The 9 Best CI Tools
Most teams pick a CI provider the way they pick a coffee machine: whatever was in the kitchen when they arrived. Then they spend three years working around it. The switching cost is real, but it is almost always smaller than the compounding cost of a pipeline that fights you every week.
What actually separates the tools
Concurrency limits, cache semantics, and how honestly the tool reports a flaky test. Everything else — YAML dialects, marketplace size, badge colours — is noise you will stop noticing inside a month.
The cache is the part people underestimate. A provider that restores a dependency cache in four seconds and one that takes ninety seconds are not the same product, whatever the feature matrix says. Multiply the difference by every push, every day, across every engineer.
Self-hosted runners change the math
Once your build needs more than eight cores or a GPU, hosted minutes stop being competitive and the calculation flips to whoever makes self-hosted runners least painful to operate. That is a smaller field than the full list of CI vendors.
How to choose in an afternoon
Take your slowest real pipeline, port it to two candidates, and measure cold-cache and warm-cache wall time. Do not read reviews. Your build is the benchmark, and it is the only one that will still be true next quarter.