> ## Documentation Index
> Fetch the complete documentation index at: https://docs.sezzle.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Mobile SDKs
Integrate Sezzle directly into your native iOS and Android apps. The Sezzle Mobile SDKs provide two core features:
1. **Promotional Messaging** — drop-in widgets that show installment pricing on product pages
2. **Checkout** — launch a Sezzle checkout session from your app and handle the result
Swift Package Manager, CocoaPods. iOS 15+.
Maven Central, Gradle. Android 6.0+ (API 23).
## How It Works
```mermaid theme={"system"}
sequenceDiagram
participant App as Merchant App
participant SDK as Sezzle SDK
participant API as Sezzle API
participant Browser as Browser / WebView
App->>SDK: 1. Configure (public key)
App->>SDK: 2. Show promotional widget (price)
SDK-->>App: Renders installment messaging
App->>SDK: 3. Start checkout (order details)
SDK->>API: POST /v2/session
API-->>SDK: Session + checkout URL
SDK->>Browser: 4. Open checkout
Browser-->>SDK: 5. Customer completes / cancels
SDK-->>App: 6. Callback (order UUID)
App->>API: 7. Capture payment (server-side)
```
**Server-driven integration?** If you'd rather keep your public key off-device and have your backend create the Sezzle session directly, the SDK also exposes a pass-URL `startCheckout` overload (`1.2.0`+). Your server creates the session, your app hands the resulting `checkout_url` to the SDK, and the SDK reports back via the same delegate. See the **Server-Driven Integration** section in the [iOS](/docs/guides/mobile/ios#8-server-driven-integration) or [Android](/docs/guides/mobile/android#8-server-driven-integration) guide.
## Checkout Modes
The SDK supports two ways to present the Sezzle checkout:
| | System Browser | WebView |
| ------------------- | --------------------------------------------------------------------------- | ---------------------------------- |
| **How it opens** | iOS: `ASWebAuthenticationSession` / Android: Chrome Custom Tab | In-app WKWebView / Android WebView |
| **Recommended** | Yes (default) | Opt-in |
| **Security** | Runs in a separate browser process | Runs inside your app's process |
| **Cookie sharing** | Shares cookies with Safari/Chrome (faster login for returning Sezzle users) | No cookie sharing |
| **User experience** | Brief context switch to browser | Stays inside your app |
## Promotional Messaging
The SDK includes a drop-in promotional widget that automatically displays the right installment messaging based on the product price:
| Price Range | Message |
| --------------------------------------------- | -------------------------------------------------- |
| Below minimum (\$35 default) | Widget hidden |
| $35 -- $49.99 | "or 4 payments of \$X.XX with Sezzle" |
| $50 -- $2,500 | "or 5 payments of \$X.XX with Sezzle" |
| Above short-term max (with long-term enabled) | "or monthly payments as low as \$X.XX with Sezzle" |
Tapping the widget opens an educational modal showing the full payment schedule:
## Dark Mode
Both SDKs automatically adapt to the device's appearance setting. The promotional widget, installment modal, and all brand colors adjust for light and dark mode.
## Prerequisites
Before you begin, make sure you have:
1. A Sezzle merchant account — sign up here if you don't have one
2. Your Public API Key from the Sezzle Merchant Dashboard
3. A backend server that can call the Sezzle API to capture payments after checkout
The SDK uses your **public** API key only. Your private key stays on your server and is used to capture payments after the customer completes checkout.
## Source Code
Both SDKs are open source on GitHub:
* sezzle/sezzle-merchant-sdk-ios
* sezzle/sezzle-merchant-sdk-android