head to head · open source
Harness vs mill
Harness has 38,798 GitHub stars, 3,451 forks, 106 open issues and last shipped yesterday. mill has 2,801 stars, 449 forks, 272 open issues and last shipped yesterday. Harness leads on adoption by 1,285% (38,798 vs 2,801 stars). Harness is written in Go under Apache-2.0; mill is written in Scala under MIT. Harness has attracted 9% as many forks as stars, mill 16%. Harness was the more recently maintained of the two, and both are self-hostable with no licence fee.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Harness | mill | |
|---|---|---|
| GitHub stars | ★ 39K | ★ 2.8K |
| License | Apache-2.0 | MIT |
| Written in | Go | Scala |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 3.5K | ⑂ 449 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Harness if
- You weight community size — 39K stars and counting
- You want the Apache-2.0 license terms
- Your stack matches Go
- You value the larger contributor base for long-term maintenance
pick mill if
- You want the mill feature set and don't need the biggest community
- You prefer the MIT license terms
- Your stack matches Scala
- You evaluated both and mill fits your workflow better
About Harness
Harness Harness Open Source is an open source development platform packed with the power of code hosting, automated DevOps pipelines, hosted development environments (Gitspaces), and artifact registries. Overview Harness Open source is an open source development platform packed with the power of code hosting, automated DevOps pipelines, Gitspaces, and artifact registries. Running Harness locally The latest publicly released docker image can be found on harness/harness. To install Harness yourself, simply run the command below. Once the container is up, you can visit in your browser. The Harness image uses a…
read the full Harness overview →
About mill
= image:website/docs/logo.svg[title=Mill Logo] Mill: A Better Build Tool for Java, Scala, & Kotlin :mill stable version: 1.1.9 :link github: :link current doc site: :link mill moduledefs: // customize appearance on GitHub :idprefix: :idseparator: :toc: :toc placement: preamble ifndef::env github[] :icons: font endif::[] ifdef::env github[] :caution caption: :fire: :important caption: :exclamation: :note caption: :paperclip: :tip caption: :bulb: :warning caption: :warning: endif::[] link:changelog.adoc[image: Central Version]] Mill is a build tool that improves upon the tools traditionally used in the JVM…
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Frequently asked questions
Is Harness or mill more popular?
Harness has 38,798 GitHub stars and mill has 2,801. Harness has the larger community by that measure.
Are Harness and mill free?
Both are open source. Harness is licensed under Apache-2.0 and mill under MIT. Neither carries a licence fee.
What is the difference between Harness and mill?
Harness is written in Go and mill in Scala. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Harness or mill?
Choose Harness if you want the larger community (38,798 stars) or its Apache-2.0 licence terms. Choose mill if its feature set, stack or MIT licence fits better. Both are self-hostable.