Last Updated: June 30, 2026
Use VirtMCU to test and simulate firmware — not to run real-world safety-critical systems, and not to clone our engine. Your code stays yours; we just run it and delete it afterward. It's a simulator provided as-is, so always validate on real hardware before you ship. If things go legally sideways, disputes are handled by arbitration rather than court, and our liability is capped. VirtMCU is in beta, so expect changes. For the vast majority of you this never matters — but the full text below is what legally controls.
This summary is for convenience only and is not itself a contract.
THESE TERMS OF SERVICE (THESE “TERMS”) SET FORTH THE LEGALLY BINDING TERMS AND CONDITIONS THAT GOVERN YOUR USE OF THE SITE AND THE SIMULATION SERVICES. BY ACCESSING OR USING THE SITE OR SERVICE (INCLUDING VIA API OR AUTONOMOUS AGENTS), YOU ARE ACCEPTING THESE TERMS (ON BEHALF OF YOURSELF OR THE ENTITY THAT YOU REPRESENT). SECTION 9 CONTAINS A BINDING ARBITRATION AGREEMENT AND CLASS ACTION WAIVER. PLEASE READ IT CAREFULLY.
The website located at https://virtmcu.com (the “Site”) and the virtual hardware emulation platform accessible via API or Model Context Protocol (MCP) (the “Service”) are copyrighted works belonging to Refract Systems, Inc., a Delaware corporation with its principal place of business in Sunnyvale, California (“Company”, “us”, “our”, and “we”).
Account Creation: In order to use certain features of the Site and Service, you must register for an account and authenticate via Google Sign-In or passwordless email verification. You represent and warrant that all registration information you submit is truthful and accurate.
Autonomous Agent & API Key Security: You are responsible for maintaining the confidentiality of your Account login information and API keys, and you are fully responsible for all activities that occur under your Account. This includes any simulation runs, compute hours, or data transfers initiated autonomously by AI agents, scripts, or integrations configured by you. You agree to immediately notify us of any unauthorized use or security breaches.
Emulation License: Subject to these Terms, the Company grants you a non-transferable, non-exclusive, revocable, limited license to access the Site and run firmware simulations solely for your own development and testing purposes.
Restrictions: You agree not to: (a) license, sell, rent, or lease the Service; (b) modify, disassemble, reverse compile, or reverse engineer any part of the VirtMCU simulation engine, orchestrator, or QEMU/QOM peripheral plugins; (c) access the Service in order to build a competitive emulator, simulator, or similar tool; (d) bypass rate limiting or security sandboxes.
Your Code & Binaries (Customer Content): You retain all rights, title, and intellectual property in any source code, config files, and compiled firmware binaries (e.g. ELF files) uploaded to the platform (“Customer Content”). These files are processed transiently in memory to run your simulations and are deleted automatically upon session termination. Each customer's workloads run in a dedicated, isolated instance within a closed, fully emulated environment (emulated CPUs, MCU peripherals, and simulated communication channels), with no connection to other customers' environments or to physical hardware.
Processing License: So that we can operate the Service, you grant Company a worldwide, non-exclusive, royalty-free, sublicensable (to our sub-processors solely to provide the Service) license to host, store, transmit, cache, compile, execute, display to you, and otherwise process your Customer Content solely to provide, maintain, secure, and support the Service. Running your firmware in our emulation environment necessarily involves reproducing and executing it; this license authorizes exactly that and nothing more. It ends when your Customer Content is deleted in the ordinary course of the Service, except that it survives as long as needed to complete an in-flight session and to retain the token-hash-keyed operational logs described in our Privacy Policy. We do not use your Customer Content to train machine-learning models, and we do not sell it.
Feedback: If you provide us with any feedback, you hereby assign to the Company all rights in such feedback, allowing us to use and exploit it in any manner we deem appropriate.
You agree to indemnify and hold the Company (and its officers, employees, and agents) harmless, including costs and attorneys' fees, from any claim or demand made by any third party due to or arising out of (a) your use of the Service, (b) your violation of these Terms, (c) your violation of applicable laws or regulations, or (d) any firmware compiled or tested on VirtMCU that is deployed to physical devices.
THE SERVICE IS PROVIDED ON AN “AS-IS” AND “AS AVAILABLE” BASIS. COMPANY (AND OUR SUPPLIERS) EXPRESSLY DISCLAIM ANY AND ALL WARRANTIES OF ANY KIND, WHETHER EXPRESS, IMPLIED, OR STATUTORY.
