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

# Gateway API

> Access and manage a unified USDC balance across multiple blockchains with instant transfers in under 500 ms.

Gateway is permissionless and built around non-custodial Gateway Wallet
contracts on each supported blockchain. Deposit once, then call the API from
your app.

## Get started

<CardGroup cols={2}>
  <Card title="Gateway documentation" icon="book" href="/gateway">
    Learn how Circle Gateway works.
  </Card>

  <Card title="Supported blockchains" icon="link" href="/gateway/references/supported-blockchains">
    See which blockchains Gateway supports.
  </Card>

  <Card title="Webhooks" icon="bell" href="/api-reference/gateway/all/get-permissionless-subscriptions">
    Set up permissionless webhook subscriptions.
  </Card>
</CardGroup>

## Endpoint categories

<CardGroup cols={2}>
  <Card title="Gateway" icon="dungeon" href="/api-reference/gateway/all/get-token-balances">
    Read balances, request attestations, and inspect transfers.
  </Card>

  <Card title="Gateway Batch" icon="layer-group" href="/api-reference/gateway/all/submit-batch-authorization">
    Submit batched transfer authorizations.
  </Card>

  <Card title="Gateway x402" icon="receipt" href="/api-reference/gateway/all/settle-x402payment">
    Settle and verify x402 payments.
  </Card>
</CardGroup>

## OpenAPI specifications

The Gateway API reference is generated from this OpenAPI specification:

* `https://developers.circle.com/openapi/gateway.yaml`

See [OpenAPI Specifications](/api-reference/openapi-specifications) for the full
catalog of Circle's API specs.