Contributor licence agreement
Draft dated 25 September 2026. This agreement has not been through legal review, has no contractual effect, and cannot be accepted or signed yet. Until it is in force and a repository checks for it, PROOF repositories licensed under the Functional Source License accept first-party commits only.
PROOF publishes the software customers run with Liskov (the runtime helper,
the runtime SDK, the CLI and its plugins, the self-custody signer, and the
GitHub actions) under the Functional Source License, Version 1.1, with
Apache 2.0 as the future licence (FSL-1.1-Apache-2.0). Each version of
that software becomes available under the Apache License, Version 2.0 on its
change date, two years after it is released.
A patch licensed only under the Functional Source License would not carry that future licence with it. This agreement lets PROOF offer your contribution on the same terms as the rest of the repository, now and after the change date. You keep the copyright in your contribution.
There are two forms:
- the individual agreement, for a person contributing on their own behalf; and
- the entity agreement, for a company or other organisation whose employees or contractors contribute on its behalf.
In both, PROOF, we and us mean Moose Labs Ltd, company number 11435949, a private limited company registered in England and Wales, trading as PROOF.
Individual contributor agreement
This agreement is between you, the individual named when you accept it (you), and PROOF. It applies to every Contribution you Submit, now or later.
Definitions
Contribution means any original work of authorship, including any change or addition to existing work, that you Submit to PROOF for inclusion in a Project.
Project means a software repository that PROOF owns or manages and licenses under the Functional Source License.
Submit means to send a work to PROOF or its representatives in any form, including a pull request, a patch, an issue comment containing code, or a message to a PROOF mailing list or tracker, unless you mark it conspicuously as "Not a Contribution".
1. Copyright licence
You grant PROOF, and every recipient of software PROOF distributes, a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable licence to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense and distribute your Contributions and those derivative works.
That licence includes the right to license your Contributions:
- under the Functional Source License, Version 1.1, as part of a Project; and
- under the Apache License, Version 2.0, or any other future licence the Functional Source License names for a version of a Project that includes your Contributions, from that version's change date.
2. Patent licence
You grant PROOF, and every recipient of software PROOF distributes, a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent licence to make, have made, use, offer to sell, sell, import and otherwise transfer your Contributions.
The licence covers only the patent claims you can license that are necessarily infringed by your Contributions alone, or by your Contributions combined with the Project you Submitted them to. If anyone begins patent litigation, including a cross-claim or counterclaim, alleging that your Contribution or a Project containing it infringes a patent, every patent licence granted to them under this agreement for that Contribution or Project ends on the date the litigation is filed.
3. Your authorship
You confirm that:
- each Contribution is your original creation, and you are legally entitled to grant the licences in this agreement;
- if your employer or anyone else has rights in what you create, including intellectual property you create in your work, they have given you permission to make your Contributions on their behalf and to grant these licences, or have waived their rights in those Contributions; and
- no Contribution includes anything that another person owns unless you identify it as described in section 4.
4. Work that is not yours
If you want to Submit work that is not your original creation, submit it separately from any Contribution. Identify it as not your own, name its source and state every licence and other restriction you know applies to it, including any patent, trademark or licence agreement. Mark it conspicuously as "Submitted on behalf of a third party: [name]".
5. No other obligations
PROOF is not required to use, merge or publish any Contribution. Except as stated in this agreement, you provide your Contributions "as is", without warranties or conditions of any kind, and you have no duty to support them.
6. Keeping this true
You will tell PROOF if you learn that any statement in this agreement has become inaccurate.
Entity contributor agreement
This agreement is between the company or other organisation named when it is accepted (you, including every entity that controls, is controlled by or is under common control with it), and PROOF. It applies to every Contribution Submitted on your behalf by a person you authorise, now or later.
The person accepting it for you confirms that they have authority to bind you.
Definitions
Contribution, Project and Submit have the meanings in the individual agreement, except that a Contribution is Submitted by one of your Authorised Contributors on your behalf.
Authorised Contributor means an employee, contractor or other individual you designate to PROOF as authorised to Submit Contributions on your behalf. You keep that list current by telling PROOF whenever you add or remove someone.
1. Copyright licence
You grant PROOF, and every recipient of software PROOF distributes, a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable licence to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense and distribute your Contributions and those derivative works.
That licence includes the right to license your Contributions:
- under the Functional Source License, Version 1.1, as part of a Project; and
- under the Apache License, Version 2.0, or any other future licence the Functional Source License names for a version of a Project that includes your Contributions, from that version's change date.
2. Patent licence
You grant PROOF, and every recipient of software PROOF distributes, a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent licence to make, have made, use, offer to sell, sell, import and otherwise transfer your Contributions.
The licence covers only the patent claims you can license that are necessarily infringed by your Contributions alone, or by your Contributions combined with the Project they were Submitted to. If anyone begins patent litigation, including a cross-claim or counterclaim, alleging that your Contribution or a Project containing it infringes a patent, every patent licence granted to them under this agreement for that Contribution or Project ends on the date the litigation is filed.
3. Your authorship
You confirm that:
- each Contribution is an original creation of an Authorised Contributor made for you, and you are legally entitled to grant the licences in this agreement;
- each Authorised Contributor is authorised by you to Submit Contributions on your behalf; and
- no Contribution includes anything that another person owns unless it is identified as described in section 4.
4. Work that is not yours
If an Authorised Contributor wants to Submit work that is not your original creation, they submit it separately from any Contribution. They identify it as not your own, name its source and state every licence and other restriction you know applies to it, including any patent, trademark or licence agreement. They mark it conspicuously as "Submitted on behalf of a third party: [name]".
5. No other obligations
PROOF is not required to use, merge or publish any Contribution. Except as stated in this agreement, you provide your Contributions "as is", without warranties or conditions of any kind, and you have no duty to support them.
6. Keeping this true
You will tell PROOF if you learn that any statement in this agreement has become inaccurate, including when an Authorised Contributor leaves or is no longer authorised.