No Silicon Parity Guarantee: VirtMCU is a virtual emulation environment that models microcontrollers and their peripherals on a best-effort basis. It executes your real, unmodified firmware and produces deterministic, reproducible runs, but it is a model — we do not warrant that simulation behavior will match physical hardware or silicon in every scenario, and it is not a substitute for validating on real hardware before deployment.
High-Risk Activities Restriction: The Service is not designed or intended for use in connection with any situation where the failure of the simulation or the code tested could lead to death, personal injury, or severe physical or environmental damage (“High Risk Activities”). High Risk Activities include, without limitation, full or partial autonomous vehicle control, aviation or air traffic systems, nuclear facilities operation, medical life-support technology, or emergency response controllers. You agree not to use the Service in connection with any High Risk Activities.
No Physical Damage Liability: UNDER NO CIRCUMSTANCES SHALL THE COMPANY BE LIABLE FOR DAMAGE TO PHYSICAL MICROCONTROLLERS, BOARDS, MACHINERY, CYBER-PHYSICAL SYSTEMS, OR REAL-WORLD EQUIPMENT RESULTING FROM EMULATED CODE TRANSFERRED TO PHYSICAL DEVICES. All firmware must be independently tested and validated on physical hardware test benches before real-world deployment.
Acceptable Use: Your use of the Service is also governed by our Acceptable Use Policy, which is incorporated into these Terms by reference. The provisions below supplement, and do not limit, that Policy.
Rate Limiting & Keys: To guarantee service availability, we enforce rate limiting (token bucket parameters) on all API endpoints. You agree not to bypass, disable, or spam API endpoints. You are solely responsible for protecting your API keys.
Prohibited Sensitive Data: You agree not to upload, transmit, or submit to the Service any sensitive or prohibited personal information, including: credit/debit card numbers, bank account numbers, social security numbers or national ID identifiers, health data regulated by HIPAA, or special categories of personal data governed by GDPR.
Sandbox Security: You agree not to upload binaries designed to escape the virtual machine/sandbox, execute hypervisor exploits, perform Denial of Service attacks on our infrastructure, or attempt reverse-engineering of the proprietary simulation engine.
TO THE MAXIMUM EXTENT PERMITTED BY LAW, IN NO EVENT SHALL THE COMPANY (OR OUR SUPPLIERS) BE LIABLE TO YOU OR ANY THIRD PARTY FOR ANY LOST PROFITS, LOST DATA, COSTS OF PROCUREMENT OF SUBSTITUTE PRODUCTS, OR ANY INDIRECT, CONSEQUENTIAL, EXEMPLARY, INCIDENTAL, SPECIAL, OR PUNITIVE DAMAGES ARISING FROM OR RELATING TO THESE TERMS OR YOUR USE OF THE SERVICE, EVEN IF THE COMPANY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
TO THE MAXIMUM EXTENT PERMITTED BY LAW, NOTWITHSTANDING ANYTHING TO THE CONTRARY CONTAINED HEREIN, OUR AGGREGATE LIABILITY TO YOU FOR ANY DAMAGES ARISING FROM OR RELATED TO THESE TERMS WILL AT ALL TIMES BE LIMITED TO THE GREATER OF (A) THE TOTAL FEES YOU PAID US FOR THE SERVICE IN THE TWELVE (12) MONTHS PRECEDING THE EVENT GIVING RISE TO THE LIABILITY, OR (B) ONE HUNDRED US DOLLARS ($100). SOME JURISDICTIONS DO NOT ALLOW CERTAIN LIMITATIONS OF LIABILITY, SO SOME OR ALL OF THE ABOVE MAY NOT APPLY TO YOU.
All payment transactions are processed securely by Stripe, which acts as our Merchant of Record via Stripe Managed Payments. By upgrading to a paid tier, you agree to Stripe's terms and authorize recurring monthly charges to your payment method until you cancel. As Merchant of Record, Stripe collects and remits any applicable sales tax or VAT, which may be added at checkout. Cancellation and our 14-day refund eligibility exceptions are governed by our Refund Policy (virtmcu.com/refund).
These Terms will remain in full force while you use the Service. We may suspend or terminate your rights to use the Service (including your Account) at any time for any reason at our sole discretion, including for any violation of these Terms.
Arbitration Agreement: You agree that any dispute between you and the Company relating to the Service or these Terms will be resolved by binding arbitration, rather than in court, except that small claims court may be utilized on an individual basis.
Informal Dispute Resolution: Before commencing arbitration, you and the Company agree to engage in an informal video or telephonic meet-and-confer conference in a good faith effort to resolve the dispute. Notice to the Company should be sent via email to legal@virtmcu.com or by mail to the Los Angeles address listed below.
