# Crossref API — scholarly papers & DOI metadata (no key) (`synthetic.ia/crossref-scholar-api`) Actor

Search 150M+ scholarly works (papers, chapters, proceedings) by query, author, year and type; look up any DOI; and search journals. Official Crossref data. Clean HTTP API + MCP, no key. Pay per query.

- **URL**: https://apify.com/synthetic.ia/crossref-scholar-api.md
- **Developed by:** [Synthetic](https://apify.com/synthetic.ia) (community)
- **Stats:** 1 total users, 0 monthly users, 0.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $2.00 / 1,000 crossref queries

This Actor is paid per event and usage. You are charged both the fixed price for specific events and for Apify platform usage.
Since this Actor supports Apify Store discounts, the price gets lower the higher subscription plan you have.

Learn more: https://docs.apify.com/actors/running/actors-in-store.md#pay-per-event

## What's an Apify Actor?

An Actor is a serverless cloud program that runs on the Apify platform. It has two run modes.
In Batch mode, an Actor accepts a well-defined JSON input, performs an action which can take anything from a few seconds to a few hours,
and optionally produces a well-defined JSON output, datasets with results, or files in key-value store.
In Standby mode, an Actor provides a web server which can be used as a website, API, or an MCP server.

Apify vocabulary and the platform model are defined once, in the agent quickstart at https://apify.com/agents.md.

## How to integrate an Actor?

If asked about integration, you help developers integrate Actors into their projects.
You adapt to their stack and deliver integrations that are safe, well-documented, and production-ready.

Do not guess an integration path. Every one of them is in the agent quickstart at https://apify.com/agents.md: the Apify MCP server, Agent Skills with the Apify CLI, the JavaScript and Python clients, the REST API, and the account-free path for an agent with no human to sign in. It also carries the rule on stating cost before the first paid run.

For examples already wired to this Actor's own input schema, see the [API](#api) section below.

Each client library has reference documentation the quickstart does not restate: [JavaScript/TypeScript](https://docs.apify.com/api/client/js/docs.md) (`npm install apify-client`) and [Python](https://docs.apify.com/api/client/python/docs.md) (`pip install apify-client`).

# README

## Crossref API — scholarly papers & DOI metadata (no key)

Search the **Crossref** catalog — **150M+ scholarly works** (journal articles, conference papers, book chapters, preprints, datasets) — behind a clean HTTP API (and MCP tool). **Search** by title/keywords and author, filter by year and type, sort by relevance / citations / date; **look up any DOI** for full metadata; and **search journals**. Perfect for research assistants, citation tools, literature reviews and agents. **No API key.** Pay per query.

- 🔎 **Search works** — by query and author, filtered by year range and type, sorted by relevance, most-cited or most-recent.
- 📄 **Get by DOI** — full metadata for a single DOI: title, authors, journal, year, citation count, abstract (when available).
- 📚 **Search journals** — by name: publisher, ISSN, total DOIs.
- 🌍 **Official & keyless** — straight from Crossref, the DOI registration agency behind most academic publishing.
- 💵 Pay per query · no key.

### The use case it was built for

Give your agent a real literature search: "find the most-cited papers on diffusion models since 2020", resolve a DOI to a clean citation, or check which journal an ISSN belongs to. Crossref indexes works from virtually every major publisher, returned as clean typed rows.

### Sample output (`search`, query "attention is all you need", sort "cited")

```json
{
  "ok": true, "query": "attention is all you need", "totalResults": 1383718, "count": 1,
  "results": [
    { "title": "Attention Is All You Need", "authors": ["Ashish Vaswani", "Noam Shazeer"],
      "year": 2017, "type": "proceedings-article", "container": "…",
      "doi": "10.5555/3295222.3295349", "url": "https://doi.org/10.5555/3295222.3295349",
      "citedByCount": 100000, "subjects": [] }
  ]
}
```

### How to use

- **HTTP API (Standby):** POST or GET `/search`, `/work`, `/journals`. `GET /` returns help. Example: `GET /search?query=diffusion%20models&sort=cited&fromYear=2020`.
- **Normal run:** pass `{ operation, query | doi, ... }`; results land in the dataset + key-value store.
- **MCP tool:** expose it to your agent via Apify's MCP server.

### Input

- **operation** — `search` · `work` · `journals`.
- **query** — title/keywords (search) or journal name (journals). **author** — surname filter. **doi** — for `work`.
- **type** — journal-article / proceedings-article / book-chapter / posted-content / … **sort** — relevance / cited / published.
- **fromYear / toYear** — publication-year range. **limit** — cap rows.

