My defaultAWSCost analysis

Cost Explorer (with Claude Code)

Where every cost investigation starts. I let Claude Code read it and find the culprit.

Group by service, then usage type, then operation. An agent with read-only access does this in minutes.

Use it when

Monthly bill reviews and any surprise on the invoice.

Gotchas, with fixes

Gotcha: Operation names can mislead: CloudWatch log ingestion shows as 'PutLogEvents' but is billed per GB.

Fix: Group by usage type as well as operation.

Where it fits

An AWS foundation for a client: Pick 05.
Monthly review, with an agent doing the digging.

Last reviewed 18 October 2026 by Nicolas Dao

Also in Accounts, identity and cost

Default Amazon Cognito: Authentication
Default AWS Backup: Backups
Default AWS Organizations + IAM Identity Center: Accounts and access
Default Better Auth: Authentication library, users in your Postgres
Default Savings Plans and Reserved Instances: Cost

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