Blacksmith GitHub Actions Runners Docs: Tags, Setup and Pricing (November 2026)

Blacksmith is a hosted CI service that runs GitHub Actions jobs on its own runners. You install the blacksmith.sh GitHub App and change one line, runs-on: ubuntu-latest to a tag such as runs-on: blacksmith-4vcpu-ubuntu-2404. As of November 2026, the Blacksmith docs at docs.blacksmith.sh list Linux x64 and ARM runners from 2 to 32 vCPU, Windows Server 2025 runners, macOS runners at 6 and 12 vCPU, and 3,000 included x64 2 vCPU minutes a month per organization. If your jobs run on Ubuntu 24.04 x64 and price per minute is the deciding number, Sengi runs the same kind of job at $0.001 a minute (Sengi Basic, 2 vCPU), one-sixth of GitHub's $0.006.

This is a how-to reference: where each fact lives in the official Blacksmith documentation, the exact runner tags, the setup steps, how the included minutes are counted, and where Sengi fits for Linux x64 workloads.

Blacksmith runners at a glance (from docs.blacksmith.sh)

The table below summarizes the x64 Ubuntu 24.04 instance types listed on the Instance Types page of the Blacksmith docs (docs.blacksmith.sh/blacksmith-runners/overview, page dated October 29, 2026).

The same page lists matching sizes for Ubuntu 26.04 (blacksmith-*-ubuntu-2604), ARM (blacksmith-*-ubuntu-2404-arm and blacksmith-*-ubuntu-2604-arm, 6 GB to 96 GB of memory), Windows Server 2025 (blacksmith-*-windows-2025), and macOS on Apple Silicon M4 (blacksmith-6vcpu-macos-latest, blacksmith-12vcpu-macos-latest, plus pinned macos-15, macos-26 and macos-27 tags).

Blacksmith runners docs: where each topic lives on docs.blacksmith.sh

The Blacksmith docs home page (docs.blacksmith.sh) is organized into these sections:

• GitHub Actions Runners: Linux, macOS and Windows, x64 and ARM, 2 to 32 vCPU. The Instance Types page holds the tag tables, regions and the FAQ on included minutes.
• Caching: dependency caching, Docker layers, sticky disks and remote build cache.
• Git checkouts: a sticky disk with a snapshot of your repository, so checkouts fetch only new commits.
• Observability: logs, metrics, monitors, SSH and test analytics.
• Testbox: lets agents run commands inside a CI VM.
• CLI: logs, jobs, cache and usage from the command line.
• Administration: permissions, the GitHub App and network allowlisting.
• Pricing: the Instance Types page points to Blacksmith's separate pricing page for per-minute rates.

If you searched for "blacksmith runners docs" or "blacksmith.sh docs", the Instance Types page is the one that answers most runner questions: tags, sizes, regions, pre-installed packages and how minutes are counted.

Blacksmith runner tags for GitHub Actions

Blacksmith tags follow one pattern: blacksmith-<N>vcpu-<os>-<version>, with -arm appended for ARM. The Instance Types page states:

• Ubuntu 22.04 tags (blacksmith-*-ubuntu-2204 and blacksmith-*-ubuntu-2204-arm) are deprecated. Move x64 jobs to ubuntu-2404 or ubuntu-2604, and ARM jobs to ubuntu-2404-arm or ubuntu-2604-arm.
• Ubuntu x64 runners carry the same pre-installed dependencies as GitHub's official runner image; ARM runners follow GitHub's official ARM image.
• Windows runners are based on GitHub's Windows image with some exclusions, such as VS Build Tools 2022 in place of the full Visual Studio IDE. Docker Linux containers are not supported on Windows runners; Windows containers matching Windows Server 2025 run in process isolation mode.
• macOS macos-latest currently resolves to macOS 26. macOS 26 runners ship Xcode 26 (default) and Xcode 27; switch with xcode-select or DEVELOPER_DIR.
• Nested virtualization (KVM) is supported on x64 Linux runners, not on ARM.

How to set up Blacksmith runners in GitHub Actions

The Blacksmith docs describe the setup as a GitHub App install plus a one-line change:

1. Install the blacksmith.sh GitHub App on your GitHub organization.
2. Grant the app access to every repository that will use Blacksmith tags.
3. In each workflow, replace the runs-on value with a Blacksmith tag.

# .github/workflows/ci.yml jobs: build: runs-on: blacksmith-2vcpu-ubuntu-2404 steps: - uses: actions/checkout@v7 - run: make test 

Step 2 matters. The FAQ on the Instance Types page explains that Blacksmith uses GitHub's organization-level runner registration, so GitHub can hand a Blacksmith runner any queued job in the org that matches the tag. If repo foo has the app installed but bar and baz also use runs-on: blacksmith-*, the runners provisioned for foo can pick up jobs from bar and baz, and foo queues. The documented fix: install the app on every repository that uses a Blacksmith tag.

The docs also describe a right-sizing feature that finds jobs on the wrong size and opens a pull request to move them.

