AWS Budgets is the service specifically designed for cost management and control. It allows users to set custom budgets for their AWS costs and usage. You can define a specific monetary amount as a monthly spending limit. The service integrates with Amazon Simple Notification Service (SNS) and email to send alerts when actual or forecasted spending exceeds the configured budget thresholds. This directly addresses both of the company's requirements: setting a spending limit and receiving alerts when that limit is reached.

A. Cost Explorer is a tool for visualizing, understanding, and analyzing your AWS cost and usage data over time, not for setting spending limits or alerts.

B. AWS Trusted Advisor provides recommendations to optimize your AWS environment across cost, performance, and security, but it does not set or enforce spending budgets.

C. Service Quotas is used to view and manage the limits on the number of AWS resources you can run in your account, not the monetary cost of those resources.

1. AWS Billing and Cost Management User Guide: "Managing your costs with AWS Budgets." The documentation states

"You can use AWS Budgets to set custom budgets that alert you when your costs or usage exceed (or are forecasted to exceed) your budgeted amount." This directly confirms the service's purpose aligns with the question's requirements.

2. AWS Cost Management User Guide: "Analyzing your costs with AWS Cost Explorer." This guide describes Cost Explorer as "a tool that enables you to view and analyze your costs and usage

" highlighting its function as an analytical tool rather than a budget-setting and alerting mechanism.

3. AWS Trusted Advisor User Guide: "Getting started with AWS Trusted Advisor." The guide explains

"AWS Trusted Advisor is an online tool that provides you real-time guidance to help you provision your resources following AWS best practices

" confirming its role as an advisory service.

4. Cornell University

Cloudify: "AWS Cost Management Tools." This university resource page explains

"AWS Budgets allows you to set custom budgets that alert you when your costs or usage exceed (or are forecasted to exceed) your budgeted amount." This corroborates the function of AWS Budgets in an academic context.

5. Service Quotas User Guide: "What Is Service Quotas?" The documentation states

"Service Quotas is an AWS service that helps you manage your quotas for many AWS services from a central location

" clarifying its focus on resource quantity limits

not monetary spending.