# Crossref API

> Crossref returns formatted citations and publication details as a workflow and API.

Get citation returns citation and publication details for a title or DOI; optional author and year help match the work.

- Page: https://fous.com/workflows/crossref
- Handle: `@crossref`
- Category: [Science](https://fous.com/workflows/category/science)
- Source website: https://crossref.org
- Last verified: Sep 29, 2026
- Fous is not affiliated with Crossref.

## Methods

### Get citation

Operation `get_citation`, version 1. 1 credit per call.

Get a formatted citation and publication details for the best-matching Crossref work by title or DOI. Optional author and year help choose among similar works; citations reflect the metadata deposited with Crossref.

**Input**

| Field | Type | Required | Example | Description |
|---|---|---|---|---|
| `work` | string | yes | `"The Structure of Scientific Revolutions"` | Paper or book title or DOI, for example The Structure of Scientific Revolutions or 10.1038/nrd842. |
| `year` | integer | no | `1996` | Publication year to help select a work, for example 1996. |
| `style` | string | no | `"apa"` | Citation style, for example mla. |
| `author` | string | no | `"Thomas S. Kuhn"` | Author to help select a work, for example Thomas S. Kuhn. |

**Input schema**

```json
{
  "type": "object",
  "required": [
    "work"
  ],
  "properties": {
    "work": {
      "type": "string",
      "description": "Paper or book title or DOI, for example The Structure of Scientific Revolutions or 10.1038/nrd842.",
      "examples": [
        "The Structure of Scientific Revolutions",
        "10.1038/nrd842"
      ]
    },
    "year": {
      "type": "integer",
      "description": "Publication year to help select a work, for example 1996.",
      "examples": [
        1996,
        2012
      ]
    },
    "style": {
      "enum": [
        "apa",
        "mla",
        "chicago",
        "harvard",
        "ieee",
        "vancouver"
      ],
      "type": "string",
      "default": "apa",
      "description": "Citation style, for example mla.",
      "examples": [
        "apa",
        "mla",
        "chicago"
      ]
    },
    "author": {
      "type": "string",
      "default": "",
      "description": "Author to help select a work, for example Thomas S. Kuhn.",
      "examples": [
        "Thomas S. Kuhn"
      ]
    }
  },
  "additionalProperties": false,
  "examples": [
    {
      "work": "The Structure of Scientific Revolutions",
      "year": 1996,
      "style": "apa",
      "author": "Thomas S. Kuhn"
    },
    {
      "work": "10.1038/nrd842",
      "style": "mla"
    },
    {
      "work": "The Structure of Scientific Revolutions",
      "year": 2012,
      "style": "chicago",
      "author": "Thomas S. Kuhn"
    }
  ]
}
```

**Output**

| Field | Type | Example | Description |
|---|---|---|---|
| `doi` | string | `"10.7208/chicago/9780226458106.001.0001"` |  |
| `type` | string or null | `"book"` |  |
| `year` | integer or null | `1996` |  |
| `issue` | string or null | `"7"` |  |
| `pages` | string or null | `"491-492"` |  |
| `title` | string or null | `"The Structure of Scientific Revolutions"` |  |
| `volume` | string or null | `"1"` |  |
| `authors` | array |  |  |
| `citation` | string | `"Kuhn, T. S. (1996). The Structure of Scientific Revolutions. University of Chicago Press. https://doi.org/10.7208/chica` |  |
| `doi_link` | string | `"https://doi.org/10.7208/chicago/9780226458106.001.0001"` |  |
| `journal_or_publisher` | string or null | `"University of Chicago Press"` |  |

**Example input**

```json
{
  "work": "The Structure of Scientific Revolutions",
  "year": 1996,
  "style": "apa",
  "author": "Thomas S. Kuhn"
}
```

**Example output**

```json
{
  "doi": "10.7208/chicago/9780226458106.001.0001",
  "type": "book",
  "year": 1996,
  "issue": null,
  "pages": null,
  "title": "The Structure of Scientific Revolutions",
  "volume": null,
  "authors": [
    "Thomas S. Kuhn"
  ],
  "citation": "Kuhn, T. S. (1996). The Structure of Scientific Revolutions. University of Chicago Press. https://doi.org/10.7208/chicago/9780226458106.001.0001",
  "doi_link": "https://doi.org/10.7208/chicago/9780226458106.001.0001",
  "journal_or_publisher": "University of Chicago Press"
}
```

