---
title: "What a patent cites, and who cites it"
method: GET
path: "/v1/patents/{patent_number}/citations"
tags: ["patent status"]
---

# What a patent cites, and who cites it

`GET /v1/patents/{patent_number}/citations`

## Request

- Base URL: `https://api.patentdata.ai`
- URL: `https://api.patentdata.ai/v1/patents/{patent_number}/citations`
- Auth: one of:
  - API key in header `X-API-KEY`
  - HTTP bearer

Answers: what prior art is on this patent's front page, and which later patents cite it. `backward` is the front-page list grouped by what was cited — `patents` (US, canonical numbers), `publications` (US pre-grant, US20130157853A1), `foreign` (country + number as printed), `npl` (non-patent literature text) — each with `category` (examiner | applicant | other, with `category_detail` for other) and the cited document's `date` at the precision USPTO prints (usually a month), plus `count` / `examiner_count` / `applicant_count`. `forward` is every loaded grant citing this patent number, newest number first: [{patent_number, grant_date, title, categories}] with `count` (distinct citing grants) and `next_cursor` (famous patents have thousands; page with `limit`/`cursor`). A reference USPTO printed unreadably is kept verbatim with a `defect` note. `direction` = both | backward | forward. Coverage is the weekly grant files loaded: a `forward.count` is complete for those weeks only, and `backward` is null with `detail` naming the covered dates when the patent's own grant file is not loaded. Citations of the patent's pre-grant publication are not folded in. Costs 1 request per 100 citation rows returned.

## Path parameters

- `patent_number` string, required: US patent number without commas; design/plant/reissue prefixes allowed (D912345, PP12345, RE48123).

## Query parameters

- `direction` string: both | backward | forward.
- `limit` integer: Page size. Each 100 rows returned costs 1 request unit.
- `cursor` string, nullable: Opaque cursor from a previous response's next_cursor. Omit for the first page.

## Response `200`

Successful Response

- unknown

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/patentdata/apis/patent-status-api.md) · [All operations](https://skmtc.dev/patentdata/apis/patent-status-api/llms.txt) · [OpenAPI document](https://skmtc.dev/patentdata/apis/patent-status-api/revisions/320133a82b42?raw)