Sengi vs Blacksmith: GitHub Actions runners compared

Sengi or Blacksmith: which GitHub Actions runner costs less?

Sengi. At 2 vCPU it is $0.003 a minute against Blacksmith's $0.004, 25% less, and 25% less at 4 and 8 vCPU too. The same Rust, TypeScript and Docker builds cost less in total: $0.069 on Sengi against $0.073 on Blacksmith at 4 vCPU, on RunsOn's open benchmark harness. Docker layer caching is included instead of sold per GB, personal repositories work as well as organizations, and the switch is one runs-on line your coding agent can open as a pull request. Both include an Actions cache.

Last checked October 9, 2026, against Blacksmith's published pricing and RunsOn's open benchmark harness. Prices in USD.

How do Sengi and Blacksmith compare?

Both keep your CI in GitHub Actions and replace the machine behind runs-on. Here is where they differ.

No subscription and no monthly minimum.

What does Sengi vs Blacksmith cost?

On the matched 2 vCPU, 8 GB runner: $0.003 a minute on Sengi, $0.004 on Blacksmith. Add Docker layer caching and the gap widens, because Sengi includes it.

The same builds cost less in total, too. On RunsOn's open benchmark harness, run on Sengi October 9, 2026, a Rust build, a TypeScript typecheck and a production Docker image at 4 vCPU cost $0.069 together on Sengi, against $0.073 on Blacksmith in RunsOn's published results.

Speed cuts the bill too, because a job that finishes sooner bills fewer minutes. Against GitHub’s runner on RunsOn’s open benchmark harness at 4 vCPU, Sengi builds a production Docker image 1.9× faster at 74% less per build, and runs the Rust, TypeScript and Docker builds together 1.8× faster at 72% less. Warm Docker builds run 1.9× faster again with layer caching. Put in your own minutes with the GitHub Actions cost calculator, or see Sengi runner pricing and GitHub's own rates.

Why choose Sengi over Blacksmith?

• 25% lower rate at every size: $0.003 a minute for 2 vCPU against Blacksmith's $0.004. Then $0.006 for 4 vCPU against $0.008, and $0.012 for 8 vCPU against $0.016.
• A smaller build bill: $0.069 for the Rust, TypeScript and Docker builds at 4 vCPU on RunsOn's open benchmark harness, against $0.073 on Blacksmith.
• Measured speed: up to 2.75× the multi-core and 1.6× the single-core CPU of GitHub’s 2 vCPU runner, on the same CPU model every job.
• Pre-booted runners: your 2 vCPU job lands on a VM that’s already running, ready in 2 seconds.
• Docker layer caching included: layers persist between runs through type=gha at no charge. Blacksmith sells it at $0.50 per GB per month.
• Personal repositories: Sengi runs them alongside organization repositories. Blacksmith requires an organization.
• Built for coding agents: paste one prompt and your agent finds every eligible job and opens the pull request.

How do I switch from Blacksmith to Sengi?

Change one line. Replace the Blacksmith label in runs-on with sengi-standard-2-ubuntu-2404, or the 4 or 8 vCPU label, and merge. Or connect GitHub and hand your coding agent the Sengi prompt; it opens the pull request for you. Switching back is one revert.

Blacksmith figures come from its published pricing, instance-type, quickstart and caching pages, checked September 30, 2026.

Frequently asked questions

Is Sengi a Blacksmith alternative?

Yes. Sengi runs GitHub Actions jobs on bare-metal 5 GHz desktop CPUs, each on a fresh VM, at $0.003 a minute for 2 vCPU against Blacksmith's $0.004. It includes the Actions cache and Docker layer caching at no added charge, and it runs personal repositories as well as organizations.

How does Blacksmith pricing compare with Sengi?

For the matched 2 vCPU, 8 GB Ubuntu x64 runner, Sengi charges $0.003 per minute and Blacksmith lists $0.004, so Sengi is 25% cheaper, and the gap is the same 25% at 4 and 8 vCPU. On RunsOn's open benchmark harness, the same Rust, TypeScript and Docker builds at 4 vCPU cost $0.069 in total on Sengi against $0.073 on Blacksmith. Sengi includes Docker layer caching; Blacksmith lists it at $0.50 per GB per month.

Does moving to Sengi or Blacksmith replace GitHub Actions?

No. Both run your GitHub Actions jobs; your workflows stay GitHub Actions workflows and only the runs-on label changes. With Sengi you change it by hand, or your coding agent opens the pull request from the Sengi prompt.

Which service has better caching for GitHub Actions?

Sengi includes both caches. actions/cache, the setup actions' caches and Docker layer caching through type=gha are all served from Sengi's own cache with no workflow changes and no added charge. Blacksmith includes an Actions cache and sells Docker layer caching and sticky disks at $0.50 per GB per month each.

Can I use Sengi on a personal repository?

Yes. Sengi runs personal and organization repositories alike. Blacksmith requires a GitHub organization.

Is Blacksmith the same as self-hosting GitHub Actions runners?

No. Blacksmith and Sengi are managed runner services: the provider runs the machines, images, scaling, isolation and recovery. With self-hosting, all of that is your team's job.