What "Free Open Source" Actually Means and How to Tell
"Free open source" combines two separate claims: free refers to price (you pay nothing to download or use it), while open source refers to the source code being available under a license that lets you inspect, modify, and redistribute it. A program can be one without the other. To verify both, look for a public source repository, an explicit license file, and build instructions — not just a "free download" button. FrostWire is a useful example: its site describes it as free with no subscriptions required, and it also lists Open Source Development and names specific licenses (GNU GPL and Apache) for its components.
Free vs. open source: two different questions
These terms answer different questions, and mixing them up is the main source of confusion.
| Term | Question it answers | What it does NOT tell you |
|---|---|---|
| Free | What does it cost? | Whether you can see or change the code |
| Open source | Can I access, modify, and redistribute the code? | Whether the software costs money |
So "free but not open source" (freeware, ad-supported apps, trials) and "open source but paid" (paid support, hosted versions, commercial add-ons) are both common and legitimate. "Free open source" means both conditions hold at once.
What a real open-source license gives you
An open-source license is what makes the "open" part enforceable. It grants permissions and sets conditions. Two licenses referenced on FrostWire's site illustrate the range:
- GNU GPL — you can use, study, modify, and redistribute the software, but derivative works generally must be released under the same license (a "copyleft" condition). This keeps downstream versions open.
- Apache License — also permits use, modification, and redistribution, but is more permissive: it does not require derivative works to use the same license, and it includes an explicit patent grant.
The practical takeaway: "open source" does not mean "no rules." The license tells you what you're allowed to do with the code, especially if you plan to modify it or ship it inside your own product.
How to verify a "free open source" claim
You can check these signals yourself in a few minutes:
- Find the source repository. Look for a link to a code host (GitHub, GitLab, SourceForge, or a project's own repo). A download page alone is not evidence.
- Locate the license file. Repositories normally include a
LICENSEfile. Read which license it is — GPL, Apache, MIT, and so on — because the terms differ. - Check for build instructions. A
READMEor build guide explaining how to compile from source shows the code is actually usable, not just posted. - Confirm the free claim separately. Check whether downloads, features, or accounts are gated. FrostWire's page states it is free and that no subscriptions are required, and offers downloads for Windows, Mac, Linux, and Android.
If a product says "open source" but you can't find a repository or license, treat the claim as unverified.
Worked example: FrostWire
FrostWire describes itself as a free BitTorrent client, video downloader, and media player. On the "open" side, its site links to Open Source Development and names GNU GPL and Apache Licensed components (including jlibtorrent/libtorrent, written in Java and C++). On the "free" side, it states the software is free with no subscriptions required and provides direct downloads across platforms.
That combination — a stated license plus a no-cost download — is what "free open source" looks like when both parts are actually present. Note that the site also accepts donations; a donation request does not contradict either claim, since neither "free" nor "open source" rules out voluntary support.
Quick checklist
- Free = price. Open source = code access and license terms. They are independent.
- Read the specific license (GPL vs. Apache vs. MIT) before you modify or redistribute.
- Verify with three artifacts: a source repository, a license file, and build instructions.
- A "free download" button proves nothing about openness; a repository without a license leaves your rights unclear.