Jenkins
The original open-source automation server. Self-hosted, infinitely customisable, and still the backbone of many enterprise CI/CD pipelines.
Overview
Jenkins, originally created as Hudson in 2004 and forked to Jenkins in 2011, is the oldest and most widely used open-source automation server. It provides hundreds of plugins for building, testing, and deploying software. Jenkins is self-hosted, giving organisations complete control over their CI/CD infrastructure.
While newer tools like GitHub Actions and GitLab CI have gained popularity, Jenkins remains dominant in enterprises with complex, custom requirements that cloud-hosted platforms cannot satisfy.
What it's used for
Jenkins is essential when:
- Self-hosted CI/CD required: Data sovereignty, security, or compliance mandates on-premise infrastructure.
- Complex pipelines: Multi-stage pipelines with conditional logic, parallel execution, and custom integrations.
- Legacy system integration: Connect to mainframes, proprietary systems, or custom hardware.
- Plugin ecosystem needed: 1,800+ plugins for virtually any integration.
Pros & Cons
Pros
- Infinitely customisable with 1,800+ plugins
- Self-hosted — full control over infrastructure
- Free and open source
- Mature and battle-tested for 20+ years
- Massive community and extensive documentation
Cons
- High maintenance burden — requires dedicated admin time
- Plugin quality varies — some are outdated or unmaintained
- UI is dated compared to modern CI/CD platforms
- Security requires vigilance — Jenkins has had notable CVEs
- Scaling requires expertise (master-slave architecture, Kubernetes)
Platforms & Integrations
Jenkins runs on Windows, macOS, and Linux. It requires Java. It can be deployed on-premise, in the cloud, or on Kubernetes.
Pricing
| Tier | Cost | Includes |
|---|---|---|
| Open Source | Free | Full server, all plugins, community support |
| CloudBees | Custom | Enterprise Jenkins with support, security patches, and advanced features |
NZ Context
Jenkins is common in NZ government agencies and large enterprises with self-hosted infrastructure requirements. Inland Revenue and ACC use Jenkins for legacy system CI/CD. For NZ professionals, Jenkins experience remains valuable but is less in demand than GitHub Actions or GitLab CI among startups and modern SaaS companies.
Alternatives
- GitHub Actions — Cloud-native, zero-maintenance alternative for GitHub users.
- GitLab CI — Built-in CI/CD with better UX and self-hosted options.
- Azure DevOps — Microsoft's integrated CI/CD with strong enterprise features.