Concept renderOpen source hardware is hardware whose design files are published so anyone can study, modify, make and sell it. The license on those files sets what you owe when you ship. A strongly reciprocal license such as CERN-OHL-S can require you to publish your own design, while permissive licenses mostly ask you to keep notices.
Most connected devices reuse something open: a reference schematic, a footprint library, a sensor breakout or a vendor SDK. Each comes with a license that decides what you must publish, which notices you keep and what your company can own. This guide is an engineering team's reading of the license texts linked below, as of November 2026. It is not legal advice, so have a lawyer confirm how these texts apply to your product.
What is open source hardware?
The Open Source Hardware Association (OSHWA) publishes a Statement of Principles 1.0 and a Definition 1.0, as of November 2026. The principles say open source hardware is hardware whose design is made publicly available so that anyone can study, modify, distribute, make and sell the design or hardware based on it, with the source in the preferred format for making changes (OSHWA definition).
The definition then sets twelve criteria for a license. Four of them matter most to a device maker:
- Documentation. The hardware must be released with documentation that includes design files.
- Scope. The documentation must clearly specify which portion of the design, if not all, is released under the license. A product can be partly open.
- Free redistribution. The license may not stop anyone from selling or giving away the documentation.
- Attribution. The license may require derived documents and device copyright notices to credit the licensors.
The definition describes the files and the rights in them. Whether you must publish your own design depends on the license on the files you reuse.
What a license can and cannot control
The OSHWA FAQ says useful or functional objects are excluded from copyright in the US and many other countries, while the design files are likely protected by copyright, and that functional objects can be protected by patents (OSHWA FAQ). The US Copyright Office says a registration for a technical drawing covers only the original expression in it and does not apply to the underlying invention (Circular 33), as of November 2026. The license binds you when your team copies or modifies the files: section 2.1 of each CERN-OHL v2 variant says that by exercising any right it grants, you accept its terms.
How do the main open source hardware licenses differ?
Strongly reciprocal licenses pass their terms on to the larger design. Weakly reciprocal ones stop at a documented interface. Permissive ones ask for notices and allow closed derivatives. The OSHWA FAQ lists the CERN license, TAPR OHL and CC BY-SA among copyleft licenses, and Solderpad among permissive ones. CERN's own v2 texts add a permissive variant, CERN-OHL-P. The table summarizes each text as of November 2026.
| License | Type | What you must do when you ship | What can stay outside it | Source |
|---|---|---|---|---|
| CERN-OHL-S v2 | Strongly reciprocal | Give each recipient the Complete Source or its location (4). Covered files inside a larger work make the whole work covered source (3.2), licensed under CERN-OHL-S (3.3(d)). | Available Components, such as a documented part you can buy (3.3(d)). | CERN-OHL-S v2 text, as of November 2026 |
| CERN-OHL-W v2 | Weakly reciprocal | Share the Complete Source of the covered design and your changes (4.1). The product may carry your own terms if they leave the covered source rights intact (4.3). | External Material that connects only through a documented interface described in the covered source (1.8, 4.2). | CERN-OHL-W v2 text, as of November 2026 |
| CERN-OHL-P v2 | Permissive | Keep the notices, add a dated notice describing your changes (3.3), and make sure product recipients can reach the applicable notices (4). | Your changes may go out under other terms if you follow 3.3 and include the license (3.4). | CERN-OHL-P v2 text, as of November 2026 |
| TAPR Open Hardware License v1.0 | Reciprocal | Include the documentation with products, or make it available without charge for at least three years to anyone who asks. License your changes under the OHL. | Software and firmware are outside its scope. | TAPR OHL page, as of November 2026 |
| Solderpad Hardware License 2.1 | Permissive (listed so by OSHWA) | It wraps Apache 2.0. Give recipients the license, mark changed files, keep notices and any NOTICE file (Apache section 4). | Works that only link to or interoperate with the licensed work are not derivative works under SHL 2.1. | Solderpad SHL 2.1 page, as of November 2026 |
| Creative Commons BY-SA | Copyleft (listed so by OSHWA) | Creative Commons does not recommend its licenses for hardware or software. | CC licenses do not license patent or trademark rights. | Creative Commons FAQ, as of November 2026 |
Section numbers refer to the CERN-OHL v2 texts. The Solderpad row relies on the Apache License 2.0 text, which SHL 2.1 extends to hardware rights such as design rights and mask works.
