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

# Diameter API Documentation

> The Diameter API lets you onboard end users, manage virtual accounts, and process domestic and international wire payments through partner banks.

The Diameter API is a banking platform that enables fintechs and financial services companies to embed payment capabilities into their products. Through a single REST API, you can onboard individual and organization end users, initiate domestic and international wire transfers, and receive real-time payment status updates via webhooks — all through Diameter's partner bank network.

> [card] [Quick Start](https://diameterpay.mintlify.site/quickstart.md)
>
> Make your first API call in minutes with step-by-step guidance

> [card] [Authentication](https://diameterpay.mintlify.site/authentication.md)
>
> Set up OAuth2 credentials and learn how to obtain access tokens

> [card] [Guides](https://diameterpay.mintlify.site/guides/onboard-end-user.md)
>
> Step-by-step walkthroughs for onboarding users and initiating payments

> [card] [API Reference](https://diameterpay.mintlify.site/api-reference/overview.md)
>
> Full reference for every endpoint, parameter, and response field

## How Diameter Works

Diameter connects your platform to partner banks through a unified API. Once you obtain OAuth2 credentials, you can start onboarding end users and processing payments in a few steps:

**1. Obtain credentials**

Contact [support@diameterpay.com](mailto:support@diameterpay.com) to receive your `client_id` and `client_secret` for sandbox or production.

**2. Get an access token**

Use the OAuth2 Client Credentials flow to exchange your credentials for a short-lived Bearer token.

**3. Onboard an end user**

Create an individual or organization end user. Diameter handles compliance checks and bank onboarding automatically.

**4. Initiate a payment**

Once the end user is active and has a virtual account, create a counterparty and initiate a domestic wire, international wire, or internal transfer.

## Explore by Topic

> [card] [End Users](https://diameterpay.mintlify.site/concepts/end-users.md)
>
> Manage individuals and organizations on the platform

> [card] [Payments](https://diameterpay.mintlify.site/concepts/payments.md)
>
> Domestic wires, international wires, and internal transfers

> [card] [Webhooks](https://diameterpay.mintlify.site/guides/webhooks.md)
>
> Real-time event notifications for payments and user lifecycle

> [card] [Accounts](https://diameterpay.mintlify.site/concepts/accounts.md)
>
> Virtual accounts automatically created during onboarding

> [card] [Counterparties](https://diameterpay.mintlify.site/concepts/counterparties.md)
>
> Register payment recipients to speed up wire processing

> [card] [Sandbox Testing](https://diameterpay.mintlify.site/guides/sandbox-testing.md)
>
> Simulate inbound wires and test your integration end-to-end

## Environments

Diameter provides separate sandbox and production environments. All sandbox operations are isolated and use test data.

| Environment | Base URL | Auth URL |
| - | - | - |
| Sandbox | `https://api.sandbox.diameterpay.com` | `https://auth.sandbox.diameterpay.com` |
| Production | `https://api.prod.diameterpay.com` | `https://auth.prod.diameterpay.com` |

> [!NOTE]
>
> Contact [support@diameterpay.com](mailto:support@diameterpay.com) to request sandbox or production credentials.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.