USPTO database search, a practical guide to every database

The USPTO does not run one search box for everything. Over the last few years it replaced most of its older tools: Patent Public Search replaced PatFT and AppFT in 2022, Patent Center fully replaced EFS-Web and Private and Public PAIR in November 2023, and the Assignment Center replaced EPAS and the old Assignment Search site. Bookmarks and internal manuals written before these changes often point to systems that no longer exist.

The table below is a quick map. The rest of this guide covers each system, what it is good for, and where its data stops.

Patent Public Search is the full text search tool for US granted patents and pre-grant publications, and it also includes older patents available through optical character recognition. It has a Basic Search for quick lookups by number, inventor or a few keywords, and an Advanced Search modeled on the tools examiners use, with field searching, Boolean operators and proximity operators such as ADJ, NEAR, WITH and SAME.

Advanced Search is where serious work happens. You can restrict terms to claims, abstract or title, combine keyword sets with Cooperative Patent Classification codes, limit by date ranges, and save search histories so each step of a strategy can be reviewed later. Results open in a document viewer with the full text and page images side by side, and you can tag and annotate documents during review.

There is one important limit. The assignee field in Patent Public Search is the assignee printed on the patent at issue, or the applicant at publication. It is never updated when a patent is sold, a company merges or a lender takes a security interest. It is the right field for finding what a company filed, and the wrong field for deciding what a company owns today.

• Use classification codes to catch documents that use different vocabulary.
• Search the claims field when the question is about scope.
• Treat the assignee field as historical, not current.
• Save the search history so a colleague can reproduce the result.

Patent Center is organized around the application number. Anyone can search it without signing in for published applications and issued patents and see the bibliographic data, continuity, the full list of documents and transactions, fees and patent term adjustment. Applicants and their practitioners who sign in can also see their unpublished applications and file new documents.

The documents and transactions list is the image file wrapper: every office action, response, interview summary, notice of allowance, petition decision, terminal disclaimer and certificate of correction. For litigation, licensing and valuation work, this is where you find the arguments and amendments that shape claim scope, and the continuity data that determines the earliest filing date and the expected expiration.

Patent Center also shows maintenance fee activity for issued patents. Maintenance fees fall due 3.5, 7.5 and 11.5 years after grant, with a six month grace period with surcharge. A patent whose fee was not paid expires at the end of the grace period, and that single fact can change the value of an entire diligence exercise. For a walk through the steps on one application, see our patent application lookup guide.

• Confirm status from the most recent document, not just the status line.
• Download the file wrapper for any asset that matters to a transaction.
• Check terminal disclaimers, since they tie expiration to another patent.
• Review the fee history before reporting a patent as in force.

Ownership is recorded separately from examination. The Assignment Center is where assignments, security agreements, releases, name changes, mergers and other documents affecting title are recorded and searched. Each recorded document is identified by a reel and frame number, and the search shows the conveyance type, the parties, the execution and recordation dates and the patents and applications the document covers.

Recording matters because of 35 U.S.C. 261. An assignment must be in writing, and an assignment that is not recorded within three months of its date, or before a later purchase, is void against a later purchaser for value without notice. Recording is still ministerial: the USPTO does not examine whether the document is valid, whether the signer had authority, or whether the chain makes sense. It indexes what is submitted.

That is why reading the Assignment Center well takes practice. The same company may appear under several names. A security interest may be recorded but never released. An inventor may never have signed an assignment. A merger may be recorded against only part of a portfolio. Search by patent number and by application number, then read the documents in date order, and you will see the chain of title rather than a list of names. Our page on the USPTO assignment database explains the record structure in more detail.

• Search both the patent number and the application number.
• Read conveyance types, not only party names.
• Match each security interest with a release.
• Check that every inventor appears as an assignor somewhere in the chain.

The USPTO Open Data Portal at data.uspto.gov is the home for structured patent data. It provides patent file wrapper data, including bibliographic data, transaction histories and continuity, through search pages and an API, and it hosts bulk data products that used to be spread across separate download sites. Assignment data is also available in bulk.

The Open Data Portal is the right tool when a question covers hundreds or thousands of assets: every application filed by a company, every patent in a technology class, every transaction recorded in a period. It is less convenient for reading a single file, where Patent Center's document viewer is faster. Teams that run the same analysis every quarter usually start here.

Bulk data has its own pitfalls. Party names in assignment records are free text and are not normalized, so a company can appear in dozens of variations. Dates come in several formats. A conveyance recorded against a hundred patents appears once per property. Anyone building a portfolio view needs to clean names and group documents before the data says anything reliable.

• Use the API for repeatable queries on file wrapper data, or the USPTO assignment API from Assignee when you need the assembled owner of record per patent.
• Use bulk files for portfolio and market level analysis.
• Normalize party names before counting assets per owner.
• Keep the reel and frame for each record so results can be checked.

Global Dossier gives access to the file histories of related applications at participating patent offices, including the European Patent Office, the Japan Patent Office, the China National Intellectual Property Administration and the Korean Intellectual Property Office, alongside the USPTO file. It is the quickest way to see what examiners abroad cited and how the applicant amended claims in each jurisdiction.

The Patent Trial and Appeal Board publishes decisions and records for ex parte appeals and for AIA trials such as inter partes review and post-grant review. If a patent has been challenged, these records can matter as much as the original prosecution history, since claims may have been cancelled or confirmed. Search PTAB records by patent number before relying on the claims as issued.

Trademarks run on their own systems. The trademark search system replaced TESS in November 2023, TSDR shows status and documents for each application or registration, and trademark assignments are recorded and searched through the Assignment Center as well. Do not expect patent tools to show trademark data or the reverse.

• Use Global Dossier to compare examination of the same family across offices.
• Check PTAB records for any patent that may be challenged or licensed.
• Keep trademark and patent searches separate, even for the same owner.

Most errors in USPTO database search come from stopping in the first system that returns a result. A sound routine moves from text to status to ownership, and records a source for each fact. Start in Patent Public Search to identify the documents, move to Patent Center for status, family and fees, then to the Assignment Center for the chain of title, and use the Open Data Portal when the list grows beyond what you can read by hand.

Document what you did. Note the date of each search, the query or numbers used and the system that returned the answer. Records change: assignments are recorded weeks or months after they are signed, fees are paid or missed, and new continuations are filed. A diligence memo that says when the record was checked is worth far more than one that does not.

Finally, decide in advance which questions need a person to read the underlying documents. A missing inventor assignment, a security interest without a release or an owner name that does not match the seller in a deal are judgment calls, and they are the points where patent due diligence earns its fee.

• Text first, then status, then ownership.
• Record the date and source of every fact.
• Rerun ownership checks close to signing or closing.
• Escalate anomalies in the chain of title for legal review.

Several mistakes recur across firms and deal teams. The first is reporting the face-of-patent assignee as the owner. The second is searching only the patent number in the Assignment Center and missing documents recorded against the application before grant. The third is treating a status line as final without checking for revivals, terminal disclaimers or certificates of correction.

Third party tools add their own layer of risk. Google Patents, commercial platforms and spreadsheets in data rooms are useful starting points, but they summarize USPTO records with their own logic and update schedules. When the answer goes into a contract, a valuation or a court filing, go back to the USPTO record and cite the document. For the related task of finding prior art across USPTO and foreign databases, see our guide to prior art search.

• Do not confuse filer with owner.
• Do not trust one number to retrieve the whole chain.
• Do not rely on summaries when the record is available.