WarpBuild vs Blacksmith for GitHub Actions runners

By Daniel Zoghalchali·Latchkey

WarpBuild vs Blacksmith is the rare pair whose rate cards match to the cent: both list Ubuntu x64 at $0.004 a minute for 2 vCPU with 8 GB, and both double it at every step up to $0.064 at 32 vCPU. The decision is therefore everything around the rate, which is where they diverge sharply: Blacksmith gives 3,000 free minutes a month and cheaper arm64, and WarpBuild sells a bring-your-own-cloud mode at $0.002 and remote Docker builders you size yourself.

Blacksmith runs managed GitHub Actions runners on its own bare metal in Ashburn, Phoenix, Amsterdam and Frankfurt. You install a GitHub App, change a label, and the product is compute plus a cache that intercepts actions/cache with a 25 GB weekly allowance per repository. Every runner card on its pricing page carries 3,000 free minutes a month.

WarpBuild runs managed runners in its own cloud, plus two things Blacksmith does not sell: remote Docker builders billed separately from 16 vCPU at $0.06 a minute to 192 vCPU at $0.88, and a BYOC mode at $0.002 a minute where runners execute inside your own AWS, GCP or Azure account. Its cache is metered rather than allowanced, at $0.20 per GB-month plus $0.0001 for every write or restore.

Every cell below was read from the vendor's own public pricing or documentation page on 20 September 2026. Where a vendor does not publish a number, the cell says "not published" instead of carrying a guess.

WarpBuild, Blacksmith and Latchkey side by side (read 20 September 2026)

The rate cards, size by size and platform by platform

This is the table both vendor pages make you click a toggle to assemble. On Linux x64 the two are identical at every published size. On arm64 they are not: Blacksmith is 17% below WarpBuild at every step, and both are below GitHub-hosted arm64 at $0.005.

Windows and macOS follow the same pattern of near-identity with one gap each. On Windows both charge $0.016 at 4 vCPU, $0.032 at 8, $0.064 at 16 and $0.128 at 32, and only Blacksmith publishes a 2 vCPU Windows runner, at $0.008. On macOS both charge $0.08 for 6 vCPU and $0.16 for 12, against GitHub-hosted at $0.062, so on Apple hardware both are a speed purchase rather than a saving. WarpBuild publishes one platform Blacksmith does not: Linux on Apple silicon, at $0.08 for 6 vCPU.

Concurrency, which is the other number to check

Nobody thinks about concurrency until a matrix sits in a queue, and this is one axis where both vendors beat the platform they replace. GitHub caps total concurrent jobs by plan and caps macOS separately and much harder, which is why a wide iOS matrix queues on Team and does not on Enterprise.

Speed

Not benchmarked yet; the runner benchmark report will replace this section. We have not run the same workload on these runners ourselves, and until we have, there is no number here worth quoting.

The cheap way to get a real answer is to point one slow job at each candidate for a week, because runner selection is per job and the Actions run log gives you the timings for free.

Cost: the same month, priced three ways

The usual workload: 10,000 Linux minutes at 2 vCPU plus 2,000 macOS minutes a month on a private repository, at the rates above.

The entire $12 difference is Blacksmith's free minutes, which is worth saying plainly: at identical rates, the only thing separating the two on this workload is an allowance. Scale the month up and the gap stays flat at $12 while both bills grow: at 50,000 Linux minutes the Linux lines are $200 against $188, on monthly totals of $360 and $348. Latchkey's own plan is $5 to $49 a month on top of that compute, and its 2,000 to 6,000 included minutes are not netted off, so the figure is gross on both counts.

The two lines that can move it are not on that table. WarpBuild BYOC at $0.002 a minute turns the Linux half into $20 of WarpBuild fees plus whatever your own cloud charges for the instances, which is the cheapest structure on this page for anyone already holding committed spend. And the cache meters run in opposite directions: 50 GB of Blacksmith sticky disk is $25 a month, while 50 GB on WarpBuild is $10 plus about $1 per 10,000 cache operations, though Blacksmith's separate 25 GB weekly actions/cache allowance is free and WarpBuild has no equivalent.

Docker builds: two different products

Both vendors accelerate Docker, and only one of them charges you separately for it. Blacksmith keeps the build on the runner and gives BuildKit a sticky disk per cache key, so the cost is the runner minute plus $0.50 per GB-month of disk. WarpBuild moves the build to a remote builder profile you choose by size, from 16 vCPU at $0.06 a minute upward, which is a second meter running alongside the runner minutes.

Their published claims differ in kind as well as in size. WarpBuild says its builders deliver "up to 50% faster Docker builds compared to traditional solutions"; Blacksmith says "Our customers have reported 2x to 40x improvements in build times". Neither is a benchmark, and the operational details matter more: WarpBuild describes its shared builder cache as eventually consistent with a 10-day TTL, and Blacksmith documents that the first Docker run is uncached and that an idle sticky disk is evicted after 7 days. Our Depot vs Blacksmith for Docker builds page works through the same trade in more detail.

Switching: the exact diff

Both are a label change after one account step, and the account steps differ in an annoying way: Blacksmith installs from the GitHub marketplace, and WarpBuild's bot has to be installed from the WarpBuild dashboard instead. After that, runner selection is per job, so the cheap way to settle this is to point two jobs in the same workflow at the two vendors for a fortnight.

 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: blacksmith-4vcpu-ubuntu-2404

   build:
-    runs-on: ubuntu-latest
+    runs-on: warp-ubuntu-latest-x64-4x

   build-arm:
-    runs-on: ubuntu-24.04-arm
+    runs-on: blacksmith-4vcpu-ubuntu-2404-arm

The verdict

With identical x64 rates at every size, this comes down to which extras you actually use. Blacksmith wins the default case: 3,000 free minutes a month, arm64 17% cheaper at every size, a 2 vCPU Windows runner WarpBuild does not publish, and a free 25 GB weekly cache allowance against a metered one. WarpBuild wins the specialized cases, and wins them decisively: BYOC at $0.002 a minute inside your own cloud, remote Docker builders you size up to 192 vCPU, and Linux on Apple silicon. Neither publishes a concurrency ceiling worth worrying about, which is a genuine improvement on GitHub-hosted for anyone whose matrices queue. Neither one repairs a job that failed for a reason unrelated to your code, so on both you keep paying for the re-run and the merge keeps waiting for somebody to notice.

Frequently asked questions

Related guides

References

• WarpBuild pricing: runners, Docker builders, BYOC and add-ons
• WarpBuild cloud runner IDs and shapes
• WarpBuild Docker builders
• Blacksmith pricing
• Blacksmith runner instance types
• GitHub Actions documentation