# shadps4-emu License Information: GPL-2.0-or-later and REUSE Compliance Guide > Understand the shadps4-emu license: GPL-2.0-or-later with REUSE compliance. Learn about SPDX metadata and third-party component licensing for shadPS4. - Repository: [shadps4-emu/shadPS4](https://github.com/shadps4-emu/shadPS4) - Tags: license-information - Published: 2026-03-19 --- **The shadPS4 emulator is licensed under GPL-2.0-or-later for its core codebase, with comprehensive REUSE compliance ensuring every file contains SPDX metadata and all third-party components properly declare their MIT, BSD, OFL-1.1, or BSL-1.0 terms.** Understanding shadps4-emu license information is essential for developers, contributors, and redistributors working with this PlayStation 4 emulator. The project employs a dual-layer licensing strategy: the original emulator code falls under the GNU General Public License v2.0 or later, while bundled third-party libraries retain their original permissive licenses. All licensing data is machine-readable through SPDX headers and the REUSE.toml configuration file. ## Core Licensing Model of shadps4-emu The shadps4-emu license information follows a strict separation between original code and external dependencies, ensuring compliance while maximizing code reuse. ### GPL-2.0-or-later for Core Emulator Code All original source code in the `src/` directory is licensed under **GPL-2.0-or-later**. This includes critical components such as [`src/video_core/renderer_vulkan/vk_swapchain.cpp`](https://github.com/shadps4-emu/shadPS4/blob/main/src/video_core/renderer_vulkan/vk_swapchain.cpp), which contains the standard SPDX header: ```cpp // SPDX-FileCopyrightText: 2026 shadPS4 Emulator Project // SPDX-License-Identifier: GPL-2.0-or-later ``` The top-level `LICENSE` file contains the full text of GPL-2.0-or-later, establishing the legal foundation for the emulator's open-source distribution. Any modification or redistribution of the core emulator requires source code disclosure under the same license terms. ### Third-Party License Compatibility shadps4-emu integrates numerous external libraries and assets, each retaining their original licenses compatible with GPL-2.0-or-later: | Component | License | Location | |-----------|---------|----------| | **RenderDoc integration** | MIT | `externals/renderdoc/**` | | **ImGui framework** | MIT | `externals/imgui/` | | **Boost libraries** | BSL-1.0 | `externals/boost/` | | **Noto Sans JP font** | OFL-1.1 | `src/imgui/renderer/fonts/NotoSansJP-Regular.ttf` | | **Proggy Vector font** | MIT | `src/imgui/renderer/fonts/` | | **Documentation assets** | CC0-1.0 / CC-BY-4.0 | Documentation directories | The `LICENSES/` directory at the repository root contains verbatim copies of all these licenses, satisfying the REUSE requirement to provide full license texts for every SPDX identifier used in the project. ## How shadps4-emu Declares License Information The project implements the **REUSE Specification** to ensure machine-readable licensing across all files. ### The REUSE.toml Configuration File The [`REUSE.toml`](https://github.com/shadps4-emu/shadPS4/blob/main/REUSE.toml) file acts as the central licensing manifest, mapping file paths to their respective SPDX identifiers. It uses precedence rules for directories containing multiple files, such as `externals/**` and `src/imgui/renderer/fonts/**`, ensuring each third-party component retains its correct license annotation without requiring individual file headers. This configuration allows automated tools to compute the complete license set for the entire repository by reading a single manifest file rather than parsing thousands of individual headers. ### SPDX Headers in Source Files Every file in the repository contains explicit SPDX metadata. C++ source files include header comments: ```cpp // SPDX-FileCopyrightText: 2026 shadPS4 Emulator Project // SPDX-License-Identifier: GPL-2.0-or-later ``` Documentation files such as [`README.md`](https://github.com/shadps4-emu/shadPS4/blob/main/README.md) embed SPDX information in HTML comments: ```html ``` This granular declaration ensures that individual files carry their licensing terms even when distributed outside the repository context, preventing accidental license separation. ### The LICENSES Directory Structure The `LICENSES/` directory contains the complete legal texts for every license referenced in the project: - [`GPL-2.0-or-later.txt`](https://github.com/shadps4-emu/shadPS4/blob/main/GPL-2.0-or-later.txt) for the core emulator - [`MIT.txt`](https://github.com/shadps4-emu/shadPS4/blob/main/MIT.txt) for permissive third-party libraries - [`OFL-1.1.txt`](https://github.com/shadps4-emu/shadPS4/blob/main/OFL-1.1.txt) for fonts - [`BSL-1.0.txt`](https://github.com/shadps4-emu/shadPS4/blob/main/BSL-1.0.txt) for Boost components - [`CC0-1.0.txt`](https://github.com/shadps4-emu/shadPS4/blob/main/CC0-1.0.txt) and [`CC-BY-4.0.txt`](https://github.com/shadps4-emu/shadPS4/blob/main/CC-BY-4.0.txt) for documentation This structure satisfies the REUSE requirement to provide verbatim license copies while enabling automated tools to validate that every SPDX identifier has a corresponding full text file. ## Verifying shadps4-emu License Compliance You can validate the licensing status of any shadps4-emu repository clone using the official REUSE command-line tools. First, install the REUSE tool: ```bash pip install reuse ``` Run the linter to verify that every file has a valid SPDX header and that all referenced licenses exist in the `LICENSES/` directory: ```bash reuse lint ``` A compliant repository produces no errors. To generate a comprehensive license report for auditing purposes: ```bash reuse dump --format json > license-report.json ``` This command outputs a JSON file listing every SPDX identifier in the project, including GPL-2.0-or-later for core components and the various MIT, BSL-1.0, and OFL-1.1 identifiers for third-party assets. ## Key Files for License Reference When examining shadps4-emu license information, these specific paths define the legal framework: | File Path | Purpose | |-----------|---------| | `LICENSE` | Full text of GPL-2.0-or-later governing the emulator core. | | [`REUSE.toml`](https://github.com/shadps4-emu/shadPS4/blob/main/REUSE.toml) | Central manifest mapping file paths to SPDX license identifiers. | | `LICENSES/` | Directory containing verbatim copies of all third-party licenses. | | [`src/video_core/renderer_vulkan/vk_swapchain.cpp`](https://github.com/shadps4-emu/shadPS4/blob/main/src/video_core/renderer_vulkan/vk_swapchain.cpp) | Representative core file with GPL-2.0-or-later SPDX header. | | `src/imgui/renderer/fonts/NotoSansJP-Regular.ttf` | Example font file under OFL-1.1 license. | | `externals/renderdoc/**` | Example third-party MIT-licensed component. | ## Summary - **shadps4-emu uses GPL-2.0-or-later** for its core emulator code, requiring source code disclosure for redistributions. - **REUSE compliance** ensures every file contains SPDX metadata, with [`REUSE.toml`](https://github.com/shadps4-emu/shadPS4/blob/main/REUSE.toml) providing a centralized licensing map. - **Third-party components** retain their original licenses (MIT, BSL-1.0, OFL-1.1, CC0-1.0) and are documented in the `LICENSES/` directory. - **Automated verification** is available through the `reuse lint` and `reuse dump` commands to ensure ongoing compliance. ## Frequently Asked Questions ### What license is the shadPS4 emulator core released under? The core emulator code is licensed under **GPL-2.0-or-later** (GNU General Public License version 2.0 or any later version). This is declared in the top-level `LICENSE` file and in SPDX headers within each source file, such as [`src/video_core/renderer_vulkan/vk_swapchain.cpp`](https://github.com/shadps4-emu/shadPS4/blob/main/src/video_core/renderer_vulkan/vk_swapchain.cpp). Any redistribution of the emulator must include the corresponding source code under the same license terms. ### Can I use shadps4-emu code in a commercial project? Yes, the GPL-2.0-or-later license permits commercial use, but with important conditions. If you distribute the emulator or derivative works, you must provide the complete source code under GPL-2.0-or-later. Additionally, you must preserve the licenses of third-party components such as the MIT-licensed `externals/renderdoc/` or OFL-1.1 fonts in `src/imgui/renderer/fonts/`. ### How does shadps4-emu track licenses for third-party libraries? The project uses the **REUSE Specification** to manage third-party licenses. The [`REUSE.toml`](https://github.com/shadps4-emu/shadPS4/blob/main/REUSE.toml) file maps directories like `externals/**` and `src/imgui/renderer/fonts/**` to their respective SPDX identifiers (MIT, BSL-1.0, OFL-1.1). The `LICENSES/` directory contains the full text of each license, allowing automated tools like `reuse lint` to verify that every file has proper licensing metadata. ### What is the purpose of SPDX headers in shadps4-emu source files? SPDX headers make license information machine-readable and persistent. Each file contains comments like `SPDX-License-Identifier: GPL-2.0-or-later` and `SPDX-FileCopyrightText: 2026 shadPS4 Emulator Project`. This ensures that if a single file is extracted from the repository, it still carries its licensing terms. The headers also enable automated compliance checking through REUSE tools and support software composition analysis (SCA) systems.