# Crossref API

> Crossref API on Apizie: 3 endpoints (Search works, DOI, Journals) returned as clean JSON through one API key. 3 endpoints are live now. Call it over REST at https://zieapi.vercel.app/v1/research:crossref/{endpoint} or from Claude, ChatGPT and Cursor through the Apizie MCP server. Free plan: 1,000 requests a month.

- Project key: `research:crossref`
- Category: Research
- Status: live
- Source: https://www.crossref.org/documentation/retrieve-metadata/rest-api/
- Page: https://zieapi.vercel.app/api/research/crossref
- OpenAPI: https://zieapi.vercel.app/api/research/crossref/openapi.json

Metadata for 160M+ DOIs: journal articles, books, conference papers and their references.

## Endpoints

### Search works
`GET https://zieapi.vercel.app/v1/research:crossref/works`

| Parameter | Type | Required | Description |
|---|---|---|---|
| query | string | yes |  |
| rows | integer | no | Number of results |
| filter | string | no |  |

### DOI
`GET https://zieapi.vercel.app/v1/research:crossref/doi`

| Parameter | Type | Required | Description |
|---|---|---|---|
| doi | string | yes |  |

### Journals
`GET https://zieapi.vercel.app/v1/research:crossref/journals`

| Parameter | Type | Required | Description |
|---|---|---|---|
| query | string | yes |  |
| rows | integer | no | Number of results |

## Example
```
curl "https://zieapi.vercel.app/v1/research:crossref/works" \
  -H "x-api-key: $APIZIE_KEY"
```

## FAQ

### How do I call the Crossref API?
Create a free Apizie key, then send GET https://zieapi.vercel.app/v1/research:crossref/works with the header x-api-key. Every endpoint returns { project, data, timestamp }.

### Is the Crossref API free on Apizie?
Yes. The Free plan includes 1,000 requests a month at 100 requests a minute, no credit card.

### Can AI agents use the Crossref API?
Yes. Add the Apizie MCP server (https://zieapi.vercel.app/mcp) to Claude, ChatGPT, Cursor or VS Code, then ask in plain language. The agent calls run_scraper with project key research:crossref.

### What is the status of the Crossref API?
Live: works with just an Apizie key