Top 6 Open Source Infrastructure as Code (IaC) Tools 2025

Infrastructure as Code (IaC) tools have revolutionized how organizations deploy and manage their cloud infrastructure, enabling teams to automate provisioning and ensure consistency across environments. In this guide, we explore the top IaC solutions for 2025 that help DevOps and platform engineering teams automate infrastructure at scale.

Criteria#

We evaluate IaC tools based on:

1. Adoption: Industry popularity and community support.
2. Capabilities: Core features and syntax approach.
3. Ecosystem: Cloud provider support and integrations.
4. Licensing Model: Open-source availability versus commercial offerings.

Terraform#

HashiCorp Terraform is the GOAT of IAC. It lets you define both cloud and on-prem resources in human-readable configuration files that you can version, reuse, and share. You can then use a consistent workflow to provision and manage all of your infrastructure throughout its lifecycle. Terraform can manage low-level components like compute, storage, and networking resources, as well as high-level components like DNS entries and SaaS features.

License: Commercial (Business Source License) - Terraform was open-source under the Mozilla Public License (MPL) until August 2023, when HashiCorp changed Terraform's license to the Business Source License (BSL). This licensing change led to the creation of OpenTofu, an open-source fork of Terraform maintained by the Linux Foundation.

Terraform uses configuration files (written in HashiCorp Configuration Language, HCL) to describe the desired infrastructure state. It then automatically provisions and manages resources based on that configuration.

Features

• Declarative Configuration: Defines infrastructure using HCL, focusing on what to build rather than how.
• Infrastructure as Code (IaC): Version-controlled, reusable, and Git-friendly infrastructure management.
• Multi-Cloud & Multi-Provider: Supports AWS, Azure, GCP, Kubernetes, VMware, and more.
• Execution Plan (terraform plan): Previews changes before applying, reducing risks.
• State Management: Tracks infrastructure changes via a state file (terraform.tfstate).
• Dependency Handling: Manages resource creation order automatically.
• Modular & Reusable: Supports Terraform modules for efficient, reusable configurations.
• Immutable Infrastructure: Ensures consistency by replacing resources when needed.
• Automation Integration: Works with Ansible, Chef, Puppet for additional provisioning.

Example

# Define the AWS provider
provider "aws" {
  region = "us-east-1"
}

# Create an EC2 instance
resource "aws_instance" "example" {
  ami           = "ami-0c55b159cbfafe1f0"  # Amazon Linux 2 AMI (change based on region)
  instance_type = "t2.micro"              # Small, free-tier eligible instance

  tags = {
    Name = "MyTerraformInstance"
  }
}

# Output the instance public IP
output "public_ip" {
  value = aws_instance.example.public_ip
}

Pulumi#

Pulumi enables developers to define, deploy, and manage cloud infrastructure using real programming languages like TypeScript, Python, Go, C#, and Java instead of domain-specific languages (DSL) like Terraform's HCL. This approach allows you to use the full power of the programming language to manage your infrastructure once restricted by the Terraform DSL.

License: Open Source (Apache 2.0) with Commercial Offerings - Pulumi's core functionality is open source, while their enterprise features are available through paid plans.

Pulumi supports multiple cloud providers, including AWS, Azure, Google Cloud, Kubernetes, and on-premises environments, offering a modern approach to IaC with native support for software engineering best practices.

Features

• Real programming languages: TypeScript, Python, Go, C#, and Java.
• Multi-Cloud & Multi-Provider: Supports AWS, Azure, Google Cloud, Kubernetes, and on-premises environments.
• Native support for software engineering best practices.
• Supports Terraform modules for efficient, reusable configurations.
• Immutable Infrastructure: Ensures consistency by replacing resources when needed.
• Automation Integration: Works with Ansible, Chef, Puppet for additional provisioning.

Example

import * as pulumi from '@pulumi/pulumi';
import * as aws from '@pulumi/aws';

// Create an AWS EC2 instance
const instance = new aws.ec2.Instance('myInstance', {
  ami: 'ami-0c55b159cbfafe1f0', // Amazon Linux 2 AMI (change based on region)
  instanceType: 't2.micro', // Small, free-tier eligible instance
  tags: { Name: 'MyPulumiInstance' },
});

// Export the instance public IP
export const publicIp = instance.publicIp;

Argo CD#

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes.

License: Open Source (Apache 2.0) - Argo CD is a Cloud Native Computing Foundation (CNCF) graduated project.

Argo CD follows the GitOps pattern of using Git repositories as the source of truth for defining the desired application state. It supports multiple configuration formats including Kustomize, Helm charts, Jsonnet, and plain YAML manifests. Akuity is a commercial offering that extends Argo CD with additional features.

