Checkov vs TFSec vs Terrascan: Top IaC Scanners Compared (2025)
An in-depth comparison of the top 3 open-source IaC security scanners: Checkov, TFSec, and Terrascan. We evaluate features, performance, usability, and CI/CD integration.
What You'll Learn
The Bottom Line
Checkov offers the broadest IaC and language support with a massive policy library. TFSec is the fastest and most developer-friendly for Terraform-centric workflows. Terrascan provides the most flexibility for custom policies using the power of Rego.
Quick Overview: Checkov, TFSec, Terrascan
Checkov
By Bridgecrew (Palo Alto Networks). A Python-based scanner known for its extensive support for numerous IaC frameworks (Terraform, CloudFormation, Kubernetes, ARM, etc.) and a library of over 1000 built-in policies.
- Best For: Multi-IaC environments, large organizations needing broad coverage out-of-the-box.
- Strengths: Widest framework support, graph-based analysis, huge policy library.
- Custom Policies: Python or YAML.
TFSec
By Aqua Security. A Go-based scanner originally laser-focused on Terraform, making it exceptionally fast and accurate. Now supports other languages but its core strength remains Terraform. Praised for its speed and developer-friendly output.
- Best For: Terraform-heavy teams, CI/CD pipelines where speed is critical.
- Strengths: Blazing speed, excellent Terraform parsing, simple custom policy format.
- Custom Policies: YAML or JSON.
Terrascan
By Tenable. A Go-based scanner that supports multiple IaC frameworks. Its key differentiator is using the Rego policy language (from OPA) for all its policies, offering powerful and flexible custom policy creation.
- Best For: Teams already using OPA/Rego, or those needing highly flexible and powerful custom policies.
- Strengths: Rego-based policies, flexible architecture, multi-IaC support.
- Custom Policies: Rego.
Feature-by-Feature Comparison
| Feature | Checkov | TFSec | Terrascan |
|---|---|---|---|
| Primary Maintainer | Palo Alto Networks | Aqua Security | Tenable |
| Language Written In | Python | Go | Go |
| Performance | Good (slower on large codebases) | Excellent (fastest) | Very Good (fast) |
| IaC Support | Terraform, CloudFormation, K8s, ARM, Serverless, Helm, Dockerfile & more | Terraform (primary), CloudFormation, K8s, JSON, YAML | Terraform, K8s, Helm, Dockerfile, CloudFormation |
| Policy Language | Internal (Python/YAML checks) | Internal (YAML/JSON checks) | Rego |
| Custom Policy Ease | Moderate (YAML), Complex (Python) | Easy (YAML) | Moderate to Complex (Requires Rego) |
| Installation | pip, brew, docker | brew, go install, docker | brew, curl, docker |
| Output Formats | CLI, JSON, JUnit, SARIF, CycloneDX | CLI, JSON, JUnit, SARIF, CSV, YAML | CLI, JSON, JUnit, SARIF, YAML |
| IDE Support | Excellent (VS Code via Prisma Cloud) | Good (Official VS Code extension) | Good (via OPA extension for Rego) |
| License | Apache 2.0 | MIT | Apache 2.0 |
Custom Policy Examples
Here's how to write a simple custom policy to ensure all AWS S3 buckets have versioning enabled in each tool.
Checkov (YAML Custom Policy)
# custom_policies/S3Versioning.yaml
metadata:
name: "Ensure S3 bucket has versioning enabled (Custom)"
id: "CKV_CUSTOM_AWS_1"
category: "BACKUP_AND_RECOVERY"
guideline: "S3 buckets should have versioning enabled to protect against accidental deletion."
definition:
and:
- resource_types:
- "aws_s3_bucket"
- cond_type: "attribute"
attribute: "versioning.0.enabled"
operator: "equals"
value: trueTFSec (YAML Custom Policy)
# custom_checks/s3_versioning.yml
- code: CUS001
description: "Custom check to ensure S3 buckets have versioning enabled"
message: S3 bucket does not have versioning enabled.
severity: ERROR
match:
type: resource
labels:
- aws_s3_bucket
as: s3
within:
type: block
labels: [ "versioning" ]
as: versioning
where:
attribute: enabled
is: false
remedy:
- "Enable versioning on the S3 bucket."Terrascan (Rego Custom Policy)
# custom_policies/S3Versioning.rego
package accurics
# Deny if an S3 bucket is found without versioning enabled
deny[res] {
some i
input.aws_s3_bucket[i].versioning[_].enabled != true
msg := "S3 bucket versioning is not enabled"
res := {
"Id": input.aws_s3_bucket[i].id,
"Message": msg,
"Severity": "HIGH"
}
}
# Also handle case where versioning block is missing entirely
deny[res] {
some i
not input.aws_s3_bucket[i].versioning
msg := "S3 bucket is missing the versioning block"
res := {
"Id": input.aws_s3_bucket[i].id,
"Message": msg,
"Severity": "HIGH"
}
}Strengths & Ideal Use Cases
Checkov is the Best Choice For:
- Diverse Environments: When your organization uses a mix of Terraform, Kubernetes, CloudFormation, and Docker, Checkov's broad support is a major advantage.
- Platform Teams: Ideal for central platform or security teams who need to enforce a wide range of policies across many different teams and technologies.
- Out-of-the-Box Coverage: If you want the largest possible set of pre-built checks without writing many custom policies, Checkov's library is unmatched.
TFSec is the Best Choice For:
- Terraform-Centric Teams: If Terraform is your primary IaC tool, TFSec's speed and deep understanding of HCL syntax are unparalleled.
- CI/CD Performance: When you need security scans to be lightning-fast to avoid slowing down pull request checks and deployments.
- Developer Experience: Its clear output, easy setup, and simple custom check format make it a favorite among developers.
Terrascan is the Best Choice For:
- Rego Expertise: If your team already uses OPA and is proficient in Rego, Terrascan is a natural fit, allowing you to reuse skills and even some policies.
- Complex Custom Policies: For requirements that go beyond simple attribute checks, Rego's logic-based language provides ultimate power and flexibility.
- Policy Unification: When you want to use the same policy language (Rego) for both your infrastructure (Terrascan) and your runtime environments (OPA).
When to Choose Which Tool
Decision Matrix
- My team uses many different IaC tools (Terraform, K8s, ARM...): Choose Checkov.
- Speed in our CI/CD pipeline is the top priority: Choose TFSec.
- My team's primary IaC tool is Terraform: Choose TFSec for its simplicity and speed.
- We need to write very complex, logic-heavy custom policies: Choose Terrascan.
- Our organization has already invested in OPA/Rego: Choose Terrascan.
- We want the largest number of built-in policies possible: Choose Checkov.
- My developers need a tool that is extremely easy to use and understand: Choose TFSec.
Final Recommendation
All three tools are excellent, open-source, and actively maintained by major security vendors. There is no single "best" tool, only the best tool for your specific needs.
Start with TFSec if you are primarily a Terraform shop. Its speed and simplicity provide the fastest path to value. If you find its custom policy engine too limiting or your IaC needs expand significantly, evaluate Checkov for its breadth or Terrascan for its policy power.