“### 1. GitHub Actions — easiest if you're already on GitHub”
“Good default for GitHub-centric teams”
“Best cost optimization: Use self-hosted ephemeral runners with autoscaling for bursty workloads, and GitHub-hosted runners for workloads where managing infrastructure isn't worthwhile.”
“An important distinction: GitHub's concurrency setting is not a way to buy more parallelism.”
“### 2. GitLab CI/CD — strong for shared infrastructure”
“Good for centralized runner pools”
“GitLab shared runners use fair scheduling to avoid one project monopolizing capacity.”
“### 3. CircleCI — high concurrency without necessarily paying for concurrency itself”
“Good for high-volume cloud CI”
“One particularly interesting aspect is its billing model: you pay for compute consumption rather than simply having access to more concurrency.”
“### 4. Buildkite — excellent when you want control over execution infrastructure”
“Strong choice for large engineering organizations”
“An interesting feature is its approach to burst capacity: Buildkite says self-hosted agent charges reflect sustained monthly usage rather than isolated peaks, so temporary bursts don't automatically result in unexpected overage charges.”
“### 5. Jenkins — maximum infrastructure flexibility”
“Jenkins is still worth considering if you want to avoid per-job SaaS pricing.”
“There is no fixed commercial concurrency ceiling imposed by Jenkins itself.”
“The trade-off is operational overhead: you own upgrades, plugin maintenance, availability, scaling and security.”
“### 6. Tekton — Kubernetes-native CI/CD”
“Tekton is particularly attractive if your organization already operates Kubernetes at scale.”
“There is no per-concurrent-job SaaS license fee for the open-source project itself.”
“However, Kubernetes infrastructure, storage, networking and operational complexity still cost money.”