# Insomnia Collection
source: https://developer.mastercard.com/payment-initiation-api/documentation/developer-tools/insomnia-collection/index.md

## Insomnia Collection {#insomnia-collection}

[Insomnia](https://insomnia.rest/) is an open-source API client that developers use to quickly and easily send HTTP requests to Mastercard APIs. API Consultancy and Standards developed an [Insomnia Plugin](https://github.com/Mastercard/insomnia-plugin-mastercard) for handling API authentication.
For the full step-by-step guide, open the [Insomnia Collection guide](https://developer.mastercard.com/platform/documentation/developer-tools/insomnia-collection/).

👉Get the Payment Initiation API Insomnia collection here:
[payment-initiation-insomnia-collection.json](https://static.developer.mastercard.com/content/payment-initiation-api/uploads/payment-initiation-insomnia-collection.json) (55KB)

## Overview {#overview}

The Insomnia guide covers how to set up Mastercard API requests in Insomnia, including plugin installation, workspace import options, environment configuration, and request execution.

## Prerequisites {#prerequisites}

* Access to a Mastercard Developers project with the credentials required by the API you are testing
* Insomnia installed on your machine
* The correct authentication and encryption details for the service you want to call

## What You Will Find {#what-you-will-find}

* Plugin installation options for Insomnia
* Import guidance for collections and workspace templates
* Environment setup for OAuth 1.0a flow
* Practical steps for sending and validating requests in Sandbox and Production