What do you owe when you ship a product built on an open design?
The duties start when you convey the source or a product to someone else. Before that point, section 5 of CERN-OHL-S and -W allows you to pass covered source to an outside firm doing development, testing or quality work on your behalf. The terms must stop that firm from using the source for itself or passing it to anyone but you. As we read it, development work done for you does not by itself trigger publication.
Once you ship, check these items for every open design you reused. They follow the license texts as of November 2026.
- Source delivery. CERN-OHL-S and -W require you to give each recipient the Complete Source or tell them its Source Location. TAPR OHL lets you instead make the documentation available without charge for at least three years to anyone who asks.
- Notices. Every CERN-OHL variant requires you to keep notices and add a dated note describing your changes. TAPR asks you to pass on all the materials you received, list your changes in a text file such as CHANGES.TXT, and include before and after versions of each file you modified. Apache 2.0, and so Solderpad, requires a copy of the license and any NOTICE file.
- Marking on the product. If a CERN-OHL-S or -W notice says so, the product must visibly and securely display the Source Location on itself, its packaging or its documentation.
- No contract can narrow the license. Section 2.3 of each CERN-OHL v2 variant says you shall not try to restrict, by contract or otherwise, the rights it grants to other licensees.
Firmware and SDK licenses
Firmware has its own licenses. Espressif states that ESP-IDF is licensed under Apache 2.0 and lists third-party components under BSD, MIT, Apache 2.0, CC0 and other terms, with source file headers taking precedence over its summary. It also lists third-party software compiled into the mask ROM of its chips (ESP-IDF copyrights page), as of November 2026. One firmware image can carry many licenses, each with its own notice terms, and the list belongs in your SBOM. Our SBOM and source-file handover checklist covers what that file should hold.
Can your company own the IP in a product that uses open source hardware?
Yes, for the parts your developer created and has the right to transfer. The outside parts stay under their own licenses. As of November 2026, CERN-OHL-S 3.3(d) keeps Available Components under their own licenses, and CERN-OHL-W does the same for External Material. A development contract that assigns IP to you cannot pull those parts out of their licenses, and section 2.3 forbids trying. You own what was written for you, and you hold a license, with conditions, for what was reused.
Common plans, mapped to the license texts:
| Your plan | What to do | Basis, as of November 2026 |
|---|---|---|
| Keep your board design closed and owned by your company | Keep strongly reciprocal sources out of the files you plan to keep private. Permissive sources can be reused with their notices. | CERN-OHL-S 3.2 and 4; CERN-OHL-P 3.3 and 3.4 |
| Reuse a small block, such as a charger or antenna section, from an open design | Under CERN-OHL-S, your whole board becomes covered source. Under CERN-OHL-W, keep the block behind a documented interface so the rest can be External Material, and confirm with counsel. | CERN-OHL-S 3.2; CERN-OHL-W 1.8, 4.2 |
| Publish your own design as open source hardware | Pick one license, state which part of the design it covers, and keep a public location you expect to last at least three years. | OSHWA definition, Scope; CERN-OHL-S 1.9 Source Location |
| Use the open project's name or logo on your box | The license gives you the design rights it names. Names and marks need their own permission. | Apache 2.0 section 6; CERN-OHL-S and -W 8.2; CC FAQ |
| Put the OSHWA certification mark on the product | Make every part you control open, use chips with fully accessible and shareable datasheets, register each product that bears the mark, and reaffirm each year. | OSHWA certification requirements |
| Sue someone over a patent that reads on the open design | Under all three CERN-OHL v2 variants, filing that claim ends your rights under the license. Under Apache 2.0, it ends the patent licenses granted to you for that work. Talk to patent counsel before you build on the design. | CERN-OHL-S and -W 7.2; CERN-OHL-P 6.2; Apache 2.0 section 3 |
Ask for the license inventory at every gate, before the next design freeze. Swapping a reciprocal block out of a design is simpler before the board layout is frozen than after. For how assignment works in a US contract with a Shenzhen team, see who owns the schematics, PCB files and firmware and how IP ownership works at Duobay.
