# x402stock Patent Assignment Lookup

> x402stock Patent Assignment Lookup is a paid API for AI agents from x402stock.xyz, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-22).

Retrieves USPTO patent assignment records for a given US patent application number

## Facts

- Endpoint: GET https://x402stock.xyz/api/v1/patent/%7Bapplication%7D/assignments?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-22
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402stock-patent-assignment-lookup-d317862f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jkQLEXDjdI8vTCz_-j353

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability x402stock-patent-assignment-lookup-d317862f
```

Example prompt: Can you look up the patent assignment records for US patent application number 18687455 and tell me who the current assignee is and when the assignment was recorded?

## When to prefer this

Use this endpoint when you need structured, machine-readable USPTO patent assignment data for a specific US patent application number — particularly when you need assignee identity, assignment dates, and official document references without setting up a USPTO API key or account. Ideal for AI agents performing due diligence, IP research, or competitive intelligence that need to pay per query via USDC on Base rather than committing to a subscription.

## Known failure modes

- Invalid or non-existent application number returns empty assignments array
- Malformed application number format may return 400 or empty result
- Application with no recorded assignments returns count:0
- Payment failure via x402/USDC results in 402 Payment Required response
- USPTO data source temporarily unavailable causes service error

## How this service works

Pay-per-call market and economic data API for AI agents: US stocks, ETFs and options, forex, crypto and on-chain perps, energy commodities, US and global macro (Fed, CPI, jobs, GDP, Treasury, World Bank), SEC filings, congressional trades, and market sentiment. No API keys, no accounts. Pay per request in USDC via x402 on Base.

## Output

Returns a JSON object containing the application number, list of assignment records each with assignee details (name and location), assignor names, conveyance type, reel/frame identifier, document download URL, received date, and recorded date, plus a count and USPTO source attribution.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "properties": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "as_of": "2026-06-18T12:00:00.000Z",
  "count": 1,
  "source": "uspto",
  "assignments": [
   {
    "assignees": [
     {
      "name": "ZF PASSIVE SAFETY SYSTEMS US INC.",
      "location": "WASHINGTON, MI, UNITED STATES"
     }
    ],
    "assignors": [
     "BAUCHER, CHRISTOPHER",
     "FISCHER, KURT",
     "MOHANTY, ADITYA"
    ],
    "conveyance": "ASSIGNMENT OF ASSIGNOR'S INTEREST",
    "reel_frame": "068632/0697",
    "document_url": "https://assignmentcenter.uspto.gov/ipas/search/api/v2/public/download/patent/68632/697",
    "received_date": "2024-09-19",
    "recorded_date": "2024-09-19"
   }
  ],
  "attribution": "Source: U.S. Patent and Trademark Office (USPTO) Open Data Portal",
  "application_number": "18687455"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402stock-patent-assignment-lookup-d317862f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402stock.xyz](https://www.zero.xyz/host/x402stock.xyz/llms.txt)