# Configuration

> Merx works out of the box. What you configure is what makes it your shop: your currency, your tax rates, your payment keys.

Everything on the following pages is set in `/site/config/config.php` under the `wagnerwagner.merx.` prefix. The [config options reference](https://merx2.wagnerwagner.de/reference/options/config-options.md) lists every option with its default value.

Start with [currencies](https://merx2.wagnerwagner.de/guide/configuration/currencies.md) and [taxes](https://merx2.wagnerwagner.de/guide/configuration/taxes.md) — they decide what a price means and are used by everything else. [Stripe/PayPal secrets](https://merx2.wagnerwagner.de/guide/configuration/stripe-paypal-secrets.md) connects your payment provider, and [testing and production](https://merx2.wagnerwagner.de/guide/configuration/testing-and-production.md) is what you change last, when the shop goes live.

> [!CAUTION]
> Never commit Stripe or PayPal secrets to a repository. [Stripe/PayPal secrets](https://merx2.wagnerwagner.de/guide/configuration/stripe-paypal-secrets.md) shows where to keep them instead.

## Pages

- [Currencies](https://merx2.wagnerwagner.de/guide/configuration/currencies.md): Merx is very flexible when it comes to displaying different prices in different currencies. You can write your own rules (using PHP) to determine when and how each price is displayed.
- [Taxes](https://merx2.wagnerwagner.de/guide/configuration/taxes.md): Each product names a tax rule, and each tax rule sets a rate: a number like `0.19`, or a PHP function that returns one.
- [Stripe/PayPal secrets](https://merx2.wagnerwagner.de/guide/configuration/stripe-paypal-secrets.md): Set up your PayPal/Stripe keys.
- [Order number](https://merx2.wagnerwagner.de/guide/configuration/order-number.md): Merx creates a sequential number for each order page by default. If you want to create your own order numbers you can do so via the config file.
- [Testing and production](https://merx2.wagnerwagner.de/guide/configuration/testing-and-production.md): What the production switch changes, how to test a payment before you flip it, and what to do when you go live.
- [Stripe webhooks](https://merx2.wagnerwagner.de/guide/configuration/stripe-webhooks.md): Some payment methods like SEPA Direct Debit can take up to 6 business days until the payment is confirmed. Learn how to use webhooks to get notified when the payment is succeeded.
- [Localization](https://merx2.wagnerwagner.de/guide/configuration/localization.md): How to translate Merx’ messages and format prices for your visitors’ language.
- [Starterkit](https://merx2.wagnerwagner.de/guide/configuration/starterkit.md)