Blacksmith

Faster, cheaper runners for GitHub Actions: change the runs-on label, keep your workflows.

ProprietaryFreemium#ci#github-actions#runners#docker#macos

What is Blacksmith?

Blacksmith runs GitHub Actions jobs on its own hardware. You install its GitHub app on an organisation and change a job's runs-on label, for example to blacksmith-4vcpu-ubuntu-2404. GitHub still schedules the workflow; Blacksmith starts each job in a Firecracker microVM on bare-metal machines with gaming CPUs. Runners come in Linux x64 and ARM (2 to 32 vCPU), Windows (public beta) and macOS on Apple M4, next to a co-located Actions cache and a persistent Docker layer cache used through its open-source actions.

Blacksmith Software Inc., founded in 2024, sells the service per runner minute. The service is proprietary; the actions are open source (setup-docker-builder is Unlicense). On 21 October 2026 it announced a Series C led by Sequoia at a $1B valuation, bringing its total raised to $125M.

It says it now runs more than 90 million jobs a week, up from 5 million in January 2026, in four regions (Ashburn, Phoenix, Amsterdam, Frankfurt). On 6 November 2026 it disclosed unauthorised access to its job-log store. Its closest competitor is Namespace; the other options are GitHub's own larger runners or self-hosting.

Our review

4.0

The least effort way to make slow or expensive GitHub Actions jobs faster: you change one label and the workflows stay as they are. You are still on GitHub Actions, though, with its control plane and its outages, and you add a vendor that stores your job logs. Its 6 November 2026 security notice about unauthorised access to those logs is reason to check what your jobs print.

Pros

+ Migration is a runs-on label change, on the same images as GitHub's runners
+ Per-minute Linux rates are a third below GitHub's ($0.004 vs $0.006 for 2 vCPU), with 3,000 free minutes a month and no concurrency cap
+ Docker layer caching on persistent disks, without cache-from/cache-to plumbing

Cons

− Works only with GitHub Actions in GitHub organisations; it inherits GitHub's scheduling outages
− Unauthorised access to its CI job-log store on 5 November 2026 (about 2.6% of accounts); the full report is still pending
− macOS costs more per minute than GitHub's standard macOS runner; the saving depends on jobs actually running faster

Reviewed by SeekDeploy Editorial · updated 2026-11-15. Reviews are independent — we don’t accept payment for coverage or ratings.

Should you use Blacksmith?

A good fit if you're…

Teams already on GitHub Actions whose jobs are slow or whose Actions bill is growing, and who want no workflow rewrite
Docker-heavy pipelines that rebuild images on every push and want layer caching without registry cache plumbing
Test suites sharded wide (16+ jobs per push) that queue under GitHub's concurrency limits

Probably not for you if you're…

Personal GitHub accounts and repositories outside an organisation: Blacksmith does not support them
Anyone not on GitHub Actions (GitLab CI, CircleCI, Buildkite); it is a runner provider, not a CI system
Teams that cannot let a third party store CI job logs or run their code

Pick something else if…

you also want Bazel remote execution, remote Docker builders outside Actions, or cloud dev environments → Namespace
your private-repo minutes fit the plan allowance and jobs are not slow enough to matter → GitHub Actions
code and compute must stay on your own machines → Buildkite

Gotchas to know before you commit

Job logs are stored by Blacksmith. On 5 November 2026 an unauthorised party accessed the job-log store; Blacksmith says about 2.6% of accounts were affected and contacted, CI execution was not, and a full report will follow (status notice, 6 November 2026). Make sure jobs do not print secrets.
GitHub still schedules every job, so GitHub Actions outages stop Blacksmith jobs too. If GitHub brings back its postponed $0.002 per minute platform fee for self-hosted runners, Blacksmith's own blog (16 December 2025) says it applies to third-party runners like Blacksmith.
Install the GitHub app on every repository that uses blacksmith-* labels. Otherwise runners provisioned for one repository can pick up another repository's jobs and the first one's jobs queue (runner FAQ).
Caches are disposable. Docker layers unused for 8 days are garbage-collected, and on 7 November 2026 a us-west sticky-disk outage (2 h 37 min) ended with some sticky disks purged.
Windows runners are a public beta without full Visual Studio, and they cannot run Linux containers. Ubuntu 22.04 runner labels are deprecated.

