> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mnai.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> API reference for the Realtime Collections API, including base URLs, credentials, and authentication requirements.

<Tip>
  All API calls must be made from your backend. Client applications must never call Meridian APIs directly.
</Tip>

## Request flow

Every payment link is created against a short-lived session. Call [Create a Session](/products/realtime-collections/api-reference/sessions/create-session) to obtain a `sessionKey`, then pass that key in the body of [Create a Payment Link](/products/realtime-collections/api-reference/payment-links/create-payment-link). Session keys expire after 15 minutes and are tied to the operator details supplied when they were issued, so obtain a new key if those details change.

## Base URLs

| Environment | URL                                                   | Purpose                   |
| :---------- | :---------------------------------------------------- | :------------------------ |
| Sandbox     | `https://us-merchant.sandbox.api-us.meridianapps.dev` | Testing and certification |
| Production  | `https://us-merchant.api-us.payments.meridianpay.com` | Live traffic              |

Meridian provides your credentials and endpoint access for the Sandbox environment during onboarding. Always validate your integration against Sandbox before requesting production access.

## Example credentials

| Credential         | Sandbox                              | Production                           |
| ------------------ | ------------------------------------ | ------------------------------------ |
| API Key            | `akey_test_uzbz2fpfswgx22mjjrysljad` | `akey_live_7785ul8u9ymalmpftq311xqw` |
| API Secret         | `asec_test_4zxavmk5iomub4nfm3odynd0` | `asec_live_w69ob7claqhdkw4uo183yl74` |
| Webhook API Key    | `wkey_test_wtr8lqsjaecr4e2h8f0hb58f` | `wkey_live_1m3wfbs0p1m1v09mjff3vd54` |
| Webhook API Secret | `wsec_test_glimkmggzki3mzj1tgml054u` | `wsec_live_ntvxqrmq1t9t546p9zaehop0` |