Rules & Forum: The arbitration will be conducted by JAMS in Santa Clara County, California (or by videoconference at your election). For a claimant who is a consumer, the JAMS Consumer Arbitration Minimum Standards and JAMS' consumer rules apply; otherwise the JAMS Streamlined Arbitration Rules apply. Judgment on the award may be entered in any court having jurisdiction.
Consumer Arbitration Fees: For a consumer claimant, and consistent with the JAMS Consumer Arbitration Minimum Standards, Company will pay the arbitrator's and JAMS' fees and costs above the initial small filing fee payable by the consumer (which will not exceed the amount required to file in a court of general jurisdiction).
Waiver of Jury Trial & Class Actions: YOU AND THE COMPANY WAIVE ANY CONSTITUTIONAL AND STATUTORY RIGHTS TO SUE IN COURT AND HAVE A TRIAL IN FRONT OF A JUDGE OR JURY. ALL CLAIMS MUST BE ARBITRATED ON AN INDIVIDUAL BASIS AND NOT ON A CLASS OR CONSOLIDATED BASIS.
Consumers: If you use the Service as a consumer (an individual acting outside your trade, business, or profession), nothing in these Terms excludes, restricts, or modifies any guarantee, right, or remedy that the mandatory consumer-protection law of your country of residence confers on you and that cannot lawfully be excluded (including the statutory rights of consumers in the EU, the UK, and Australia). Where your home-country mandatory law so requires, the binding-arbitration agreement, class-action waiver, and foreign-forum selection above do not apply to you and do not deprive you of access to the courts of, and the mandatory protections of, your country of residence; and the warranty disclaimers (Section 4) and liability limitations (Section 6) apply to you only to the extent that law permits.
Export Control & Sanctions: You agree not to export, reexport, or transfer, directly or indirectly, any U.S. technical data or software acquired from the Company in violation of United States export laws or regulations. You represent that you are not located in, or a national or resident of, a comprehensively sanctioned jurisdiction (currently Cuba, Iran, North Korea, Syria, and the Crimea, Donetsk, and Luhansk regions of Ukraine), and are not on any applicable sanctions list (including the OFAC SDN list).
Governing Law & Venue: These Terms are governed by the laws of the State of California, without regard to conflict-of-laws rules, and, for federal matters and the arbitration agreement, the Federal Arbitration Act. Subject to the arbitration agreement above, the exclusive venue for any permitted court proceeding is the state and federal courts located in Santa Clara County, California, and the parties consent to personal jurisdiction there. The U.N. Convention on Contracts for the International Sale of Goods does not apply.
Force Majeure: Neither party is liable for any delay or failure to perform (other than payment obligations) due to causes beyond its reasonable control, including acts of God, natural disasters, war, terrorism, civil unrest, labor disputes, governmental action, internet or utility failures, and failures of third-party hosting, network, or payment providers.
Assignment: You may not assign or transfer these Terms without our prior written consent; any attempted assignment in violation is void. We may assign these Terms in connection with a merger, acquisition, reorganization, or sale of assets. These Terms bind and benefit permitted successors and assigns.
Severability: If any provision is held unenforceable, it will be modified to the minimum extent necessary or severed, and the remaining provisions remain in full force.
Entire Agreement: These Terms, together with the Acceptable Use Policy, the Privacy Policy, the Refund & Cancellation Policy, and any Enterprise order or DPA, constitute the entire agreement between you and Company regarding the Service and supersede all prior or contemporaneous agreements on that subject. An executed Enterprise agreement controls over these Terms, which control over the incorporated policies except where a policy expressly states otherwise.
Changes to These Terms: We may modify these Terms from time to time. For material changes, we will notify you by email to your account address or by a prominent notice on the Site, and the changes take effect 30 days after notice. Non-material changes or clarifications take effect on posting. Your continued use of the Service after changes take effect constitutes acceptance.
Survival: The provisions concerning intellectual property and restrictions, Customer Content, disclaimers, limitation of liability, indemnification, prohibited data, export/sanctions, dispute resolution, the consumer carve-out, and these general terms survive termination.
Electronic Communications: Communications between you and the Company will be conducted electronically, and all electronic notices satisfy any legal requirement that such communications be in writing.
Contact & Disclosure Information:
Refract Systems, Inc.
Marcin Szczodrak
Address: 1301 N Broadway STE 98521, Los Angeles, CA 90012
Telephone: (408) 462-2874
Email: legal@virtmcu.com