ClaimMark-A Prior Art Search: find the US patents closest to your invention, before you pay to file.
A new prior art search tool from ClaimMark Inc., the company behind ClaimMark-P. Describe your invention, paste your claims, or enter a published US number, and see the closest US patents and published applications in seconds, ranked, with a record of exactly how you searched. Free for 10 searches a month.
Free: 10 searches a month, no card. Pro: $49 a month. API documentation.
Reality check: there is no point in preparing a patent application for an idea someone else has already invented. Yet many inventors skip the search, because a commissioned one costs $35 to $500 and they are sure no such product has ever been seen before. A search now is the cheapest way to find out whether you are right, and to see who your real competitors are.
Measured against the examiner's own citations
On 1,440 US patent applications filed after our search model was trained, ClaimMark's search put about twice as much of the examiner-cited prior art in its top 20 results as keyword search alone (11.4% vs 5.5%; 95% interval for the gain 1.9x–2.3x).
Examiners cite only part of the relevant prior art, so these figures measure agreement with the USPTO examiner and understate what a search finds. The method and the list of the 1,440 applications, each with its priority-date limit and the examiner-cited art it was scored against, are available on request: inquiries@claimmark.ai. How we test prior-art search.
Read the study: ten conditions and our results →What you get: three ways to search, and a record of every search.
Search by description
Paste an abstract, a summary, or a few sentences about your invention. ClaimMark-A matches by meaning as well as by wording, so related art turns up even when it uses different words. Ranked US patent families come back in seconds.
Search by claims
Paste your independent claims and see which patents and applications read closest to them.
Search by number
Enter a published US application, patent, or application number. The search runs from that document's own abstract and claims, cut off at its priority date.
The examiner check
On a number search, see which results the examiner cited, and the related art the examiner didn't. Examiner citations are recorded for patents granted from 2001 on.
Filters
Narrow by CPC class, publication dates, and grants or applications.
A search record
What you searched, the index date, the method, and every result in order. Pro exports it as a PDF or a CSV file.
Why it's different: free to start, and you can prove how you searched.
Free to start
Ten searches a month at no cost and no card. Pro is $49 a month for up to 1,000 searches, where a commissioned search typically runs $35 to $500 each.
Shows what was missed
Search from a published number and the examiner's citations sit beside the related art the examiner didn't cite.
You can prove how you searched
The same request at the same index date returns the same list. Cite it, reopen it, and repeat it.
Your idea stays yours
What you search is never used to train anything. No tracking scripts. Pro history is visible only to you, and you can delete it at any time.
Built by patent people
Made by ClaimMark Inc., the company behind ClaimMark-P, with co-founder Jürgen Vollrath, a patent attorney with more than three decades of practice.
Fresh every week
Updated weekly from the USPTO, and every search record names the date the index is updated through.
Who it's for: inventors, patent practitioners, and developers.
Inventors and founders
Check your idea before you pay to file, and find out early who is already working in your space.
Patent attorneys and agents
A fast first pass on a new matter, art for an information disclosure statement, and art the examiner didn't cite.
Developers
The same search through an API, for your own tools. The Developer plan is free for 250 calls a month.
What it doesn't cover: foreign patents, US design patents, non-patent literature, and US patents granted before 1836, apart from a few survivors.
US granted patents from 1836 onward and published applications from 2001 onward, searched by keywords, CPC classification, and semantic (meaning-based) retrieval combined. Text of patents granted before 1976 is machine-read (OCR) and may contain errors; those results are labeled. No foreign documents, no US design patents, no US patents granted before 1836 apart from a few surviving earlier patents, and no non-patent literature.
Index built from USPTO bulk data in September 2026, extended to US grants from 1836 in October 2026, and updated weekly from the USPTO; every search record names the build and the date it is updated through.
See exactly what's in the index →
A white paper you never heard of still counts against your patent, and a search can miss relevant art, including art in its coverage. Treat it as one search among those your invention needs, not as a clearance or a legal opinion.
Your searches stay yours.
What you search is never used to train or tune anything, ours or anyone else's. The API stores no query text, and Free keeps no history. Payments are handled on Stripe's own pages, so card details never reach ClaimMark. Details: privacy policy, security, and Terms of Service.
Search before you file.
Free: 10 searches a month, no card. Pro: $49 a month, with the top 100 results, history, and export. Search API: Developer free, Starter $99 a month, Scale $499 a month.