# Scholarly Paper Search via Crossref (150M+ Records)

> Scholarly Paper Search via Crossref (150M+ Records) is a paid API for AI agents from twin.unykorn.org, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-01).

Searches over 150 million scholarly papers indexed in Crossref by keyword query, with optional result limit and year filter.

## Facts

- Endpoint: POST https://twin.unykorn.org/research/paper-search?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-01
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/scholarly-paper-search-via-crossref-150m-records-ee9acab7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_bc_F4b8Ifujt-zdy3F0DI

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 scholarly-paper-search-via-crossref-150m-records-ee9acab7 -d '<json body>'
```

Example prompt: Search Crossref for up to 20 scholarly papers on transformer neural networks published from 2020 onward and show me the titles, authors, and DOIs.

## When to prefer this

Choose this endpoint when you need broad keyword-based discovery across 150M+ scholarly records indexed by Crossref, especially when you don't already have a DOI and want to explore a topic. Prefer it over DOI lookup (which requires an exact DOI) or Google Scholar scraping (which may lack structured metadata). Ideal for literature reviews, research scoping, and academic background research where structured citation metadata is needed.

## Known failure modes

- Empty results if the query is too specific or uses non-standard terminology
- Rate limiting or payment failure if the x402 micropayment is not processed correctly
- Partial results if fewer than the requested limit exist in Crossref for the query
- Malformed request if required 'q' parameter is missing
- from_year filter may exclude relevant older foundational papers

## How this service works

Scholarly paper search across 150M+ Crossref records — Genesis402 / UnyKorn Operator Network

## Output

Returns a list of matching scholarly paper records from Crossref, each typically including title, authors, journal or venue, DOI, publication year, and available abstract or citation metadata, up to the specified limit (default 10, max 40).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "params": {
   "type": "object",
   "properties": {
    "q": {
     "type": "string",
     "description": "required"
    },
    "limit": {
     "type": "integer",
     "maximum": 40,
     "minimum": 1,
     "description": "optional: max rows (default 10, max 40)"
    },
    "from_year": {
     "type": "integer",
     "maximum": 2100,
     "minimum": 1800,
     "description": "optional"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/scholarly-paper-search-via-crossref-150m-records-ee9acab7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from twin.unykorn.org](https://www.zero.xyz/host/twin.unykorn.org/llms.txt)