The Rise of "Source Available" vs True Open 2026
The Rise of "Source Available" vs True Open Source
You can see the code. You can self-host it. But is it open source? The rise of "source available" licenses is blurring the line — and it matters more than you think.
The Spectrum
| Category | Can Read Code | Can Modify | Can Distribute | Can Compete | Examples |
|---|---|---|---|---|---|
| Proprietary | ❌ | ❌ | ❌ | ❌ | Slack, Notion |
| Source Available | ✅ | ✅ (limited) | ⚠️ (restrictions) | ❌ | Sentry (BSL), MongoDB (SSPL) |
| Open Source (copyleft) | ✅ | ✅ | ✅ (share alike) | ✅ | Mattermost (AGPL), Linux (GPL) |
| Open Source (permissive) | ✅ | ✅ | ✅ | ✅ | React (MIT), Kubernetes (Apache) |
What Makes Something "True" Open Source?
The Open Source Initiative (OSI) defines open source through the Open Source Definition. Key requirements:
- Free redistribution — Anyone can share it
- Source code available — Must include or make available
- Derived works allowed — Can modify and distribute modifications
- No discrimination — Can't restrict who uses it or for what purpose
- No restriction on other software — Can't require that other software also be open
OSI-Approved vs Not
| License | OSI-Approved | Type |
|---|---|---|
| MIT | ✅ | Open Source |
| Apache-2.0 | ✅ | Open Source |
| GPL-3.0 | ✅ | Open Source |
| AGPL-3.0 | ✅ | Open Source |
| BSL-1.1 | ❌ | Source Available |
| SSPL | ❌ | Source Available |
| Elastic License 2.0 | ❌ | Source Available |
| Confluent Community License | ❌ | Source Available |
Why Companies Are Choosing Source Available
The Timeline
| Year | Company | Change | Reason |
|---|---|---|---|
| 2018 | MongoDB | AGPL → SSPL | AWS offering managed MongoDB |
| 2019 | Elastic | Apache → SSPL + Elastic License | AWS Elasticsearch Service |
| 2021 | Grafana | Apache → AGPL | Preemptive protection |
| 2023 | HashiCorp | MPL → BSL | "Vendors taking without contributing" |
| 2023 | Sentry | BSL | Sustainable business protection |
| 2024 | Redis | BSD → RSALv2 + SSPL | Cloud provider competition |
| 2024 | Terraform | BSL | (continued from HashiCorp change) |
The Pattern
1. Company creates open source tool (MIT/Apache)
2. Tool becomes popular
3. Cloud providers offer managed version
4. Company can't compete with cloud providers' scale
5. Company changes license to restrict cloud providers
The Business Source License (BSL) Explained
BSL is the most common source-available license. Here's how it works:
Years 1-3: Source Available
- You can read, modify, and self-host
- You CANNOT offer it as a competing service
- The "Additional Use Grant" defines what's allowed
Year 4+: Becomes Open Source
- Automatically converts to Apache-2.0 (or similar)
- All restrictions lifted
BSL in Practice
| What You Can Do | What You Can't Do |
|---|---|
| Self-host for your company | Offer a competing managed service |
| Modify the code | Sell hosted access to the software |
| Contribute patches | Build a SaaS product using it as core |
| Use internally (any purpose) | Resell as-is |
Who Uses BSL
| Project | BSL Since | Converts To | Additional Grant |
|---|---|---|---|
| Sentry | Launch | Apache-2.0 | Can use for internal business |
| CockroachDB | 2019 | Apache-2.0 | Non-commercial use |
| MariaDB MaxScale | 2017 | GPL | Non-production use |
| Outline | Recent | Apache-2.0 | Self-hosting for any purpose |
Does It Matter for Self-Hosters?
For Most Users: No
If you're self-hosting for your team or company:
| Question | BSL Answer | True OSS Answer |
|---|---|---|
| Can I self-host? | ✅ Yes | ✅ Yes |
| Can I modify the code? | ✅ Yes | ✅ Yes |
| Can I use for my business? | ✅ Yes | ✅ Yes |
| Can I see the source code? | ✅ Yes | ✅ Yes |
| Is it free? | ✅ Yes | ✅ Yes |
When It Does Matter
| Situation | Impact |
|---|---|
| You want to offer it as a managed service | ❌ BSL won't allow this |
| You want to fork and build a competing product | ❌ BSL won't allow this |
| You want to embed it in commercial software | ⚠️ Depends on the Additional Use Grant |
| You want long-term guarantee of openness | ⚠️ BSL converts in 3-4 years, but company can change terms |
| You contribute code | ⚠️ Your contribution is under BSL, not true OSS |
The Community Response
Forks
When companies changed licenses, the community responded with forks:
| Original | License Change | Fork | Fork License |
|---|---|---|---|
| Elasticsearch | → SSPL | OpenSearch (AWS) | Apache-2.0 |
| Terraform | → BSL | OpenTofu (Linux Foundation) | MPL-2.0 |
| Redis | → RSALv2 + SSPL | Valkey (Linux Foundation) | BSD-3 |
Result: The community now has true open source alternatives, but the ecosystem is split.
The Debate
Pro Source Available:
"We gave away our software for free. AWS made billions offering it as a service and contributed nothing back. BSL lets us survive while keeping the code visible."
