# Introduction to testing tools

**The Sandbox testing suite - everything you need to exercise your integration before real customers do.**

In Sandbox, every part of the payment pipeline you don't control is replaced by a testable stand-in: real cards become [test cards](/docs/guides/merchant/test-and-go-live/testing/test-cards.md), and the bank's 3DS challenge page becomes the [3DS simulator](/docs/guides/merchant/test-and-go-live/testing/3ds-simulator.md). Walk the [checkout flows](/docs/guides/merchant/test-and-go-live/testing/test-flows.md) as your customers will experience them, then finish with the [core test scenarios](/docs/guides/merchant/test-and-go-live/testing/sandbox-test-scenarios.md) - order, refund, and webhook - that every backend should handle.

Everything here assumes your integration is pointed at [Sandbox](/docs/guides/merchant/test-and-go-live/set-up-test-environment#point-integration-at-sandbox).

- [:Card: Test cards](/docs/guides/merchant/test-and-go-live/testing/test-cards.md 'The full list of Sandbox test cards and their outcomes')
- [:CardSecurity: 3DS simulator](/docs/guides/merchant/test-and-go-live/testing/3ds-simulator.md 'How the simulated 3DS challenge page works and how to complete or automate it')

[//]: # 'break'

- [:Timeline: Test payment flows](/docs/guides/merchant/test-and-go-live/testing/test-flows.md 'Walk through checkout flows in Sandbox - payment links, Revolut Pay, and Google Pay')
- [:Questionnaire: Sandbox test scenarios](/docs/guides/merchant/test-and-go-live/testing/sandbox-test-scenarios.md 'The order, refund, and webhook scenarios every backend should handle')