Kubernetes makes it easy to scale. But it also makes it easy to overspend.
Here’s the good news: with the right FinOps tools, many companies save 20–50% on their Kubernetes bills. Some even cut costs in half, without slowing developers down, by adding visibility and guardrails into their workflow.
In this post, you’ll learn about 3 open-source tools that can help you do the same.
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The €30k Surprise Bill
A SaaS company built fast on AWS. They launched features, opened new services, and scaled traffic. After six months, the finance team opened the bill.
It had jumped from €5k/month to €30k/month.
Why?
- Development servers left on all night.
- Pods over-provisioned with CPU and memory.
- Old test clusters never removed.
- No one knew which team owned which resource.
This isn’t rare. Ouribank, a Brazilian fintech, saw its own cloud infrastructure costs quadruple for the very same reasons: missing visibility, no tagging, and unmanaged growth. After introducing FinOps practices, automating shutdowns, tagging ~92% of resources, and rightsizing workloads, they cut costs by nearly 60%. You can read the full story here: FinOps on AWS helps Ouribank cut costs by 60%.
The lesson is clear: this isn’t bad engineering. It’s missing visibility and accountability. And that’s exactly what FinOps brings.
How FinOps Fixes the Problem
What is FinOps?
FinOps is the practice of bringing financial accountability to the cloud. Instead of just looking at cost savings, it helps teams make smart trade-offs between speed, cost, and business value.
1. Visibility
FinOps makes cloud costs transparent. Teams see who spends, on what, and why.
2. Guardrails
With simple rules and automation, you can reduce spend quickly. Turn off dev servers at night. Resize big VMs. Remove unused storage.
3. Culture
Engineers see cloud cost as one more metric, like latency or uptime. Finance and product managers understand cost in real time. Everyone speaks the same language.
The 3 FinOps Tools That Change Everything
1. Kubecost — Visibility Inside the Cluster
Kubecost links your cloud bill directly to your Kubernetes workloads. Instead of one big AWS invoice, you see:
- Cost per namespace,
- Which deployments are the most expensive,
- Where resources are being wasted.
Suddenly, you can point to the “search” service and say, “This eats 40% of our cluster budget.” Now the problem is visible and actionable.
How to use it: install Kubecost with Helm, connect it to billing data, and review dashboards weekly. Start by fixing your top 3 costly workloads.
Example: A retail startup discovered a dev namespace costing €8k/month. After cleaning up unused pods and right-sizing workloads, they cut that in half — freeing budget for new product features.
👉 Learn more at kubecost.com
2. OpenCost — The Open Standard for Cost Data
OpenCost is the open standard for Kubernetes costs. It powers Kubecost but can also run standalone. It exposes accurate cost metrics per pod, node, or service through an API, so you can plug it into Prometheus, Grafana, or any BI tool.
Cost data becomes just another metric in your monitoring stack, like CPU or latency. And because it’s open, you avoid vendor lock-in.
How to use it: deploy OpenCost, scrape the /allocation/ API with Prometheus, and build dashboards in Grafana.
Example: A SaaS company built Grafana dashboards showing latency, CPU, and cost per service side by side. Product managers could now weigh performance vs. cost in roadmap decisions.
👉 Learn more at opencost.io
3. Infracost — Cost Awareness Before You Deploy
Kubecost and OpenCost help you see what’s happening inside your Kubernetes clusters. Infracost, on the other hand, focuses on what happens before infrastructure is deployed.
It is especially valuable for teams using Infrastructure as Code (IaC). Infracost integrates with Terraform pipelines and adds cost estimates directly into pull requests: “This change adds €1,200/month.”
This means engineers see the financial impact of infra changes while coding, not weeks later when the bill arrives. Cost becomes part of the development workflow, not an afterthought.
How to use it: install the Infracost CLI, connect it to your cloud billing, and integrate it into your Terraform CI/CD pipeline (GitHub Actions, GitLab CI, Jenkins, etc.). Every Terraform PR will now include a cost estimate.
Example: A fintech company planned a new RDS cluster in Terraform. Infracost flagged the PR: “+€3,000/month.” They redesigned with a smaller instance plus caching, achieving the same performance at one-third of the cost.
👉 Learn more at infracost.io
Why These Tools Matter
Together, these tools form a FinOps starter kit for Kubernetes:
- Kubecost makes spending visible.
- OpenCost provides open, flexible cost data.
- Infracost shifts cost awareness left, into Terraform PRs.
You don’t need all three at once. Start with the tool that solves your biggest pain:
- Blind to cluster costs? Start with Kubecost or OpenCost.
- Tired of surprise bills in Terraform? Start with Infracost.
The win is not the tool itself, it’s how it changes behavior. Cloud costs stop being abstract and become part of everyday engineering.
The Bottom Line
Kubernetes is powerful, but without FinOps it can quietly drain budgets. By making costs visible, building guardrails, and teaching engineers to care about cost, companies regularly save 20–50% of their cloud bill.
If you run Kubernetes, try one of these tools this week. Even a single cleanup or rightsizing step can pay for itself — fast.
Want more hands‑on tips about Kubernetes, Cloud, and DevOps?
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