How to stop someone else from patenting your invention, without paying for a patent
Publish it. A patent is only granted for something new, so once your invention is public, with a date that can be proven and enough detail that an expert could build it, a later patent application for the same thing should fail. This is called a defensive publication. It costs nothing on Open Prior Art, but it also means you most likely can't patent the invention yourself, and it doesn't stop anyone from using or copying it.
Why publishing works
Every patent office in the world requires an invention to be new before it grants a patent. "New" means it was not available to the public anywhere, in any form, before the application was filed. Anything that was available is called prior art.
So if you publish a clear description of your invention today, anyone who files a patent application for the same thing tomorrow should be refused, or, if their patent is granted anyway, it can later be challenged with your publication. You don't need to own anything for this to work: the publication itself does the job.
Two things decide whether a publication actually counts:
- The date. It only counts against applications filed after it became public. That is why a provable publication date matters.
- The detail. It has to describe the invention clearly enough that a skilled person could carry it out. A vague idea ("a smarter hinge") blocks very little; a description with the parts, how they connect and how it works blocks much more. See how to write a disclosure that counts.
Your four options compared
| Option | Typical cost | Stops others patenting it? | Stops others using it? | Watch out for |
|---|---|---|---|---|
| Patent it | Thousands to tens of thousands of euros over its life, more for many countries | Yes | Yes, in the countries where it is granted and kept in force | Cost, years of procedure, and you have to enforce it yourself |
| Publish it (defensive publication) | Free to low | Yes, for applications filed after your publication date | No: anyone may use it, including you | You most likely lose the right to patent it yourself |
| Keep it secret | Free | No: someone who invents it independently can patent it | Only while the secret holds | Works for recipes and processes, not for products that can be examined |
| Do nothing | Free | No | No | Someone else could patent it and stop you from using it |
If you want to use your invention freely but don't need to stop others from using it, publishing is usually the cheapest way to keep that freedom.
What publishing does not do
- It doesn't stop copying. Publishing gives no exclusive rights. Anyone can make and sell what you described.
- It doesn't reach back in time. It cannot block an application someone filed before your publication date. For that, see if someone has already filed.
- It isn't automatic. An examiner has to find your publication, or someone has to bring it up later. Clear English titles, summaries, keywords and patent classes make it far easier to find.
- It isn't a guarantee. Whether a publication counts as prior art in a particular case is decided by the patent office or court concerned.
Where to publish: the choices
Anything public can be prior art, but some places make it much easier to prove the date and much more likely that an examiner finds it.
| Where | Cost | Strengths | Weaknesses |
|---|---|---|---|
| Your blog, website or social media | Free | Fast, easy | Dates are easy to dispute, pages disappear, examiners rarely search there |
| Scientific journal or preprint server (e.g. arXiv) | Free to high | Well indexed, trusted dates | Needs a research paper, not just an invention; may be slow |
| Technical Disclosure Commons | Free | Indexable by Google Patents; established, run by bepress at Google's request | Used mostly by companies; no patent-style classes or certificate |
| Commercial databases (e.g. IP.com, Research Disclosure) | Paid | Long-established, searched by patent offices | Cost per publication |
| Open Prior Art | Free | Patent-style entries (classes, English summary, references), two independent timestamps, Internet Archive copy, certificate, original in any language | New, so not yet as well known to examiners; human review takes a few days |
You can also publish in more than one place. The earliest provable date is the one that counts.
How to do it on Open Prior Art, step by step
- Read "Before you publish". Confirm you understand that publishing is permanent and what you give up.
- Create a free account. We email you a login link; there are no passwords. Your name stays private unless you choose to show it.
- Write the disclosure in your own words: the problem, a detailed description, an example and variants, up to five drawings. The original can be in any language; add an English title and summary so examiners can find it.
- Add patent classes and known prior art. The form suggests classes that similar patents use, so your entry sits where examiners search.
- Run the completeness check and submit. The check only points out gaps; it never writes for you.
- We review and publish it. It gets a permanent number (OPA-year-number), a fingerprint, two independent timestamps and an Internet Archive copy. When the proof is complete, you get your Certificate of Publication.
If someone has already filed a patent application
A publication made after their filing date won't count against their application. But if you can show the invention was public before they filed (an old product, manual, video, article, earlier publication), you can tell the patent office:
- European Patent Office: anyone can file third-party observations on a published application, free of charge and even anonymously, and, after grant, an opposition within nine months (there is an official fee, and you become a party to the proceedings).
- United States: third parties can make a preissuance submission of prior art on a pending application, within set time limits.
These are formal procedures with their own rules. If a specific patent is in your way, it is worth talking to a patent professional.
Questions
Can I stop someone from patenting my idea without getting a patent myself?
Yes, in most cases, by publishing a clear description of it with a provable date before they file. A patent requires the invention to be new, and your publication makes it no longer new. It does not stop anyone from using the idea, including you.
Is posting my idea on my blog or social media enough?
It can count as prior art, but it is weak in practice: the date is easy to dispute, posts get deleted or edited, and patent examiners rarely search there. A registry with independent timestamps and permanent copies is much stronger evidence.
Can I still patent my invention after publishing it?
In most countries, no. Europe and China have no general grace period for your own disclosures. The US, Japan, South Korea, Canada and Australia allow 12 months, but only there. If you might want a patent, file first or get advice before publishing.
Does publishing stop others from copying my invention?
No. Publishing creates no rights. It keeps the invention free for everyone, including you, but anyone may also make and sell it.
How much does a defensive publication cost?
On Open Prior Art it is free. Commercial prior-art databases charge per publication. A patent typically costs thousands to tens of thousands of euros over its life.
Sources
- European Patent Convention, Article 54: Novelty
- European Patent Convention, Article 55: Non-prejudicial disclosures
- 35 U.S.C. 102: Conditions for patentability; novelty (USPTO, MPEP)
- Mewburn Ellis: Grace periods for disclosure of an invention before applying for a patent
- European Patent Convention, Article 115: Observations by third parties
- EPO: Third-party observations
- European Patent Convention, Article 99: Opposition
- USPTO: Preissuance submissions by third parties
- Technical Disclosure Commons: About defensive publications