What is relicensing?

Definition

Relicensing is the act of changing the license under which a software project is offered. The copyright holder, usually the company or foundation that owns the project, decides that future versions will ship under different terms, and from that point new releases carry the new license. In open source, the relicensing that matters to enterprises is a specific kind: the move away from an OSI approved open source license, such as Apache 2.0 or the Mozilla Public License, toward a source available license such as the Business Source License or the Server Side Public License. Source available is not the same as open source. The code remains visible, but the new license restricts how it may be used, most often by limiting competitive production use, and these licenses are not OSI approved.

Why projects relicense

The driver is almost always commercial. A company that funds the development of a widely adopted open source project watches others, particularly large cloud providers, build profitable hosted services on that software without funding its development. Relicensing to a source available license is the lever the project owner uses to restrict that competitive use while keeping the source visible to ordinary users. The recent wave of changes followed this logic. As of August 2023 HashiCorp moved Terraform, Vault, Consul, Nomad, and Packer to the Business Source License, and IBM later acquired HashiCorp. As of March 2024 Redis moved to a dual source available model. Elasticsearch and Kibana moved to the Server Side Public License and the Elastic License in 2021, and MongoDB moved to the SSPL in 2018. Each change spawned a community fork: OpenTofu for Terraform, Valkey for Redis, and OpenSearch for Elasticsearch.

Why it matters to enterprises

The reason relicensing belongs on every risk map is that it reaches software you already run. The versions you adopted before the change generally stay under their original license, which can feel reassuring, but the protection is thin. You stop receiving new versions, security patches, and features under the old terms. To stay current and supported you must accept the new license, move to a community fork, or change software entirely. Each path has a cost, and the cost lands on software that is already in production carrying real workloads. A relicense is therefore not a future risk to monitor but a present one to size, especially when the affected component sits deep in a dependency tree where no one is watching its license.

The full treatment of how a change propagates through an estate, and what to do in the first weeks after one lands, lives in the pillar on license change and relicensing.

Related terms

Relicensing is best understood alongside the license families it moves software toward. The two most common destinations are covered in the glossary entries on the Business Source License and the Server Side Public License. The broader category these belong to is explained in source available license. For the surrounding vocabulary, browse the full open source license risk glossary.