Short answer: yes — you can include MIT-licensed code in a GPL project. But the question is usually being asked from the wrong direction. The harder, more common question is: can I include GPL code in my MIT-licensed project?
License compatibility isn't a symmetric relationship. When people say "MIT is compatible with GPL," they mean: code under MIT can be combined with code under GPL into a larger work, and that larger work can be distributed under GPL. The MIT code keeps its MIT notice; the combined work as a whole is GPL.
The reverse is not true. You cannot take GPL code, combine it with your MIT code, and ship the result under MIT. The GPL's copyleft clause requires the combined work to be distributed under GPL. You're free to do that — the GPL allows it — but the result is a GPL'd project, not an MIT one.
This is why the FSF describes some licenses as "GPL-compatible": those licenses allow code under them to be combined into a GPL work without conflict. MIT, BSD-2-Clause, BSD-3-Clause, ISC, X11, Apache-2.0, and Zlib are the common ones.
The reason most engineers Google "is MIT compatible with GPL" is because they're shipping a closed-source or permissively-licensed product, and they want to know if a given GPL-licensed dependency is safe to include.
The honest answer for most B2B SaaS:
Older debates around GPL focused on whether dynamic linking creates a "derivative work" subject to GPL. The conservative reading (and FSF's position): yes, both static and dynamic linking create a combined work that the GPL's source-disclosure clause applies to. The looser reading (Linus Torvalds and others): dynamic linking against a stable interface is its own work. Most legal teams take the conservative reading.
For modern web tooling — npm, pip, cargo — there's no meaningful linking distinction. If a GPL package ends up in your node_modules and gets bundled into the JavaScript you ship to users, you're combining it.
A package licensed as GPL-2.0-or-later means the upstream lets you use it under GPL-2.0 or any later version. Practically that means GPL-3.0 today and whatever comes next. Some legal teams flag "or later" because it's an open-ended commitment to terms that don't exist yet. From a software-engineering standpoint it rarely matters, but if your legal team is conservative, surface it.
LGPL is what Apache and Mozilla licenses look like in spirit but written with GPL's structure. It permits combination with non-GPL code via dynamic linking without triggering full copyleft. Most procurement teams treat LGPL as low-risk, similar to MIT/Apache, but some still flag it because of the linking subtleties above.
If the SBOM you send a customer contains GPL-licensed packages, label them clearly:
The most common "trap" we see in dependency trees: a GPL-2.0-or-later package buried five levels deep, brought in by a popular permissively-licensed library that quietly took it as a transitive dep. LicenseHound's CLI walks the full transitive tree explicitly so these don't get hidden in the noise.
| Combining direction | Result |
|---|---|
| MIT into GPL project | OK; output is GPL |
| GPL into MIT project (distributed) | Output must be GPL — usually a problem for closed-source products |
| GPL into closed-source SaaS (network access only) | Plain GPL: typically OK. AGPL: not OK without source disclosure. |
| GPL build tool, not shipped in product | OK |
| Apache-2.0 into GPLv2 (without "or later") | Incompatible — Apache patent clause conflicts with GPLv2's terms |
| Apache-2.0 into GPLv3 | OK — GPLv3 was specifically designed to fix the Apache incompatibility |
Compatibility tables are fine as a starting point but no substitute for reading the relevant license texts (or having someone read them) when something nontrivial is at stake.