USPTO Patent Assignment Search Scraper

Search the official USPTO Assignment Center for patent ownership-transfer records — every recorded assignment, security interest, merger, and name change on a US patent since August 1980. No login, no API key, no cookies required.

What is a patent assignment?

When a patent's ownership changes hands — an inventor assigns rights to their employer, a startup is acquired, a patent is used as loan collateral, or a company changes its legal name — the transaction is recorded with the USPTO's Assignment Center. This actor pulls those public records directly from the same database that powers assignmentcenter.uspto.gov.

What you can search

• By patent number — full assignment history for one issued patent
• By application number — full assignment history for one filed application
• By publication number — pre-grant publication number lookup
• By PCT number — international (PCT) application number lookup
• By international registration number — WIPO-linked national-phase lookup
• By reel/frame — the exact USPTO recordation identifier for one assignment document
• By assignee (owner) name — every assignment where a company/person received rights, e.g. Google LLC
• By assignor (seller) name — every assignment where a company/person gave up rights, e.g. an inventor or an acquired company
• By correspondent name — every assignment filed through a specific law firm or agent

Output fields

Each row is one patent-assignment record:

Field	Description
patentNumber, applicationNumber, publicationNumber, pctNumber, internationalRegistrationNumber	Whichever identifiers exist for the underlying patent/application
inventionTitle, inventors[]	Bibliographic details of the underlying patent
filingDate, issueDate, publicationDate	ISO YYYY-MM-DD dates
assignors[]	{ name, entityNumber, executionDate, acknowledgedDate } — who gave up rights, their order among co-assignors, and when they signed
assignorNames[]	Flat list of assignor names
assignees[]	{ name, entityNumber, address, city, state, stateCode, zipCode, country, countryCode } — who received rights; stateCode/countryCode are USPTO's standardized short codes (US state abbreviation / ISO-3166 alpha-2)
assigneeNames[]	Flat list of assignee names
correspondentName, correspondentAddress	Law firm / agent of record on the filing
conveyanceText, conveyanceCode	Type of transaction and its official USPTO code, e.g. "ASSIGNMENT OF ASSIGNOR'S INTEREST" (23), "SECURITY INTEREST" (27), "MERGER" (28), "CHANGE OF NAME" (33) — see the full list under conveyanceType below
assignmentSequence	This assignment's position in the patent's full recordation history (1 = earliest)
isDeleted, deletionNote	Whether USPTO has flagged this specific recordation as later superseded/corrected, and its note (only present on exact-identifier modes)
reelNumber, frameNumber	USPTO's official recordation identifier
recordationDate, mailDate, receiptDate, assignorExecutionDate	ISO YYYY-MM-DD dates
pageCount, attorneyDocketNumber, domesticRepresentative	Filing metadata, when present
documentUrl	Direct PDF of the recorded assignment document — omitted when USPTO has no scanned image on file for that recordation
sourceUrl	Link back into the USPTO Assignment Center for this record
recordType, scrapedAt	Always "patentAssignment" and the UTC scrape timestamp

Fields that USPTO doesn't have data for on a given record are simply omitted — no null/"N/A" placeholders.

