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Open-source software we build on

The Terraform side of runners.io is built on two open-source projects, both under the Mozilla Public License 2.0. This page says who wrote them, what we took, and what the licence asks of us.

The projects

otf

What it is to us
The code our Terraform engine was forked from, written by Louis Garman and contributors. We forked it on 16 July 2026, at commit cf7f7836.
Licence
MPL-2.0

OpenTofu

What it is to us
What executes every plan and apply.
Licence
MPL-2.0

Substantial parts of our Terraform engine come from otf. We keep its commit history, so that who wrote what stays traceable, and we keep its copyright and licence notices.

What MPL-2.0 asks of a hosted service

The Mozilla Public License 2.0 is a file-level, or weak, copyleft licence. In plain terms:

  • It applies to the files it covers, not to everything they are combined with. Code of our own in other files can carry other terms.
  • Its duty to share source is triggered by distributing the software to someone. If you hand someone the software in executable form, you must make the source of the covered files available to them, under the same licence.
  • Running the software as a service for other people is not, in the licence’s text, distributing it. Unlike the AGPL, MPL-2.0 has no clause that treats network use as distribution, so a hosted service does not by itself have to publish its source.
  • Anyone who distributes the software must keep its copyright and licence notices. Credit is a condition, not a courtesy.

So the source duty bears on any copy of the software that is handed to someone, not on running it for them. We keep the notices either way.

What we do beyond the minimum

  • The whole engine is licensed MPL-2.0, in its entirety. We have not split it into an open part and a proprietary part, and none of its features is held back under other terms.
  • We monetise the service, which is running it well, and not withheld code.
  • We keep otf’s full history and its notices, and we credit it here, on the Terraform page and in the Terraform documentation.

Where the source is

The source of our Terraform engine is not public today. It lives in a private repository, and we are not promising a date here. A licence that applies to the software does not by itself make a hosted service publish its source, and we would rather say where things stand than imply otherwise.

Not affiliated

runners.io is not affiliated with, endorsed by, or sponsored by HashiCorp, Inc. or IBM Corp. TERRAFORM is a registered trademark of HashiCorp, Inc. Any reference to Terraform on this site is nominative, describing compatibility only.

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