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

# Introduction

> Welcome to the Pier API reference! These docs should help you get started quickly and easily.

## Environments

The Pier API is accessible in two environments:

| Environment | API url                           |
| ----------- | --------------------------------- |
| Sandbox     | `sandbox.pier-finance.com/api`    |
| Production  | `production.pier-finance.com/api` |

The sandbox is designed to mimic the production environment, with a few exceptions. Loan agreements created in the sandbox will have large 'draft' watermarks and funds flows will only occur in production. Sandbox API keys are prefixed with `test_` while production API keys are  prefixed with `prod_`.

## Postman collection

You can fork [our Postman collection](https://elements.getpostman.com/redirect?entityId=14754440-cf96aaa5-d588-4a09-b4a0-66c32b77e33c\&entityType=collection) to immediately start interacting with the API. You’ll need to set two variables to get started:

| Variable     | Description                                                |
| ------------ | ---------------------------------------------------------- |
| `api-secret` | Your API secret                                            |
| `url`        | This should generally be set to `sandbox.pier-finance.com` |

## Authentication

Pier uses basic auth to authenticate API requests. All calls should be made with the `username` field left empty and the `password` field set to your API key. Remember to prefix your API key with a colon.

## Rate limits and retrying API requests

Only 5xx (Server Errors) and 429 (Rate Limits) errors should be retried.

Pier's rate limit is set to 1,000 requests per minute. The limit applies to both the sandbox and production environments. If a rate limit is triggered, we will respond with a 429 status code.

## High-level origination flow

The following diagram outlines how the Pier origination flow works with the Borrower, Application and Loan Agreement resources:

**Pier origination flow**

<Frame>
  ![Organization flow](https://mintlify.s3-us-west-1.amazonaws.com/pier/images/origination-flow.png)
</Frame>