Input

Field	Type	Applies to	Description
mode	select	—	Which search axis to use (see list above)
patentNumber	string	byPatentNumber	e.g. 7379963
applicationNumber	string	byApplicationNumber	e.g. 09615663
publicationNumber	string	byPublicationNumber	e.g. 20140053053
pctNumber	string	byPctNumber	e.g. PCT/US21/36002
internationalRegNumber	string	byInternationalRegNumber	WIPO international registration number
reelNumber / frameNumber	string	byReelFrame	e.g. 69252 / 524
assigneeName	string	byAssigneeName	Case-insensitive substring match
assignorName	string	byAssignorName	Case-insensitive substring match
correspondentName	string	byCorrespondentName	Case-insensitive substring match
executionDateFrom / executionDateTo	date (YYYY-MM-DD)	all modes	Restrict to assignments the assignor(s) signed (executed) in this window
recordationDateFrom / recordationDateTo	date (YYYY-MM-DD)	all modes	Restrict to assignments USPTO officially recorded in this window (distinct from execution date)
filingDateFrom / filingDateTo	date (YYYY-MM-DD)	all modes	Restrict to assignments whose underlying patent/application was filed in this window
mailDateFrom / mailDateTo	date (YYYY-MM-DD)	exact-identifier modes	Restrict to assignments USPTO mailed a recordation notice for in this window
conveyanceTypeContains	string	all modes	Case-insensitive substring filter on the transaction type
conveyanceType	select	exact-identifier modes	Restrict to one official USPTO conveyance/transaction type (19 official types, e.g. Assignment, Security interest, Merger, License, Change of name)
maxItems	integer	all modes	Hard cap on emitted records (1–1000)
proxyConfiguration	proxy	all modes	Optional — USPTO does not block datacenter IPs; used only as an automatic fallback

Example: full assignment history of a patent

{
  "mode": "byPatentNumber",
  "patentNumber": "7379963",
  "maxItems": 50
}

Example: every patent Google LLC has acquired since 2020

{
  "mode": "byAssigneeName",
  "assigneeName": "Google LLC",
  "executionDateFrom": "2020-01-01",
  "maxItems": 100
}

Example: everything a specific law firm has filed

{
  "mode": "byCorrespondentName",
  "correspondentName": "Fish & Richardson",
  "maxItems": 100
}

Example: only one specific conveyance type on a patent, recorded in a given year

{
  "mode": "byPatentNumber",
  "patentNumber": "6285999",
  "conveyanceType": "39",
  "recordationDateFrom": "2002-01-01",
  "recordationDateTo": "2002-12-31",
  "maxItems": 50
}

FAQ

Do I need a USPTO account or API key? No. Patent assignment search is public. USPTO only requires an account to file a new assignment, not to search existing ones.

Why is my assignee/assignor/correspondent search capped at 100 results? USPTO's own name-search API returns a maximum of ~100 rows per query with no further pagination. Narrow your search with an execution-date range, or use one of the exact-identifier modes (patent/application/publication/PCT number, reel/frame) which support full pagination.

What does "reel/frame" mean? It's USPTO's internal filing identifier for one recorded assignment document — the paper-based equivalent of a page number in a giant ledger. Every recorded assignment has a unique reel and frame.

Can I download the actual assignment document? Yes — every record includes a documentUrl pointing directly to the scanned PDF USPTO has on file.

Is this the same as trademark assignment search? No — this actor covers patents only. Trademark ownership records live in a separate USPTO database.

Why doesn't conveyanceTypeContains or conveyanceType narrow my assignee/assignor/correspondent search? USPTO's name-search API doesn't return a conveyance/transaction type field at all (only the exact-identifier lookups — patent/application/publication/PCT number, reel/frame — do). When conveyance data isn't available for a record, the filter passes it through rather than silently hiding it.

Why doesn't mailDateFrom/mailDateTo narrow my assignee/assignor/correspondent search? Same reason — USPTO's mailroom notification date is only returned by the exact-identifier lookups, not the name-search API. recordationDateFrom/recordationDateTo has the same limitation for name searches (executionDateFrom/executionDateTo and filingDateFrom/filingDateTo work everywhere, since those dates come from fields present in both endpoints).

What is isDeleted? USPTO occasionally flags a previously recorded assignment as superseded — usually because a corrective assignment was filed to fix an error. isDeleted (and the accompanying deletionNote, when USPTO supplies one) surfaces that flag; it's only available on exact-identifier lookups.

Data source

All data comes directly from USPTO's public Assignment Center (assignmentcenter.uspto.gov), the official successor to the legacy "Patent Assignment Search" and "Assignments on the Web" tools. Records cover patent assignments recorded from August 1980 to the present.