The Four Freedoms Test for Real Open Source
Judge whether software is truly open source by four inviolable user freedoms, not marketing claims.
- Difficulty
- Easy
- Time to result
- ~days to results
- Steps
- 4
- Confidence
- 95%
A concrete test for classifying whether a license is genuinely open source: the software must grant four freedoms — to use for any purpose, to inspect the code, to change it, and to redistribute changes. If any freedom carries a permission gate (e.g. a monthly-active-user cap), it fails. Mullenweg uses this to argue Meta's Llama is 'fake open source' despite being freely downloadable.
Origin
The Four Freedoms are the formal definition from Richard Stallman and the Free Software Foundation, codified in the GNU General Public License (GPL) that WordPress uses; the Open Source Initiative (OSI) maintains the parallel formal definition. Mullenweg applies them as a live diagnostic test.
Core principles
- 01Freedom is measured by the absence of permission gates, not by price or availability
- 02A single conditional clause (e.g. a MAU threshold requiring a separate license) voids open-source status
- 03'Freely downloadable' is not the same as 'free'
- 04The GPL's copyleft 'hack' forces the same freedoms to pass downstream to anyone you share with
- 05Defer to the formal OSI/FSF definition rather than a company's self-labelling
How to run it
- 1
Test freedom to use for any purpose
Check whether you can use the software for anything without asking permission. If usage above any threshold requires a license from the vendor, this freedom fails.
Pro tip Look specifically for monthly-active-user or revenue caps buried in the license — that is the classic tell.
Watch out Ambiguous thresholds (e.g. 'active registered users' vs 'visitors reached') create traps where you can't even tell if you comply.
- 2
Test freedom to inspect
Confirm you can open the hood, see every line of code, and audit how the software actually works.
- 3
Test freedom to change
Confirm you are allowed to modify the code for your own use.
- 4
Test freedom to redistribute changes
Confirm you can share your modified version. Under copyleft/GPL, verify the same freedoms must pass to whoever receives it.
Pro tip A copyleft (viral) license like the GPL guarantees downstream freedom; permissive licenses like MIT do not enforce it.
Watch out If redistribution is blocked or gated, the license is proprietary regardless of the 'open source' label on the box.
In the wild
Llama can be downloaded and run locally, but its license requires a separate license from Meta once you exceed roughly 750 million monthly active users. Mullenweg notes his own products reach billions of visitors monthly, so even the threshold definition is ambiguous.
→ He publicly classifies Llama as not open source ('false profit') despite Meta being a major genuine open-source contributor via React and PHP engine work.
Common mistakes
Equating downloadable with open source
People assume that because they can download and run a model locally it is open source; the permission gate above a usage threshold means they are still at the whims of the vendor, which violates the freedom to use for any purpose.
Trusting the label over the license
Companies call software 'open source' for marketing or regulatory reasons; the only reliable check is the formal OSI/FSF definition applied clause by clause, not the vendor's claim.
Is it for you?
Best for
Developers, founders, and PMs deciding whether to build a business on top of a third-party model or platform and needing certainty they won't be gated later.
Not ideal for
Situations where you only need the software short-term or below any threshold and never intend to redistribute — the distinction may not matter to you.
From the transcript
“the freedom to use the software for any purpose so you can use it for anything whether I agree with you or not”
“the GPL has a fun little hack where if you share them you have to provide those same freedoms to who you share it with”
“there's a clause in it that says if you're above a certain threshold of monthly active users I forget what it is like it's big…”
“that does not give you the freedom to use a software for any purpose right if at some point you have to ask for permission…”
From the episode
The creator of WordPress opens up about becoming an internet villain, why he’s taking a stand, and the future of open source
Matt Mullenweg (founder and CEO, Automattic)