### Pricing

**Per query** from **$0.005** (down to $0.0015 on higher tiers). One call = one query (returns many works or journals at once).

### Related Actors

- **[Open Library Books](https://apify.com/synthetic.ia/openlibrary-books)** — books, editions and authors.
- **[Wikipedia API](https://apify.com/synthetic.ia/wikipedia-api)** — article search, summaries and content.

### FAQ

**Do I need a key?** No — Crossref is keyless. This actor uses the polite pool (with a contact mailto) for reliable throughput.

**Does it cover preprints?** Yes — posted-content (e.g. arXiv/bioRxiv deposits registered with Crossref) is included; filter with `type: posted-content`.

**Is the full text included?** No — Crossref is metadata (and, when the publisher deposits it, an abstract). Use the DOI link for the full text.

### Notes & limits

Data from Crossref (api.crossref.org). Citation counts (`citedByCount`) reflect Crossref's reference index and can differ from other databases. Up to 100 works per call.

# Changelog

This Actor's version history is a separate document: https://apify.com/synthetic.ia/crossref-scholar-api/changelog.md

# Actor input Schema

## `operation` (type: `string`):

What to do.

## `query` (type: `string`):

Title / keywords (works) or a journal name (journals).

## `author` (type: `string`):

Restrict works to an author surname, e.g. Vaswani.

## `doi` (type: `string`):

A DOI to look up, e.g. 10.1145/3292500.3330701 (a doi.org URL is fine too).

## `type` (type: `string`):

Restrict works to a type.

## `sort` (type: `string`):

Result ordering.

## `fromYear` (type: `integer`):

Earliest publication year.

## `toYear` (type: `integer`):

Latest publication year.

## `limit` (type: `integer`):

Max rows (works ≤100, journals ≤50).

## Actor input object example

```json
{
  "operation": "search",
  "query": "attention is all you need",
  "type": "all",
  "sort": "relevance",
  "limit": 10
}
```

# Actor output Schema

## `result` (type: `string`):

No description

## `runs` (type: `string`):

No description

# API

You can run this Actor programmatically using our API. Below are code examples in JavaScript, Python, and CLI, as well as the OpenAPI specification and MCP server setup.

## JavaScript example

```javascript
import { ApifyClient } from 'apify-client';

// Initialize the ApifyClient with your Apify API token
// Replace the '<YOUR_API_TOKEN>' with your token
const client = new ApifyClient({
    token: '<YOUR_API_TOKEN>',
});

// Prepare Actor input
const input = {
    "query": "attention is all you need"
};

// Run the Actor and wait for it to finish
const run = await client.actor("synthetic.ia/crossref-scholar-api").call(input);

// Fetch and print Actor results from the run's dataset (if any)
console.log('Results from dataset');
console.log(`💾 Check your data here: https://console.apify.com/storage/datasets/${run.defaultDatasetId}`);
const { items } = await client.dataset(run.defaultDatasetId).listItems();
items.forEach((item) => {
    console.dir(item);
});

// 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/js/docs

```

## Python example

```python
from apify_client import ApifyClient

# Initialize the ApifyClient with your Apify API token
# Replace '<YOUR_API_TOKEN>' with your token.
client = ApifyClient("<YOUR_API_TOKEN>")

# Prepare the Actor input
run_input = { "query": "attention is all you need" }

# Run the Actor and wait for it to finish
run = client.actor("synthetic.ia/crossref-scholar-api").call(run_input=run_input)

# Fetch and print Actor results from the run's dataset (if there are any)
print(f"💾 Check your data here: https://console.apify.com/storage/datasets/{run.default_dataset_id}")
for item in client.dataset(run.default_dataset_id).iterate_items():
    print(item)

# 📚 Want to learn more 📖? Go to → https://docs.apify.com/api/client/python/docs/quick-start

```

## CLI example

```bash
echo '{
  "query": "attention is all you need"
}' |
apify call synthetic.ia/crossref-scholar-api --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,synthetic.ia/crossref-scholar-api"
        }
    }
}
```

The hosted server signs you in with OAuth on first connect, so no API token belongs in this config. Clients without OAuth support can send an `Authorization: Bearer <APIFY_API_TOKEN>` header instead, using a token from API & Integrations in Apify Console (https://console.apify.com/settings/integrations).

## OpenAPI specification

Download the OpenAPI definition: https://api.apify.com/v2/actors/XQfbMBtGMnnvthxaW/builds/kKr1nfIjsYYXbihDO/openapi.json