Features

• Automated deployment and syncing of applications to target environments
• Multi-cluster management capabilities
• Automated configuration drift detection and visualization
• Web UI with real-time application activity monitoring
• Robust access controls with SSO integration and RBAC policies
• Advanced deployment strategies with PreSync, Sync, and PostSync hooks
• CLI for automation and CI integration

Crossplane#

Crossplane is an open source Kubernetes extension that transforms your Kubernetes cluster into a universal control plane.

License: Open Source (Apache 2.0) - Crossplane is a Cloud Native Computing Foundation (CNCF) incubating project.

Crossplane lets you manage anything, anywhere, all through standard Kubernetes APIs. Crossplane can even let you order a pizza directly from Kubernetes. If it has an API, Crossplane can connect to it.

With Crossplane, platform teams can create new abstractions and custom APIs with the full power of Kubernetes policies, namespaces, role based access controls and more. Crossplane brings all your non-Kubernetes resources under one roof.

Features

• Declarative configuration.
• Unify application and infrastructure configuration and deployment.
• One source of truth for infrastructure configuration and setup.
• Automate operational tasks with reconciling controllers.
• Built with high levels of extensibility.
• A strong separation of concerns.

Checkov#

Checkov is a static code analysis tool for scanning infrastructure as code (IaC) files for misconfigurations that may lead to security or compliance problems.

License: Open Source (Apache 2.0) - Checkov is developed by Bridgecrew, which was acquired by Palo Alto Networks. While Checkov itself is open source, it powers the commercial Prisma Cloud Application Security platform.

Checkov includes more than 750 predefined policies to check for common misconfiguration issues. Checkov also supports the creation and contribution of custom policies.

It scans cloud infrastructure provisioned using Terraform, Terraform plan, Cloudformation, AWS SAM, Kubernetes, Helm charts, Kustomize, Dockerfile, Serverless, Bicep, OpenAPI, ARM Templates, or OpenTofu and detects security and compliance misconfigurations using graph-based scanning.

It performs Software Composition Analysis (SCA) scanning which is a scan of open source packages and images for Common Vulnerabilities and Exposures (CVEs).

Checkov also powers Prisma Cloud Application Security, the developer-first platform that codifies and streamlines cloud security throughout the development lifecycle. Prisma Cloud identifies, fixes, and prevents misconfigurations in cloud resources and infrastructure-as-code files.

Features

• Over 1000 built-in policies for AWS, Azure and Google Cloud security and compliance
• Multi-platform scanning: Terraform, CloudFormation, Kubernetes, Dockerfile, Serverless, ARM, and more
• CI/CD integration: Scans Argo Workflows, Azure Pipelines, GitHub Actions, GitLab CI and other pipeline files
• Context-aware policies with graph-based scanning
• Supports multiple policy formats (Python and YAML)
• Detects credentials and secrets using pattern matching and entropy detection
• Evaluates provider settings and variables
• Supports suppression of false positives
• Multiple output formats: CLI, JSON, CSV, SARIF, and more

Example

checkov -f tf.json
Check: CKV_AWS_21: "Ensure all data stored in the S3 bucket have versioning enabled"
	FAILED for resource: aws_s3_bucket.customer
	File: /tf/tf1.json:224-268
	Guide: https://docs.prismacloud.io/en/enterprise-edition/policy-reference/aws-policies/s3-policies/s3-16-enable-versioning

		225 |               "values": {
		226 |                 "acceleration_status": "",
		227 |                 "acl": "private",
		228 |                 "arn": "arn:aws:s3:::mybucket",

DNSControl#

DNS configuration mistakes often draw the most blood. Look at Meta, Cloudflare. So you really need to consider IaC for DNS management.

DNSControl is a system for maintaining DNS zones - Infrastructure as code for DNS!

License: Open Source (MIT) - DNSControl was developed by Stack Exchange and is freely available under the MIT license.

It has two parts: a domain specific language (DSL) for describing DNS zones plus software that processes the DSL and pushes the resulting zones to DNS providers such as Route53, Cloudflare, and Gandi. It can send the same DNS records to multiple providers. It even generates the most beautiful BIND zone files ever. It runs anywhere Go runs (Linux, macOS, Windows). The provider model is extensible, so more providers can be added.

Features

• Less error-prone than editing a BIND zone file.
• More reproducible than clicking buttons on a web portal.
• Easily switch between DNS providers.
• Adopt CI/CD principles to DNS!
• Adopt PR-based updates.
• Variables save time.
• Macros.
• Control Cloudflare from a single source of truth.
• Keep similar domains in sync with transforms and other features.
• It is extendable.

Example

// define our registrar and providers
var REG_NAMECOM = NewRegistrar('name.com');
var r53 = NewDnsProvider('r53');

D(
  'example.com',
  REG_NAMECOM,
  DnsProvider(r53),
  A('@', '1.2.3.4'),
  CNAME('www', '@'),
  MX('@', 5, 'mail.myserver.com.'),
  A('test', '5.6.7.8'),
);