## Quick start

Call the API with a Fous API key (`FOUS_API_KEY`). To create one, turn on Developer mode in Fous Studio, then open Keys & connections → API keys (https://app.fous.com/keys).

```bash
# First set your key: export FOUS_API_KEY='YOUR_FOUS_API_KEY'
: "${FOUS_API_KEY:?Set FOUS_API_KEY before running this example}"

curl 'https://api.fous.com/v1/query' \
  --fail-with-body --silent --show-error --max-time 120 \
  -H "Authorization: Bearer $FOUS_API_KEY" \
  -H 'Content-Type: application/json' \
  --data-raw '{
  "api": "@crossref",
  "visibility": "public",
  "operation": "get_citation",
  "version": 1,
  "input": {
    "work": "The Structure of Scientific Revolutions",
    "year": 1996,
    "style": "apa",
    "author": "Thomas S. Kuhn"
  },
  "response": {
    "format": "json"
  }
}'
```

```python
# Save as fous.py and run with python3 fous.py. No packages needed.
# First set your key: export FOUS_API_KEY='YOUR_FOUS_API_KEY'
import json
import os
import urllib.error
import urllib.request

api_key = os.environ.get("FOUS_API_KEY")
if not api_key:
    raise RuntimeError("Set FOUS_API_KEY before running this example")

body = json.loads("{\n  \"api\": \"@crossref\",\n  \"visibility\": \"public\",\n  \"operation\": \"get_citation\",\n  \"version\": 1,\n  \"input\": {\n    \"work\": \"The Structure of Scientific Revolutions\",\n    \"year\": 1996,\n    \"style\": \"apa\",\n    \"author\": \"Thomas S. Kuhn\"\n  },\n  \"response\": {\n    \"format\": \"json\"\n  }\n}")
request = urllib.request.Request(
    "https://api.fous.com/v1/query",
    data=json.dumps(body).encode("utf-8"),
    headers={
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    },
    method="POST",
)
try:
    with urllib.request.urlopen(request, timeout=120) as response:
        result = json.load(response)
except urllib.error.HTTPError as error:
    raise RuntimeError(f"HTTP {error.code}: {error.read().decode('utf-8', errors='replace')}") from error
if result.get("success") is False:
    raise RuntimeError(result.get("error", {}).get("message", "Request failed"))
print(json.dumps(result["data"]["output"], indent=2))
```

```typescript
// Save as fous.mts and run with npx tsx fous.mts.
// First set your key: export FOUS_API_KEY='YOUR_FOUS_API_KEY'
const apiKey = process.env.FOUS_API_KEY;
if (!apiKey) throw new Error("Set FOUS_API_KEY before running this example");

const response = await fetch("https://api.fous.com/v1/query", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  signal: AbortSignal.timeout(120_000),
  body: JSON.stringify({
  "api": "@crossref",
  "visibility": "public",
  "operation": "get_citation",
  "version": 1,
  "input": {
    "work": "The Structure of Scientific Revolutions",
    "year": 1996,
    "style": "apa",
    "author": "Thomas S. Kuhn"
  },
  "response": {
    "format": "json"
  }
}),
});
type ApiResult = { success: boolean; data?: { output: unknown }; error?: { message: string } };
const result: ApiResult = await response.json();
if (!response.ok || result.success === false) {
  throw new Error(result.error?.message ?? `HTTP ${response.status}`);
}
if (!result.data) throw new Error("Missing API response data");
console.log(result.data.output);
```

Or describe the data in plain language: send `{"api":"@crossref","prompt":"Describe the data you need, with every detail"}` to the same URL. Fous fills in the input, runs the method that fits and returns only the fields you asked for; `data.route.calls[].request` is the exact call it made. Routing is free; the run costs the same.

## Use cases

- Create formatted citations for papers and books
- Look up publication details from a DOI
- Match a work using its title, author, and year
- Format citations in a chosen style

## FAQ

### Is Fous affiliated with Crossref?

No. Fous is not affiliated with Crossref. This workflow reads the public crossref.org website and returns its data.

### How much does it cost?

Each run costs 1 credit. With pay-as-you-go, a credit costs 1¢; monthly plans cost less per credit.

### Do I need a Crossref account?

No. You only need a Fous account.

### How current is the data?

Fous gets the data from crossref.org when you run it; repeating the same request within a day may return the saved result. Fous checks this workflow automatically; it last passed a check on Sep 29, 2026.

### How can I get a citation for a paper title?

Use Get citation with the paper title; add an author or year to help match the work.

### What publication details are available for a DOI?

Get citation accepts a DOI and returns details such as the title, authors, year, journal or publisher, and pages.

### Can I choose a citation style?

Yes. Get citation accepts a style, such as mla, to format the citation.

## Related

- [Google Scholar API](https://fous.com/workflows/google-scholar.md): Google Scholar provides papers, citing papers, ready-made citations and researcher profiles with metrics and up to 20 top-cited papers; public access may be temporarily limited.
- [Semantic Scholar API](https://fous.com/workflows/semantic-scholar.md): Semantic Scholar returns paper and citation search, paper abstracts, summaries, authors and influence, plus author metrics and up to 10 top-cited papers; dates, summaries, PDFs and affiliation matches may be unavailable.
- [ORCID API](https://fous.com/workflows/orcid.md): Researcher identifiers and public research records.
- [PubMed API](https://fous.com/workflows/pubmed.md): PubMed searches medical and life-science articles by topic and retrieves one article’s abstract and publication details; abstracts and free full-text links may be unavailable.
- [Unpaywall API](https://fous.com/workflows/unpaywall.md): Find free-to-read scholarly papers and their legal copies.
- [arXiv API](https://fous.com/workflows/arxiv.md): arXiv returns up to 100 matching research preprints or individual paper details, and newly announced subject papers in announcement order; announcement dates may differ from today, and replacements are excluded.
- [OpenAlex API](https://fous.com/workflows/openalex.md): OpenAlex is an open catalog of scholarly research and connections, offering ranked papers and institution research summaries with annual output, leading topics, and coauthors.
- [Metacritic API](https://fous.com/workflows/metacritic.md): Metacritic provides critic and user scores for games, movies, TV shows, and albums, plus reviews and title details; some albums may match another release, and rankings may omit user scores or dates.
- [All Science workflows](https://fous.com/workflows/category/science)