Effective date: July 4, 2026
This End-User License Agreement (the "License") is between you (an individual or a legal entity) and Seiraiyu ("Licensor") and governs your use of the RyuSim SystemVerilog simulator, including its command-line tools, runtime libraries, installers, generated simulation code templates, and accompanying documentation (collectively, the "Software"). By downloading, installing, or using the Software, you agree to this License. If you do not agree, do not install or use the Software.
In plain language: RyuSim is free for everyone — personal, academic, and commercial use alike. You may not redistribute it, reverse engineer it, or tamper with its IP-protection features. It is provided as-is, without warranty. The full terms below control.
Subject to your compliance with this License, Licensor grants you a free-of-charge, worldwide, non-exclusive, non-transferable, non-sublicensable license to install and use the Software on machines under your control, for any lawful purpose, including commercial use. The Software is licensed, not sold.
Except to the extent expressly permitted by this License or by applicable law that cannot be contractually waived, you may not:
The Software is protected by copyright and other intellectual property laws. Licensor and its licensors retain all right, title, and interest in and to the Software. No rights are granted to you other than those expressly stated in this License.
You retain all rights to the SystemVerilog designs, testbenches, and other inputs you process with the Software, and to the outputs the Software produces from them — including simulation results, waveform files, coverage reports, and generated simulation executables for your own designs. Licensor claims no ownership of your designs or outputs.
The Software incorporates or depends on third-party components (for example, the
Slang SystemVerilog frontend and other open-source libraries) that are licensed under
their own terms. Those terms apply to those components, and nothing in this License
limits your rights under them. Applicable third-party notices are included with the
Software distribution as THIRD_PARTY_NOTICES.txt in the release
bundle.
The Software can decrypt and simulate IP protected under IEEE 1735. Such IP remains the property of its respective owners and is governed by the license terms between you and the IP owner. You are solely responsible for ensuring you are authorized to use any protected IP you simulate.
If you submit bug reports, suggestions, or other feedback, you grant Licensor a perpetual, irrevocable, worldwide, royalty-free license to use that feedback for any purpose, without obligation to you.
Licensor may provide updates, which are governed by this License unless accompanied by separate terms. Licensor may modify or discontinue the Software, its distribution channels, or any related services (including the download and key-broker services) at any time. Pre-release ("alpha") builds are provided for evaluation and may be unstable.
THE SOFTWARE IS PROVIDED "AS IS" AND "AS AVAILABLE," WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, ACCURACY OF RESULTS, OR UNINTERRUPTED OPERATION. YOU ARE RESPONSIBLE FOR VERIFYING SIMULATION RESULTS BEFORE RELYING ON THEM, INCLUDING FOR TAPE-OUT OR OTHER PRODUCTION DECISIONS.
TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, LICENSOR WILL NOT BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES, OR ANY LOSS OF PROFITS, REVENUE, DATA, OR GOODWILL, ARISING OUT OF OR RELATING TO THE SOFTWARE OR THIS LICENSE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. LICENSOR'S TOTAL AGGREGATE LIABILITY UNDER THIS LICENSE WILL NOT EXCEED ONE HUNDRED U.S. DOLLARS (US$100). NOTHING IN THIS LICENSE EXCLUDES LIABILITY THAT CANNOT BE EXCLUDED UNDER APPLICABLE LAW.
This License is effective until terminated. It terminates automatically if you breach it. Upon termination, you must stop using the Software and delete all copies. Sections 3 through 7 and 9 through 15 survive termination.
You must comply with all applicable export control and sanctions laws in connection with your use of the Software.
Licensor may publish revised license terms for future versions of the Software, including terms under which future versions or related services are offered for a fee. The terms that accompanied (or were in effect for) the version you downloaded continue to govern that version.
Licensor may assign this License, and its rights and obligations under it, in whole or in part — including in connection with a merger, acquisition, or sale of assets — without notice or consent. This License binds and benefits any successor or assignee. You may not assign this License without Licensor's prior written consent.
This License is governed by the laws of the jurisdiction in which Seiraiyu is established, without regard to its conflict-of-laws rules.
Licensing questions — including redistribution or bundling permission — can be raised on the ryusim-validation issue tracker or via the Support page.