If you want to certify as open source hardware
OSHWA runs a certification mark program. As of November 2026, its rules say all parts, designs, code and rights under the creator's control must be open, third-party components such as chips must have fully accessible and shareable datasheets, and each unique product bearing the mark must be registered. The certification lasts one year, and the certified party must reaffirm compliance to keep it (OSHWA certification requirements). A chip whose datasheet sits behind an NDA can block certification, so check it during part selection.
What should you ask your hardware team before reusing an open design?
Take this list to your team and to any outside firm that hands you design files.
- Which files in our design came from an outside project, library or reference design, and what license does each one carry?
- Is any of it under a strongly reciprocal license such as CERN-OHL-S or TAPR OHL, and does that reach the files we want to keep private?
- Where will the source be published if a license requires it, and who keeps that location up for at least three years?
- Which firmware components come from the chip vendor SDK, and does each license appear in our SBOM?
- Does any part depend on a datasheet that is only available under NDA?
- Will we file patents on this product, and has patent counsel seen the licenses of the parts we reused?
- Which rights does our development contract assign to us, and which stay with outside licensors?
Questions about open source hardware licenses
Can I sell a product built from an open source hardware design?
Yes, as of November 2026. The OSHWA definition says the license shall not restrict anyone from selling or giving away the project documentation, and the OSHWA FAQ says licenses that bar commercial use are not compatible with open source (OSHWA definition, OSHWA FAQ). What you owe when you ship depends on the license on the files you used.
Can I put a Creative Commons license on my hardware design?
Creative Commons says the only categories of work for which it does not recommend its licenses are software and hardware, and that its licenses do not license patent or trademark rights, as of November 2026 (Creative Commons FAQ). Use a license written for hardware, such as CERN-OHL v2 or Solderpad 2.1.
Does using an open design stop me from patenting my product?
The TAPR page says its license does not prohibit anyone from patenting inventions in an open hardware design, and that those who benefit from the design may not sue claiming it infringes their patents. All three CERN-OHL v2 variants end your rights under the license if you bring that kind of patent claim, and Apache 2.0 ends the patent licenses it granted you, as of November 2026 (TAPR OHL, CERN-OHL-S 7.2, Apache 2.0 section 3). This is an engineering summary, so ask patent counsel before you file.
How could Duobay help with open hardware licenses in my product?
Under a Duobay contract, IP and all source files are assigned to your company at every paid gate, and firmware source and an SBOM are delivered with them. An SBOM is a good place to list each outside component and its license so your counsel can review it. We do not publish prices. Tell us about your device to start with a free call.
Which sources does this guide use?
All pages accessed November 5, 2026. Licenses and program rules change, so re-read them before you rely on any statement.
- OSHWA, Open Source Hardware Definition 1.0: https://oshwa.org/resources/open-source-hardware-definition/ (accessed 2026-11-05)
- OSHWA, Open Source Hardware FAQ: https://oshwa.org/resources/open-source-hardware-faq/ (accessed 2026-11-05)
- OSHWA, certification requirements: https://certification.oshwa.org/requirements.html (accessed 2026-11-05)
- CERN-OHL-S v2: https://ohwr.org/cern_ohl_s_v2.txt (accessed 2026-11-05)
- CERN-OHL-W v2: https://ohwr.org/cern_ohl_w_v2.txt (accessed 2026-11-05)
- CERN-OHL-P v2: https://ohwr.org/cern_ohl_p_v2.txt (accessed 2026-11-05)
- TAPR Open Hardware License: https://tapr.org/the-tapr-open-hardware-license/ (accessed 2026-11-05)
- Solderpad Hardware License 2.1: https://solderpad.org/licenses/SHL-2.1/ (accessed 2026-11-05)
- Apache License 2.0: https://www.apache.org/licenses/LICENSE-2.0 (accessed 2026-11-05)
- Creative Commons FAQ: https://creativecommons.org/faq/ (accessed 2026-11-05)
- US Copyright Office, Circular 33, Works Not Protected by Copyright: https://www.copyright.gov/circs/circ33.pdf (accessed 2026-11-05)
- Espressif, ESP-IDF copyrights and licenses: https://docs.espressif.com/projects/esp-idf/en/stable/esp32/COPYRIGHT.html (accessed 2026-11-05)
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