Cloud Cost Engineering and Open Source FinOps
Notes from the team building C3X. Cost estimation for Terraform, the economics of cloud infrastructure, and how to ship FinOps tooling without a SaaS gate.
Training vs inference cost split: where the AI budget really goes
AI cost divides into training (building the model, often GPU-heavy and periodic) and inference (running it, continuous and scaling with usage). They have different profiles and different levers. Here is how to think about the split.
Understanding your Azure bill: reading the charges that matter
An Azure invoice mixes compute, storage, networking, and service charges across subscriptions and resource groups, which makes it hard to read. Knowing the structure, and where the big and surprising lines come from, is the first step to control. Here is how to read it.
Unexpected AWS charges explained: the usual bill surprises
Most surprise AWS charges come from a short list of usual suspects, data transfer, NAT gateways, idle resources, request fees, and forgotten services. Knowing them turns a mystifying bill into a fixable one. Here is the catalog of surprises.
us-east-1 vs us-west-2 cost: comparing two popular regions
us-east-1 and us-west-2 are two of AWS's cheapest and most feature-complete regions, with pricing that is close but not identical. Here is how they compare on cost, and what else to weigh beyond the sticker price.
Vector database cost compared: managed, self-hosted, and add-on
Vector databases for AI and search come as managed services, self-hosted engines, and add-ons to existing databases, each with a different cost model. Which is cheapest depends on scale, query volume, and operational appetite. Here is the comparison.
Vertex AI cost optimization guide: controlling GCP ML spend
Vertex AI cost spans training jobs, online prediction endpoints, notebooks, and pipelines, and the biggest drains are always-on endpoints and idle notebooks. Here is how to optimize each part of GCP's managed ML platform.
VMware to cloud cost: what leaving the hypervisor costs
Migrating VMware workloads to the cloud can mean a like-for-like lift onto managed VMware services or a re-architecture to native cloud. Each has a distinct cost profile, and recent VMware licensing changes have sharpened the math. Here is the breakdown.
VPC peering vs Transit Gateway cost: a deep dive
VPC peering is free to set up and charges only for data transfer; Transit Gateway adds hourly attachment and per-GB processing fees but scales connectivity cleanly. Which is cheaper depends on how many VPCs you connect. Here is the detailed comparison.
WAF cost explained: what web application firewall protection costs
AWS WAF bills per web ACL, per rule, and per million requests inspected, so cost scales with how many rules you run and how much traffic you protect. Here is how WAF pricing works and how to keep protection affordable.
What happens after AWS free tier ends: avoiding the cliff
The AWS free tier covers limited usage for twelve months (and some services always), and when it expires, resources that were free start billing at standard rates. Here is what changes, what to watch, and how to avoid a surprise bill.
When to buy reserved instances: timing the commitment right
Reserved instances save money on steady workloads but lock you into a commitment, so buying at the wrong time or for the wrong capacity wastes the discount. Here is how to decide when a workload is ready to reserve.
Why is my AWS bill so high: finding the real cost drivers
A high AWS bill almost always traces to a few dominant drivers, over-provisioned compute, data transfer, idle resources, and unmanaged growth, rather than a mystery. Here is how to find what is driving your bill and bring it down.
Why is us-east-1 the cheapest region: the default explained
us-east-1 (N. Virginia) is AWS's oldest, largest region, and it is consistently at or near the lowest prices and the first to get new services. Here is why it earned that status, and when the cheapest region is not the right choice.
Airflow cost on AWS: MWAA vs self-managed pricing
Running Apache Airflow on AWS costs money whether you use managed MWAA or self-host on EC2 or EKS. The bill is driven by environment size, worker scaling, and the compute your tasks actually launch. Here is how to size and control it.
AKS node pool cost optimization: paying less for Kubernetes
Azure Kubernetes Service is free for the control plane, but node pools (the VMs running your workloads) are where the cost lives. Right-sizing pools, using spot and autoscaling, and separating workload types cut the bill substantially. Here is how.
API Gateway REST vs HTTP API cost: which is cheaper
AWS API Gateway offers REST APIs and HTTP APIs at very different prices. HTTP APIs are substantially cheaper per million requests but drop some features. Here is the price gap, the feature tradeoffs, and how to choose.
AppSync vs API Gateway cost: GraphQL vs REST pricing
AWS AppSync (managed GraphQL) and API Gateway (REST and HTTP) are priced differently and suit different workloads. AppSync bills per query and real-time message; API Gateway bills per request. Here is how they compare and when each is cheaper.
Are AWS security groups free? Yes, and what actually costs money
AWS security groups are free, there is no charge for creating or using them. But the network resources they protect, and adjacent features like WAF and Network Firewall, do cost money. Here is what is free and what is not.
Are cloud data transfers free? The rules that decide
Some cloud data transfers are free (inbound, same-AZ private traffic) and some are expensive (egress to the internet, cross-region, cross-AZ). Knowing which is which is essential to avoiding surprise bills. Here is the map.
Athena vs Redshift Spectrum cost: querying S3 data compared
Both Athena and Redshift Spectrum query data in S3 and both charge per terabyte scanned, but their cost models and surrounding infrastructure differ. Here is how they compare and how to make either one cheap.
Aurora Serverless v2 cost explained: ACUs and when it pays off
Aurora Serverless v2 scales database capacity in fine-grained Aurora Capacity Units and bills per ACU-hour. It can save money on variable workloads but cost more on steady ones. Here is how the pricing works and when to use it.
AWS cost anomaly troubleshooting: finding what spiked your bill
When your AWS bill jumps unexpectedly, a systematic investigation, Cost Explorer, grouping by service and usage type, checking recent changes, finds the cause fast. Here is a step-by-step troubleshooting playbook.
AWS Local Zones cost: pricing for low-latency edge compute
AWS Local Zones place compute and storage closer to end users in metro areas, at prices higher than the parent region. Here is how Local Zones are priced, the data transfer implications, and when the latency is worth the premium.
AWS region pricing differences explained: why the same resource costs more elsewhere
The identical EC2 instance, S3 bucket, or RDS database costs different amounts depending on the AWS region. Understanding why, and which regions are cheapest, can meaningfully cut your bill. Here is the full explanation.