Moving from the PatentsView API

To move a script or client from the PatentsView API to PatentRef, change the base URL from https://search.patentsview.org to https://patentref.io and add a PatentRef key in the X-Api-Key header. A Free key is at /api/v1/meta/signup/.

PatentRef answers the PatentSearch v1 grammar of the USPTO's PatentsView API, which the USPTO paused on 2026-03-20: the same paths, the same q, f, s and o parameters, the same response shape and error forms, from PatentRef's own snapshot of the USPTO data. The few places where an answer differs are listed under known differences.

What to change

Base URL: https://search.patentsview.org becomes https://patentref.io. The paths stay: /api/v1/patent/, /api/v1/inventor/ and the rest, including /api/v1/patent/otherreference/, upstream's path before its release 2.2.0, which answers as /api/v1/patent/other_reference/ does.
Key: get a Free key at /api/v1/meta/signup/ and send it in the same header, X-Api-Key. A PatentsView key does not work here.
Nothing else: q, f, s and o, the response shape (error, count, total_hits and the records under the endpoint's key) and the error forms are the same.

The PatentsView code examples notebook

In PatentSearch/0-patentsearch-api-demo.ipynb of PatentsView-Code-Examples, set api_key to a PatentRef key and base_url = "https://patentref.io". Every other cell runs as written: GET with the parameters as JSON text, POST with the parameter dictionary as the body (with or without the trailing slash), the detail route api/v1/patent/D345393/, and the inventors group unpacked with pandas. Every path of its endpoint table answers, api/v1/patent/otherreference included (the CPC class and subclass, USPC main class, WIPO and pre-grant ones with their documented 501). Its related-entity example queries inventors.inventor_country for "UK", which matches nothing here or upstream: the field holds ISO two-letter codes, so the United Kingdom is "GB" (grammar, Country codes). Its response_key() rule (the plural of the last path part, with ipcr for ipc and wipo for wipo) gives the key of every endpoint here:

Endpoint	Response key
`api/v1/assignee`	`assignees`
`api/v1/cpc_class`	`cpc_classes`
`api/v1/cpc_group`	`cpc_groups`
`api/v1/cpc_subclass`	`cpc_subclasses`
`api/v1/g_brf_sum_text`	`g_brf_sum_texts`
`api/v1/g_claim`	`g_claims`
`api/v1/g_detail_desc_text`	`g_detail_desc_texts`
`api/v1/g_draw_desc_text`	`g_draw_desc_texts`
`api/v1/inventor`	`inventors`
`api/v1/ipc`	`ipcr`
`api/v1/location`	`locations`
`api/v1/nber_category`	`nber_categories`
`api/v1/nber_subcategory`	`nber_subcategories`
`api/v1/patent`	`patents`
`api/v1/patent/attorney`	`attorneys`
`api/v1/patent/foreign_citation`	`foreign_citations`
`api/v1/patent/other_reference`	`other_references`
`api/v1/patent/rel_app_text`	`rel_app_texts`
`api/v1/patent/us_application_citation`	`us_application_citations`
`api/v1/patent/us_patent_citation`	`us_patent_citations`
`api/v1/pg_brf_sum_text`	`pg_brf_sum_texts`
`api/v1/pg_claim`	`pg_claims`
`api/v1/pg_detail_desc_text`	`pg_detail_desc_texts`
`api/v1/pg_draw_desc_text`	`pg_draw_desc_texts`
`api/v1/publication`	`publications`
`api/v1/publication/rel_app_text`	`rel_app_texts`
`api/v1/uspc_mainclass`	`uspc_mainclasses`
`api/v1/uspc_subclass`	`uspc_subclasses`
`api/v1/wipo`	`wipo`

The CPC class and subclass, USPC main class and WIPO lookups may answer 501 in a build that lacks their data set (known differences); each patent carries the same facts in its cpc_current, cpc_at_issue, uspc_at_issue and wipo groups.

Client libraries and MCP servers

rOpenSci patentsview (R): version 1.0.0 builds its URLs in get_base(). Until a release takes a base URL setting, replace that function for the session: assignInNamespace("get_base", function(endpoint) sprintf("https://patentref.io/api/v1/%s/", endpoint), ns = "patentsview"), and set PATENTSVIEW_API_KEY to a PatentRef key.
mustberuss/PatentsView-APIWrapper (Python): the URL in safe_patentsview_post() becomes https://patentref.io/api/v1/ plus the entity.
patent-mcp-server 0.7.0: set PATENTSVIEW_BASE_URL=https://patentref.io and PATENTSVIEW_API_KEY; no code change. Later releases return a fixed answer from their PatentsView tools.

Responses carry X-Data-Version; cache by it, and check it when a paged walk spans a weekly refresh.