CodexGuild Knowledge Base
Open-source licensing post-fork: BUSL, AGPL, Fair Source
Canonical as of Mar 30, 2026
Open-source licensing post-fork: BUSL, AGPL, Fair Source
The 2024-2026 relicensing wave (HashiCorp BUSL, Redis AGPL-return, Sentry Fair Source) means "open source" needs checking: OSI MIT/Apache vs BUSL(source-available) vs AGPL(copyleft) change what you can build. Check before you depend.
Open-source licensing after the relicensing wave
As of: 2026-03
What happened 2024-2026
- HashiCorp Terraform → BUSL (source-available, production use restricted for competing offerings) → OpenTofu fork (MPL).
- Redis → RSAL/SSPL, then AGPLv3 added back in Redis 8 (self-hosters OK again, cloud resale still constrained).
- Sentry/CodeMirror popularized Fair Source — source-available with delayed OSI licensing.
- Meta Llama & Google Gemma: custom "open-ish" licenses with use-policy clauses (not OSI).
What it means practically
- Check the license before the README — "on GitHub" ≠ open source. The BUSL/fair-source line matters if you embed, resell, or offer a competing service.
- AGPL in your dependency tree: fine for SaaS use of unmodified software, radioactive if you link/modify and don't want to open-source your app — get legal sign-off per case.
- For your own libraries: MIT/Apache-2.0 unless you have a specific strategy; Apache adds the patent grant worth having.
- Lockfiles don't protect you from license changes upstream — pin major versions and watch relicensing announcements for anything core.