Compare GitHub Actions runners: StarSling vs GitHub-hosted, Depot, Blacksmith, and WarpBuild
StarSling is AI-native CI for GitHub Actions: a drop-in runner replacement with AI agents that open optimization PRs. These pages put it side by side with the runner and build-acceleration tools teams evaluate.
The alternatives run jobs faster. Only StarSling also opens AI optimization PRs that improve the pipeline over time. Where the alternatives differ from each other is the runner families they publish and what they attach to the Docker build.
For new accounts, AI-powered optimization PRs are only available to customers on paid plans and are not enabled by default.
| Tool | Faster runners | AI optimization PRs | Runner families | Docker builds | Primary focus |
|---|---|---|---|---|---|
| StarSling | Yes | Yes | Linux only: Ubuntu 24.04 | No separate build service: Docker builds run in your workflow on faster hardware, and the agents open PRs that fix the build and cache steps | Self-driving CI: fast runners plus agents that open optimization PRs to enforce best practices |
| GitHub-hosted | No | No | Linux, macOS, and Windows (hosted-runner reference, checked 2026-07-14) | Runs in your workflow on GitHub's shared hardware; layer caching only through BuildKit's GitHub Actions cache backend (type=gha), with no remote builder (checked 2026-07-14) | Default GitHub Actions runner infrastructure |
| Depot | Yes | No | Linux, macOS, and Windows (runner types, checked 2026-07-14) | Remote BuildKit builders that run in the same private network as the runner, each with a persistent NVMe layer cache (50 GB, expandable). Depot Cache is a distinct product, a remote cache for GitHub Actions, Bazel, Go, Gradle, Turborepo and more (checked 2026-07-14) | Container builds, Depot Cache, GitHub Actions runners, and Depot CI (products, checked 2026-07-14) |
| Blacksmith | Yes | No | Linux x64 and ARM and macOS, with Windows Server 2025 in public beta (instance types, checked 2026-07-14) | Docker layer caches kept on per-Dockerfile sticky disks that persist between runs, billed per GB-month (checked 2026-07-14) | Fast drop-in runners plus caching and build infrastructure; its docs list no agent that opens optimization PRs (checked 2026-07-14) |
| WarpBuild | Yes | No | Linux x64 and ARM64, macOS, and Windows (cloud runners, checked 2026-07-14) | Remote "Docker builders" with Buildx integration, each builder profile keeping a persistent layer cache, plus a WarpBuilds/cache action documented as a drop-in for actions/cache@v4 (checked 2026-07-14) | Fast drop-in runners plus a container-build service; its docs list no agent that opens optimization PRs (checked 2026-07-14) |
Real results from StarSling customer workflows
These are StarSling's published customer measurements, not benchmark claims about Depot, Blacksmith, WarpBuild, or GitHub-hosted runners. Each result links to the case study that explains the measurement window, source method, and caveats.
lower compute cost per run on Partcl's heaviest CI jobs
faster test suites at Mastra
faster E2E tests at Better Auth
- Better Auth: after migration and three agent PRs, E2E went from 2m 22s to 1m 04s and CI went from 1m 40s to 1m 02s.
- Mastra: agents opened fourteen PRs across sleeps, polling, Docker healthchecks, sharding, race fixes, and runner migration; Combined store Tests measured 29m 56s to 5m 06s in the post-migration window.
- Partcl: on a synthesis-bound CI workload, the agents shipped eight optimization PRs, cut heaviest-job compute cost 13x per run, and reduced p95 queue time from 9.5 minutes to 35 seconds.
StarSling vs GitHub Actions
GitHub Actions is the default CI for GitHub repositories, and GitHub-hosted runners (ubuntu-latest, ubuntu-24.04) are its standard runner infrastructure.
StarSling vs Depot
Depot builds a broad CI platform: accelerated container builds, a distributed remote cache, GitHub Actions runners, and its own CI engine.
StarSling vs Blacksmith
Blacksmith provides fast, drop-in GitHub Actions runners on better hardware, with runner families beyond Linux and build-infrastructure features such as caching.
StarSling vs WarpBuild
WarpBuild is a fast, drop-in GitHub Actions runner with a container-build service attached.
Which GitHub Actions runner is right for me?
If you want faster runs and a pipeline that keeps improving itself, StarSling combines fast drop-in runners with AI agents that open optimization PRs. If you only need raw runner speed, any fast-runner provider works; if your main bottleneck is Docker image builds, a build-acceleration tool like Depot fits.
Do these runners work with my existing GitHub Actions workflows?
Yes. StarSling and the other drop-in runners run your existing workflows; you switch by changing the runs-on label. StarSling's label is starsling-ubuntu-24.04.
How do Blacksmith and WarpBuild compare?
Both are drop-in GitHub Actions runners, and the difference is what each attaches to the runner. Blacksmith publishes Linux x64/ARM and macOS runner families up to 32 vCPU on Linux, with Windows Server 2025 in public beta, and keeps Docker layer caches on per-Dockerfile sticky disks billed per GB-month (instance types, Docker build caching). WarpBuild leans on a container-build service: remote "Docker builders" with Buildx integration with a persistent layer cache per builder profile and native amd64/arm64 builds, plus a WarpBuilds/cache action documented as a drop-in replacement for actions/cache@v4 (Docker builders, caching). Both checked 2026-07-14. Neither opens optimization PRs against your workflow, which is the axis StarSling is on.
What makes StarSling different from other fast runners?
StarSling adds AI agents that analyze your workflows, logs, and telemetry and open pull requests that optimize caching, dependency installs, parallelization, and test sharding, applying the GitHub Actions CI best practices an expert would by hand. Other runners make jobs faster; StarSling also improves the pipeline over time.
Last updated 2026-07-16