Free infrastructure as code scanners are good at catching well-known misconfigurations, such as open storage buckets or unencrypted disks, before they reach production. They are weaker at context: they rarely know which resources are exposed, who owns a finding, or how rules map to your policies. Start free, then add what you miss.
What do free IaC scanners usually include?
Most free options fall into three groups. Open source policy scanners read Terraform, CloudFormation, Kubernetes manifests or similar files and match them against a rule library. Editor plugins and linters give the same kind of feedback inside the IDE. Cloud platforms also offer built-in configuration checks that evaluate resources after they exist.
The rule libraries often draw on public hardening guidance. The CIS Benchmarks, for example, are consensus configuration recommendations that cover the major cloud platforms and managed Kubernetes services, and many rule sets reference them. A scanner that cites a benchmark control gives you something to point at when a developer asks why a rule exists.
Where do they stop?
Free tools tend to share the same limits. None of these is a flaw in the idea. They are the edges to plan around.
- Source only. A scanner that reads files cannot see what an engineer changed by hand in a console. Drift between code and reality is a separate problem.
- Noise without context. A rule that fires on every dev bucket looks the same as one that fires on a production database. Severity from a rule file is not the same as risk.
- Weak ownership. A finding without a team attached sits in a report. Free output is usually a list, not a workflow.
- Custom policy is work. Writing and testing your own rules takes engineering time, and rules need upkeep when providers change.
- Limited evidence. Auditors ask for proof that checks ran on every change. Raw tool logs rarely map neatly to a control.
- Modules and third-party code. Shared modules pulled from registries carry their own risk, and not every free tool resolves them well.
What buyer criteria matter when free is not enough?
When you compare paid options, ask these questions, and ask them of any vendor, including us.
- Which languages and formats does it parse, and which versions?
- Can it check a plan or a rendered result, not just source files?
- Can you write custom rules, and how are they tested?
- Does it link a finding to the resource owner and the code line?
- Can it suppress a finding with an expiry date and a reason?
- Does it produce reports in a form your auditor accepts?
- Where does the scan run, and does your code leave your network?
How should you roll out a free scanner?
Begin in report mode on a single repository. Look at the first batch of findings with the owning team and sort them into three piles: fix now, accept with a reason, and rule is wrong for us. Only then turn a few high-confidence rules into blocking checks on pull requests. Blocking everything on day one trains people to bypass the tool.
Keep the rule set small. A dozen rules everyone trusts do more good than three hundred that people mute. Review the list once a quarter.
Safeguard's CLI and local runner can scan on your machine so source stays local, and Safeguard policy gates can enforce at checkpoints. A free scanner may be all a small team needs. Compare on the criteria above and decide on evidence.
What to do
- Pick one free scanner and run it in report mode on one repository.
- Triage the first findings with the owner and record decisions.
- Promote a short list of high-confidence rules to blocking on pull requests.
- Add a drift check, since source scanning cannot see console changes.
- Write down the gaps you hit, and use that list as your buying criteria.
Quick check
Are free IaC scanners enough for compliance?
They help, but audits ask for evidence that checks ran on every change and that exceptions were approved. Plan how you will keep that evidence.
Should scan results block every pull request?
Not at the start. Begin in report mode, then block on a small set of rules your team trusts.
Sources
Last reviewed: 18 October 2026.