Pro True Open Source:
"If you benefited from open source community contributions under an open license, changing the license is a betrayal of trust. Fork it."
The Pragmatist:
"I just want to self-host software that works. I don't care about the license as long as I can run it on my server."
How to Evaluate Licenses as a User
Quick Decision Framework
| Your Use Case | MIT/Apache | AGPL | BSL | SSPL |
|---|---|---|---|---|
| Self-host for team | ✅ | ✅ | ✅ | ✅ |
| Modify for internal use | ✅ | ✅ | ✅ | ✅ |
| Offer as managed service | ✅ | Share mods | ❌ | Share everything |
| Embed in proprietary product | ✅ | Consult lawyer | Depends | ❌ |
| Fork and compete | ✅ | ✅ (share alike) | ❌ | ❌ |
| Long-term freedom guarantee | ✅ | ✅ | ⚠️ (converts eventually) | ⚠️ |
Our Recommendation
- Prefer true open source (MIT, Apache, GPL, AGPL) when alternatives exist
- BSL is acceptable for self-hosting — it works the same as OSS for most users
- Be cautious of SSPL — the restrictions are broad and vague
- Always check the license before building on top of a project
The Bottom Line
"Source available" licenses like BSL are a pragmatic response to cloud providers freeloading on open source. For self-hosters, the practical difference is minimal — you can still see the code, modify it, and run it.
But the philosophical difference matters: true open source guarantees your freedom to use software however you want. Source available gives you most of those freedoms with a business-protection carve-out.
When choosing tools for your stack, prioritize true open source where possible. But don't let a BSL license stop you from using a great tool — especially when it converts to open source after 3-4 years.
Business Impact: How License Changes Affect Adopters
When a project changes its license from open source to source-available, the impact on existing users depends on their use case and the specific terms of the new license.
For most self-hosters — individuals and organizations running software for their own use — license changes from MIT/Apache to BSL or SSPL are typically non-events. The new license still permits self-hosting for internal use. The change targets cloud providers who were running the software as a competitive commercial service, not individuals running a personal Nextcloud instance or a company running internal tooling. If you're self-hosting for your team's use, you're almost never the target of these license restrictions.
For companies that have built products or services on top of the open-source project, the impact is more significant. A startup that integrated a BSL-licensed library into their SaaS product needs legal review. The BSL's "Additional Use Grant" (the carve-out that allows specific uses) is defined per project and can be narrow. Redis's BSL change in 2024 specifically excluded using Redis as part of a commercial "database service" — a company building a Redis-compatible cloud database product was directly targeted. A company using Redis as the session store for their internal app was not affected.
For open source projects that consume the changed dependency, the license change can force a fork or dependency swap. This is exactly what happened with Elasticsearch: when AWS's integration with Elasticsearch conflicted with Elastic's commercial interests, Elastic changed the Elasticsearch license to SSPL (which requires open-sourcing the entire service stack that deploys it — impractical for AWS). AWS forked Elasticsearch as OpenSearch under the Apache-2.0 license, which is now the maintained community alternative. The fork outcome gave the community an actually open alternative, but it also split the ecosystem.
For end users of SaaS products built on these tools, the impact is invisible — they use the product regardless of what licenses its dependencies carry. The license drama is an infrastructure concern for the companies building on top of these tools.
Which Tools Have Gone Source-Available (and When)
The license change wave has affected several prominent tools in the developer and infrastructure space. Understanding the timeline helps evaluate the stability of license commitments in tools you're considering.
HashiCorp changed Terraform and Vault from MPL-2.0 to BSL 1.1 in August 2023. The BSL version of Terraform forbids competitors from offering Terraform as a managed service. The community response was OpenTofu — a fork of Terraform under MPL-2.0, now part of the Linux Foundation. HashiCorp (now IBM after the acquisition) still develops Terraform, but the open source community has a maintained fork.
Redis changed its license from BSD-3-Clause to RSALv2 (Redis Source Available License) and SSPL in March 2024. Valkey, a community fork under BSD-3-Clause, launched immediately and became the default Redis alternative in many Linux distributions. Redis 8.0 later added some open-source licensed modules back in a hybrid approach.
Elasticsearch and Kibana moved from Apache-2.0 to SSPL in January 2021. OpenSearch (AWS-led fork) launched as the Apache-2.0 alternative and has become the maintained community version.
MongoDB moved to SSPL in 2018, which prompted major Linux distributions to remove MongoDB from their package repositories. Many self-hosters migrated to PostgreSQL for document-style workloads or to alternative databases.
Notably, many tools have maintained their open-source licenses despite commercial pressure: PostgreSQL (BSD), SQLite (public domain), Linux (GPL-2.0), nginx (BSD), and the majority of the tools covered at OSSAlt. The tools that have changed licenses are often those that faced direct competition from hyperscaler cloud services — a specific competitive dynamic that doesn't affect most self-hosted tools.
For the debate around AGPL specifically (a genuinely open-source license that companies sometimes misidentify as "source available"), see The AGPL License Debate: Why OSS Companies Are Choosing It. For how open core business models work alongside open licensing, see How the Open Core Model Works: Free vs Paid. For the current landscape of open source adoption trends, see State of Open Source Alternatives 2026.
Check the license of every open source alternative at OSSAlt.