Understanding some API Operations in IoT Core Billing

Hi,

You can find additional details on meter and cost for IoT Core operations here. Some additional content to your two points:

1. HTTP.Response - I'm struggling to understand what this bill represents. Is this responses from http endpoints hit by message routing rules?

Yes, this would be metered responses for negative (400 and 500) responses:

If HTTP responses with HTTP response codes in the 4xx and 5xx range contains a body, AWS IoT Core meters the number of 5 KB message needed to encode the response body

And for your second API Operation question:

2. MQTT.Receive - is this a charge for clients receiving mqtt messages? Are we also charged for messages received by the message routing rules?

Messages sent and received by an MQTT client are metered (see the section in the above link under MQTT Message Metering). The primary ones will be MQTT PUBLISH, which can be from a device publishing to IoT Core, or from IoT Core (service) publishing out to a device.

As Rick also mentioned, you can open a support case for additional insights into your specific account costs. It's also good to review the Cost Optimization pillar for IoT that goes into details on how to architecture and observe costs. Please let us know if this answers your question!