# Reference Verifier – DOI & Citation Checker (`researchdata/crossref-reference-verifier`) Actor

Check DOIs and full citations: does each reference exist, canonical metadata, match confidence, plus retraction, correction and expression-of-concern flags (Crossref + Retraction Watch). For grant proposals, manuscripts and AI-written text.

- **URL**: https://apify.com/researchdata/crossref-reference-verifier.md
- **Developed by:** [Research Analyst](https://apify.com/researchdata) (community)
- **Stats:** 2 total users, 1 monthly users, 100.0% runs succeeded, 0 bookmarks
- **User rating**: No ratings yet

## Pricing

from $10.00 / 1,000 reference checkeds

This Actor is paid per event. You are not charged for the Apify platform usage, but only a fixed price for specific events.

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

## Reference Verifier – DOI & Citation Checker

Paste DOIs or full citations; get back whether each reference really exists, its canonical metadata, a match confidence for free-text citations, and flags for retractions, corrections and expressions of concern.

### Why use it

- Check reference lists of grant proposals and manuscripts before submission
- Catch hallucinated references in AI-written text
- Screen bibliographies for retracted papers

No API keys, no scraping of HTML – the actor talks to the official public API, handles paging,
rate limits and retries, and returns flat JSON you can export as CSV/Excel or call from code,
Make, Zapier, n8n or AI agents (Apify MCP server).

### Input

| Field | Title | Description |
|---|---|---|
| `references` | References | One DOI or one full citation per line. |
| `checkRetractions` | Check retractions & corrections | Look up update notices (Crossref, incl. Retraction Watch data). |
| `email` | Contact e-mail | Optional; routes requests to Crossref's faster 'polite' pool. |

Example input:

```json
{
  "references": [
    "10.1038/nature14539",
    "Jumper J et al. Highly accurate protein structure prediction with AlphaFold. Nature 2021"
  ],
  "checkRetractions": true
}
```

### Output (one dataset item per result)

```json
{
  "input": "10.1038/nature14539",
  "inputType": "doi",
  "status": "verified",
  "title": "Deep learning",
  "authors": [
    "Yann LeCun",
    "Yoshua Bengio",
    "Geoffrey Hinton"
  ],
  "journal": "Nature",
  "year": 2015,
  "matchConfidence": 1.0,
  "updateNotices": [],
  "retractedOrConcern": false,
  "url": "https://doi.org/10.1038/nature14539"
}
```

#### Status values

`verified` (DOI resolves) · `verified_arxiv` (arXiv ID exists and matches the title) · `partial_match` (similar paper found, check details) · `arxiv_id_not_found` · `arxiv_id_title_mismatch` · `doi_title_mismatch` (DOI exists but belongs to a different paper than the cited title – typical for invented references) · `doi_not_found` · `probable_match` (citation matched with ≥85 % title coverage and consistent year) · `no_reliable_match` · `error`

### Pricing

Pay per event: **$0.01 per `reference-checked`** (reference checked). You only pay for results you get;
set a max cost per run to cap spending.

### Data source & terms

Crossref REST API (metadata CC0; Retraction Watch data via Crossref). Please respect the data provider's terms and cite the original resource in publications.
This actor is an independent tool and is not affiliated with or endorsed by the data provider.

# Actor input Schema

## `references` (type: `array`):

One DOI or one full citation per line.

## `checkRetractions` (type: `boolean`):

Look up update notices (Crossref, incl. Retraction Watch data).

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

Optional; routes requests to Crossref's faster 'polite' pool.

## Actor input object example

```json
{
  "references": [
    "10.1038/nature14539",
    "Jumper J et al. Highly accurate protein structure prediction with AlphaFold. Nature 2021"
  ],
  "checkRetractions": true
}
```

# Actor output Schema

## `results` (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 = {
    "references": [
        "10.1038/nature14539",
        "Jumper J et al. Highly accurate protein structure prediction with AlphaFold. Nature 2021"
    ]
};

// Run the Actor and wait for it to finish
const run = await client.actor("researchdata/crossref-reference-verifier").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 = { "references": [
        "10.1038/nature14539",
        "Jumper J et al. Highly accurate protein structure prediction with AlphaFold. Nature 2021",
    ] }

# Run the Actor and wait for it to finish
run = client.actor("researchdata/crossref-reference-verifier").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 '{
  "references": [
    "10.1038/nature14539",
    "Jumper J et al. Highly accurate protein structure prediction with AlphaFold. Nature 2021"
  ]
}' |
apify call researchdata/crossref-reference-verifier --silent --output-dataset

```

## MCP server setup

```json
{
    "mcpServers": {
        "apify": {
            "type": "http",
            "url": "https://mcp.apify.com/?tools=fetch-actor-details,researchdata/crossref-reference-verifier"
        }
    }
}
```

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/Kst9zYI8joqAbopde/builds/qPhCcg03QkvV09QZz/openapi.json