OpenSearch Service charge of almost 100 dollars, not to sure what is generating the charge.

The OpenSearch Service charge you're seeing is likely related to domain resources that may not be immediately visible in the dashboard. OpenSearch Service charges are based on the instance hours and storage provisioned for your domain, even if you don't see active queries or data ingestion happening.

Here are some things to check:

1. Verify that you don't have any OpenSearch domains running in other AWS regions. Make sure to check all regions in your account, as the console defaults to showing only the currently selected region.

2. Check for any domains that might be in a "Processing" or "Deleting" state, as these still incur charges until fully removed.

3. Review your AWS Cost Explorer or billing dashboard to see the specific OpenSearch Service line items. This will show you which region and resource is generating the charges.

4. Look for any CloudFormation stacks or other infrastructure-as-code deployments that might have created OpenSearch domains.

For a typical OpenSearch Service deployment with one node and 50 GB of storage running continuously, you can expect charges around $128 per month in US East (N. Virginia). If you're seeing charges but no visible domains, I recommend checking the AWS Cost Explorer for detailed resource-level billing information, and ensure you've checked all regions. If you need further assistance investigating these charges, you can reach out through the AWS Support Center at https://console.aws.amazon.com/support/ to add correspondence about your billing concerns.
Sources
Cost - Scene Intelligence with Rosbag on AWS

Hi,

To see exactly what's driving the charge, go to Cost Explorer and filter by:

• Service = Amazon OpenSearch Service
• Group by = Usage Type

That will break down the charge by usage type (e.g., storage, instance-hours, data transfer, snapshots), which usually points you straight to the cause even if no domain is currently visible in the console.

A few things worth checking specifically, since it's common to get charged with no domain visible:

• Check every region, not just the one you're currently viewing in the console
• If you ever purchased Reserved Instances for OpenSearch, those bill for the full term regardless of whether a domain is using them
• If you're part of an AWS Organization with consolidated billing, confirm the charge isn't coming from a different member account.

Hello.

What information is listed under the OpenSearch item on the invoice?
You can identify the regions where costs are being incurred and the reasons for them by checking your invoice or Cost Explorer.
https://repost.aws/knowledge-center/resources-unexpected-charges

It is convenient to have Amazon Q investigate whether any such unnecessary AWS resources remain, so please also check the following documentation.
https://docs.aws.amazon.com/amazonq/latest/qdeveloper-ug/chat-with-q.html