minor units (cents), not major units (EUR).