> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://amer.developers.trustly.com/integrate/core-concepts/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://amer.developers.trustly.com/_mcp/server.

# Core concepts

Before building your integration, familiarize yourself with the core building blocks — from the `establishData` object that configures every transaction to the webhook events that drive your backend logic.

## The basics

#### [Key concepts](/integrate/core-concepts/key-concepts)

The A2A payment model, Trustly Lightbox, and transaction lifecycle.

#### [The \`establishData\` object](/integrate/core-concepts/the-establish-data-object)

Configure merchant credentials, transaction details, and customer data.

## Frontend and UX

#### [Frontend integration](/integrate/core-concepts/integrate-client-sdk)

Understand the client-server boundary, request signatures, and transaction handoff.

#### [Redirect URLs](/integrate/core-concepts/redirect-urls-and-return-flow)

Configure return and cancel URLs for user redirects.

#### [Content strings](/integrate/core-concepts/content-strings)

Trustly-provided UI strings for product names and messaging.

## Backend and security

#### [Transactions and transaction IDs](/integrate/core-concepts/transactions-and-transaction-ids)

How transaction IDs track authorizations and payment events.

#### [Webhooks and events](/integrate/core-concepts/webhooks-and-events)

Receive asynchronous transaction status updates.

#### [Tokens and account security](/integrate/core-concepts/tokens-and-account-security)

Tokenized bank account information and stored credential security.

> Foundational components, data models, and security patterns that power Trustly integrations.

## Docs

- [Key concepts](https://amer.developers.trustly.com/integrate/core-concepts/key-concepts.md)
- [Frontend integration](https://amer.developers.trustly.com/integrate/core-concepts/integrate-client-sdk.md): Understand the client-server boundary, request signatures, and establishData payload.
- [The `establishData` Object](https://amer.developers.trustly.com/integrate/core-concepts/the-establish-data-object.md)
- [Transaction ID](https://amer.developers.trustly.com/integrate/core-concepts/transactions-and-transaction-ids.md)
- [Tokens and account security](https://amer.developers.trustly.com/integrate/core-concepts/tokens-and-account-security.md)
- [Redirect URLs](https://amer.developers.trustly.com/integrate/core-concepts/redirect-urls-and-return-flow.md)
- [Webhooks and events](https://amer.developers.trustly.com/integrate/core-concepts/webhooks-and-events.md): Learn about Trustly event notifications (webhooks) and client-side event listeners
- [Content strings](https://amer.developers.trustly.com/integrate/core-concepts/content-strings.md)