AFL++ Licensing

AFL++ is licensed under the GNU Affero General Public License, version 3 or later (AGPL-3.0-or-later).

This page explains the licensing in plain language. The authoritative texts are the license files themselves (linked below).

TL;DR

• Using AFL++ under the AGPL is free and always will be. Most users need nothing more than this.
• The project as a whole is AGPL-3.0-or-later, because some AGPL-licensed files are part of the afl-fuzz fuzzer.
• Many source files are individually available under the Apache-2.0 License, while others are AGPL-3.0-or-later. Each file declares its own license in its SPDX-License-Identifier header — that header is what applies, so check the file you use and adhere to it.
• A commercial license is available for organizations that cannot or do not want to comply with the AGPL. It is not sold — you obtain it by donating to a good cause (see below). The project or its inviduals receives no money.

The three ways you can use AFL++

1. Under the AGPL-3.0-or-later (default, free)

Anyone may use, study, modify, and distribute AFL++ under the terms of the GNU AGPL-3.0-or-later. The main obligation to be aware of: if you modify AFL++ and let others interact with your modified version over a network, the AGPL requires you to offer them the corresponding source code. If that is fine for you, you are done — no payment, no donation, nothing else required.

2. Per file under Apache-2.0 (for files marked Apache-2.0)

Many AFL++ source files carry an SPDX-License-Identifier: Apache-2.0 marker and remain available under the Apache License 2.0; you may reuse those individual files in your own projects under Apache-2.0. Other files are marked SPDX-License-Identifier: AGPL-3.0-or-later. Always check the header of the file you use and adhere to the license stated there.

Note: the combined afl-fuzz program links AGPL-licensed files, so any binary or larger work that includes them is AGPL as a whole. The Apache-2.0 option applies to the Apache-2.0 files taken individually, not to the combined AGPL work.

3. Under the commercial license (optional, for companies)

If your organization cannot or does not want to comply with the AGPL, you can obtain a one-year commercial license that lets you use AFL++ without the AGPL's obligations. See the full terms in LICENSE.COMMERCIAL.

The short version:

• The project earns nothing. We do not sell licenses. Instead you donate to a good cause, and the donation is what grants the license.
• Donate EUR 20,000 (twenty thousand euros, €20,000), or the equivalent in another currency, to either the Electronic Frontier Foundation (EFF) or the Chaos Computer Club (CCC).
• Email proof of the donation (recipient, amount, date, donor) to afl@aflplus.plus.
• Your commercial license is then effective as of the donation date and lasts one year.
• When the year ends it fully expires — to keep using AFL++ you must renew (donate again), switch to AGPL compliance, or stop using AFL++.

Third-party components

AFL++ bundles third-party code that keeps its own separate license, including (non-exhaustively) xxHash (BSD-2-Clause), t1ha (Zlib), libFuzzer (Apache-2.0-with-LLVM-exception), and various git submodules. These are not relicensed and are governed solely by their own license texts. Each such file carries its own SPDX-License-Identifier.

File map

File	What it is
LICENSE	Full AGPL-3.0 text — the project's overall license
LICENSE.Apache-2.0	Full Apache-2.0 text — the license of the Apache-2.0 files
LICENSE.COMMERCIAL	The optional, donation-based commercial license
SPDX-License-Identifier: headers	Per-file license markers in the source

Questions about licensing: afl@aflplus.plus