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

# Core Concepts

> Understand how PayNext works: smart routing, workflows, and unified control across processors.

PayNext is a modern payments platform. Connect multiple processors, route payments intelligently, and manage everything from one dashboard—while your code interacts with a single SDK.

## How Payments Work

1. **Your app** creates a client session with customer and plan details
2. **SDK Checkout** collects payment method from customer
3. **PayNext** receives the payment and applies your workflow rules
4. **Workflow** routes to the appropriate processor based on your configuration
5. **Processor** authorizes and settles the payment
6. **PayNext** normalizes the response and sends webhooks

## Why PayNext?

### Business Continuity

Route payments across multiple merchant accounts and processors. Built-in redundancy ensures uninterrupted payment processing even during processor outages or maintenance windows.

### Lower Processing Fees

Connect processors in different regions. Route payments to local processors for lower interchange fees and better acceptance rates.

### Higher Acceptance Rates

A/B test processors to find the best performer. Use failover routing to automatically retry failed payments with a different processor.

### Full Payment Method Coverage

Combine payment methods from multiple processors. Offer cards, digital wallets, and alternative payment methods—all through one checkout.

### Unified Data

One API, one dashboard, one analytics view. Compare processor performance, track payments, and manage customers regardless of which processor handled the transaction.

### No-Code Control

Change routing rules, configure checkout, and optimize payments without developer involvement. Track all changes with version history.

## Key Concepts

### Client Sessions

A secure token that initializes SDK checkout. Create one on your server for each payment:

```json theme={"system"}
{
  "customer": { "email": "customer@example.com" },
  "plan": { "id": "plan_7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d" }
}
```

The session contains customer details, plan (pricing), and options. Pass the session `id` to the SDK as `clientToken`.

### Customers & Payment Methods

PayNext stores customers and their payment methods independently of processors. When a customer pays:

* Customer record created/updated in PayNext
* Payment method tokenized and linked to customer
* Card-based payment methods (cards and digital wallets) are reusable for future charges across any processor

### Plans

All charges reference a plan that defines amount, currency, and billing behavior:

| Plan Type     | Use Case                             |
| ------------- | ------------------------------------ |
| **One-off**   | Single charges (purchases, add-ons)  |
| **Recurring** | Subscription billing at any interval |

Create plans in **Dashboard → Plans** or via API.

### Processors

Payment service providers that actually process payments. PayNext routes to them based on your workflow rules.

Configure processors in **Dashboard → Integrations**. Each processor has its own credentials, but your code stays the same. See [Integrations](/integrations/overview) for supported processors.

### CIT vs MIT

| Type                                                                                                                    | When                                     | How                           |
| ----------------------------------------------------------------------------------------------------------------------- | ---------------------------------------- | ----------------------------- |
| <Tooltip tip="Customer-Initiated Transaction—customer is present and authorizes the payment.">CIT</Tooltip>             | Customer is present (checkout)           | SDK Checkout                  |
| <Tooltip tip="Merchant-Initiated Transaction—recurring or off-session payment without customer presence.">MIT</Tooltip> | Customer not present (renewals, retries) | PayNext handles automatically |

First payment is always CIT. Subscription renewals and background charges are MIT.

## Workflows

No-code rules engine for payment routing. Route payments based on:

* Payment method (cards, wallets, APMs)
* Card details (BIN, issuer, network)
* Geography (customer country, issuer country)
* Amount and currency
* Custom metadata
* Processor

### Failover Routing

If a payment fails with one processor, automatically retry with another:

```
Primary: Processor A
↓ (if declined)
Fallback: Processor B
```

### A/B Testing

Split traffic between processors to benchmark performance:

```
50% → Processor A
50% → Processor B
→ Compare acceptance rates
```

See [Workflows](/guides/platform/workflows) for configuration details.

## Dynamic Checkout

Control which payment methods appear based on customer context:

| Condition        | Example                                               |
| ---------------- | ----------------------------------------------------- |
| Customer country | Show region-specific wallets                          |
| Amount           | Show alternative payment methods for orders over \$50 |
| Device           | Show device-native wallets (iOS/Android)              |
| Metadata         | VIP customers see additional payment options          |

Configure in **Dashboard → Checkout**.

## Unified Analytics

Cross-processor reporting from one dashboard:

* **Acceptance rates** by processor, payment method, country
* **A/B test results** with statistical significance
* **Transaction volume** and trends
* **Decline analysis** with actionable insights