Blacksmith runners pricing and included minutes

The Instance Types page states that Blacksmith runners cost half of GitHub's per-minute rate and sends readers to the Blacksmith pricing page for the list. What the docs spell out in detail is how the 3,000 included minutes are counted. They are x64 2 vCPU minutes, per organization, per month, and every other runner consumes them at a multiplier:

The same page says that when the fleet has spare capacity, a runner can be bumped to the next tier at no additional cost, for example a blacksmith-4vcpu-ubuntu-2404 job running on 8 vCPU.

Caching, regions and concurrency

From the Instance Types page and the docs home page:

• Regions: us-east (Ashburn), us-west (Phoenix), eu-west (Amsterdam) and eu-central (Frankfurt). Moving an organization to another region goes through Blacksmith support.
• VMs: Linux and Windows jobs run in ephemeral Firecracker microVMs that the docs say boot in under 3 seconds.
• Concurrency: the FAQ states there is no limit on jobs or vCPUs running at once.
• Cache: official GitHub and popular third-party cache actions use Blacksmith's co-located cache transparently; Docker layer caching and sticky disks are documented under Caching.

Where Sengi fits

Sengi is a hosted GitHub Actions runner service for Linux x64 on Ubuntu 24.04. It has two classes, and the price is the headline.

• Sengi Basic is the lowest price: $0.001 a minute at 2 vCPU, $1 per 1,000 minutes, one-sixth of GitHub's $0.006.
• Sengi Premium is the faster class for CPU-bound builds that must finish sooner, at half GitHub's price.

Prices are Sengi's list prices and GitHub's hosted runner prices for the same sizes, November 2026. At 2 vCPU, 10,000 minutes a month is $10 on Sengi Basic, $30 on Sengi Premium and $60 on GitHub-hosted runners.

Every Sengi account starts with 3,000 included minutes a month, and you start without a card. Workflows, required checks and logs stay in GitHub, and every job runs in a fresh VM.

For Docker-heavy pipelines, Sengi publishes its own measurements. In Sengi's Docker build benchmark (measured October 27, 2026), the Atuin server image (Rust, cargo-chef) on sengi-premium-2-ubuntu-2404 built in 373 seconds cold and 104 seconds warm after a one-line source change, using docker/build-push-action@v7 with cache-from and cache-to type=gha,mode=max. At $0.003 a minute, that is $0.0186 for the cold build and $0.0052 for the warm one.

If your workflow runs on Ubuntu 24.04 x64, Sengi is the low-cost home for it. A side-by-side of runner labels, prices and setup is at https://sengi.run/compare/blacksmith.

Moving a job to Sengi

Moving a job is a one-line runs-on change, the same shape as the Blacksmith setup:

jobs: test: runs-on: sengi-basic-2-ubuntu-2404 steps: - uses: actions/checkout@v7 - run: make test build: runs-on: sengi-premium-8-ubuntu-2404 steps: - uses: actions/checkout@v7 - run: make build 

A practical pattern: put tests, linters and short jobs on Sengi Basic for the lowest bill, and put CPU-bound compiles on Sengi Premium. Required checks keep their job names, so branch protection keeps working. A step-by-step walkthrough of switching runners is at https://sengi.run/blog/switch-github-actions-runners.

Sengi also serves teams whose AI coding agents (Claude Code, Codex and others) run CI in GitHub Actions, where every agent push adds billed minutes; at $0.001 a minute those runs stay cheap.

FAQ

What is Blacksmith in GitHub Actions?

Blacksmith is a hosted CI service that runs GitHub Actions jobs on its own runners. You install the blacksmith.sh GitHub App and set runs-on to a Blacksmith tag such as blacksmith-2vcpu-ubuntu-2404, as described on docs.blacksmith.sh.

Where are the Blacksmith runners docs?

The docs live at docs.blacksmith.sh. The Instance Types page (docs.blacksmith.sh/blacksmith-runners/overview) covers runner tags, sizes, regions, pre-installed packages and how included minutes are counted.

How many included minutes does Blacksmith give?

The Instance Types FAQ lists 3,000 x64 2 vCPU minutes per month per organization. Larger, ARM, Windows and macOS runners draw them down at multipliers, for example 20x for macOS 6 vCPU.

Why are my Blacksmith jobs queuing in some repositories?

The Blacksmith docs trace this to repositories that use runs-on: blacksmith-* without the blacksmith.sh GitHub App installed. Install the app on every repository that uses a Blacksmith tag.

What does Sengi cost per minute?

Sengi Basic costs $0.001, $0.002 and $0.004 a minute at 2, 4 and 8 vCPU, one-sixth of GitHub's $0.006 at 2 vCPU. Sengi Premium costs $0.003, $0.006 and $0.012 a minute, half GitHub's price.

Which operating systems does Sengi support?

Sengi runs Ubuntu 24.04 on Linux x64, at 2, 4 and 8 vCPU. Labels follow the pattern sengi-basic-2-ubuntu-2404 and sengi-premium-8-ubuntu-2404.

How do I move a GitHub Actions job to Sengi?

Change one line: runs-on: sengi-basic-2-ubuntu-2404. Workflows, required checks and logs stay in GitHub, every job runs in a fresh VM, and you start with 3,000 included minutes a month without a card.