Blacksmith pricing

Checked Nov 15, 2026 against the official pricing page

Pay per runner minute, scaled by vCPU: Linux x64 is $0.004 per minute for 2 vCPU and doubles with each size, ARM is 37.5% cheaper, Windows double, macOS $0.08 for 6 vCPU. Every organisation gets 3,000 free 2-vCPU minutes ($12 of usage) a month. Costs climb with large runners and macOS, and with the per-GB cache add-ons.

Pay as you go

$0 / month + usage

GitHub organisations of any size

3,000 free 2-vCPU Linux minutes per organisation / month
Linux x64: $0.004 (2 vCPU), $0.008 (4 vCPU), $0.016 (8 vCPU) per minute
ARM $0.0025, Windows $0.008 per minute at 2 vCPU
macOS M4: $0.08 (6 vCPU), $0.16 (12 vCPU) per minute
No concurrency limit

Limit: Docker layer cache and sticky disks: $0.50 / GB / month
Limit: Static IPs: $100 / IP / month
Limit: GitHub organisations only, not personal accounts

Enterprise

Contact sales

99.9% SLA
24/7 priority support and a dedicated Slack channel
Onboarding and CI optimisation help

Limit: Price not published

What it costs in practice

Team running 20,000 Linux minutes / month on 4 vCPU	~$148 / month 20,000 × $0.008 = $160, minus the free 3,000 2-vCPU minutes (3,000 × $0.004 = $12) = $148. Add $0.50 per GB-month if you use the Docker layer cache (50 GB = $25).
Small org: 1,500 Linux minutes / month on 2 vCPU	$0 1,500 minutes fits inside the 3,000 free 2-vCPU minutes.
iOS app: 2,000 macOS minutes / month on 6 vCPU M4	~$148 / month 2,000 × $0.08 = $160, minus $12 free = $148. GitHub's standard macOS runner is $0.062 per minute ($124 for the same minutes), so Blacksmith only saves money if jobs finish faster, as the vendor claims.

Estimates in USD from list prices. Your bill depends on usage, region, and discounts.

Health & activity

Updated Nov 15, 2026 · last 90 days

Closed sourceThe product itself isn't public. The figures below are for its public companion repo, so treat them as a partial view.

GitHub stars

13 forks

Commits

5 committers

Merged pull requests

Issues opened / closed

2 / 0

Last push

Nov 5, 2026

Open issues & PRs

From useblacksmith/setup-docker-builder (Blacksmith's public Docker layer-caching action (Unlicense)). Counts cover the last 90 days unless noted.

What the community says

Hacker News & GitHub issues · Aug 17, 2026 – Nov 15, 2026

Most of the discussion is Hacker News commenters recommending Blacksmith as a faster, cheaper home for GitHub Actions jobs, usually in threads about GitHub Actions outages. The rest is news: the Series C at a $1B valuation on 21 October 2026, and the security notice of 6 November 2026 about unauthorised access to stored CI job logs.

What people like

Faster jobs after a one-line change · 5 sources
Users describe migrating by installing the GitHub app and changing the runner label, one in about five minutes. They report roughly 2x faster runners, and one team says about 4x shorter CI times across 30–40 workflows.
HN comment 1 HN comment 2 HN comment 3
Cheap, with a generous free tier · 2 sources
Commenters call it inexpensive, and one says dozens of repositories and hundreds of builds a week have exceeded the free allowance only once in a year.
HN comment 1 HN comment 2

What people complain about

Nothing consistent enough to report.

Written by Tobias Brandt on Nov 15, 2026 after reading 10 relevant Hacker News comments, threads and GitHub issues from Aug 17, 2026 to Nov 15, 2026. Each point links to the discussions behind it, and the count shows how many sources raised it. This is a reading of public discussion, not a survey.