Content Access

Open access tools for academic papers

Unpaywall browser extension

Unpaywall finds free, legal copies of 20+ million academic papers.

# Unpaywall API (free, requires email for identification)
import requests

def find_open_access(doi: str, email: str) -> dict:
    """Find open access version of a paper using Unpaywall API.

    Args:
        doi: Digital Object Identifier (e.g., "10.1038/nature12373")
        email: Your email for API identification

    Returns:
        Dict with best open access URL if available
    """
    url = f"https://api.unpaywall.org/v2/{doi}?email={email}"

    response = requests.get(url, timeout=30)

    if response.status_code != 200:
        return {'error': f'Status {response.status_code}'}

    data = response.json()

    if data.get('is_oa'):
        best_location = data.get('best_oa_location', {})
        return {
            'is_open_access': True,
            'oa_url': best_location.get('url_for_pdf') or best_location.get('url'),
            'oa_status': data.get('oa_status'),  # gold, green, bronze, hybrid
            'host_type': best_location.get('host_type'),  # publisher, repository
            'version': best_location.get('version')  # publishedVersion, acceptedVersion
        }

    return {
        'is_open_access': False,
        'title': data.get('title'),
        'journal': data.get('journal_name')
    }

# Usage
result = find_open_access("10.1038/nature12373", "[email protected]")
if result.get('is_open_access'):
    print(f"Free PDF at: {result['oa_url']}")

CORE API (295M papers)

# CORE API - requires free API key from https://core.ac.uk/

import requests

class CORESearch:
    def __init__(self, api_key: str):
        self.api_key = api_key
        self.base_url = "https://api.core.ac.uk/v3"

    def search(self, query: str, limit: int = 10) -> list:
        """Search CORE database for open access papers."""

        headers = {'Authorization': f'Bearer {self.api_key}'}
        params = {
            'q': query,
            'limit': limit
        }

        response = requests.get(
            f"{self.base_url}/search/works",
            headers=headers,
            params=params,
            timeout=30
        )

        if response.status_code != 200:
            return []

        data = response.json()
        results = []

        for item in data.get('results', []):
            results.append({
                'title': item.get('title'),
                'authors': [a.get('name') for a in item.get('authors', [])],
                'year': item.get('yearPublished'),
                'doi': item.get('doi'),
                'download_url': item.get('downloadUrl'),
                'abstract': item.get('abstract', '')[:500]
            })

        return results

    def get_by_doi(self, doi: str) -> dict:
        """Get paper by DOI."""
        headers = {'Authorization': f'Bearer {self.api_key}'}

        response = requests.get(
            f"{self.base_url}/works/{doi}",
            headers=headers,
            timeout=30
        )

        return response.json() if response.status_code == 200 else {}

Semantic Scholar API (214M papers)

# Semantic Scholar API - free, no key required for basic use

import requests

def search_semantic_scholar(query: str, limit: int = 10) -> list:
    """Search Semantic Scholar for papers with open access links."""

    url = "https://api.semanticscholar.org/graph/v1/paper/search"
    params = {
        'query': query,
        'limit': limit,
        'fields': 'title,authors,year,abstract,openAccessPdf,citationCount'
    }

    response = requests.get(url, params=params, timeout=30)

    if response.status_code != 200:
        return []

    results = []
    for paper in response.json().get('data', []):
        oa_pdf = paper.get('openAccessPdf', {})
        results.append({
            'title': paper.get('title'),
            'authors': [a.get('name') for a in paper.get('authors', [])],
            'year': paper.get('year'),
            'citations': paper.get('citationCount', 0),
            'open_access_url': oa_pdf.get('url') if oa_pdf else None,
            'abstract': paper.get('abstract', '')[:500] if paper.get('abstract') else ''
        })

    return results

def get_paper_by_doi(doi: str) -> dict:
    """Get paper details by DOI."""
    url = f"https://api.semanticscholar.org/graph/v1/paper/DOI:{doi}"
    params = {
        'fields': 'title,authors,year,abstract,openAccessPdf,references,citations'
    }

    response = requests.get(url, params=params, timeout=30)
    return response.json() if response.status_code == 200 else {}

Library database access

Checking library access programmatically

# Most library databases require authentication
# This shows how to structure library API access

class LibraryAccess:
    """Access pattern for library databases."""

    # Common library database endpoints
    DATABASES = {
        'pressreader': {
            'base': 'https://www.pressreader.com',
            'auth': 'library_card',
            'content': '7000+ newspapers/magazines'
        },
        'proquest': {
            'base': 'https://www.proquest.com',
            'auth': 'institutional',
            'content': 'news, dissertations, documents'
        },
        'jstor': {
            'base': 'https://www.jstor.org',
            'auth': 'institutional',
            'content': 'academic journals, books'
        },
        'nexis_uni': {
            'base': 'https://www.nexisuni.com',
            'auth': 'institutional',
            'content': 'legal, news, business'
        }
    }

# Interlibrary Loan (ILL) workflow
def request_via_ill(paper_info: dict, library_email: str) -> str:
    """Generate interlibrary loan request.

    ILL is free through most libraries and can get almost any paper.
    Turnaround: typically 3-7 days.
    """

    request = f"""
    INTERLIBRARY LOAN REQUEST

    Title: {paper_info.get('title')}
    Author(s): {paper_info.get('authors')}
    Journal: {paper_info.get('journal')}
    Year: {paper_info.get('year')}
    DOI: {paper_info.get('doi')}
    Volume/Issue: {paper_info.get('volume')}/{paper_info.get('issue')}
    Pages: {paper_info.get('pages')}

    Requested by: {library_email}
    """

    return request.strip()

Direct author contact

Email template for paper requests

def generate_paper_request_email(paper: dict, requester: dict) -> str:
    """Generate professional email requesting paper from author.

    Authors are typically happy to share their work.
    Success rate: Very high (70-90%).
    """

    template = f"""
Subject: Request for paper: {paper['title'][:50]}...

Dear Dr./Prof. {paper['author_last_name']},

I am a {requester['role']} at {requester['institution']}, researching
{requester['research_area']}.

I came across your paper "{paper['title']}" published in
{paper['journal']} ({paper['year']}), and I believe it would be
highly relevant to my work on {requester['specific_project']}.

Unfortunately, I don't have access through my institution. Would you
be willing to share a copy?

I would be happy to properly cite your work in any resulting publications.

Thank you for your time and for your contribution to the field.

Best regards,
{requester['name']}
{requester['title']}
{requester['institution']}
{requester['email']}
"""

    return template.strip()

Wayback Machine for historical access

def get_wayback_article(url: str) -> str:
    """Get article from Wayback Machine.

    100% legal - the Internet Archive is a recognized library.
    May have older versions of articles (before paywall implemented).
    """

    # Check availability
    api_url = f"http://archive.org/wayback/available?url={url}"

    try:
        response = requests.get(api_url, timeout=10)
        data = response.json()

        snapshot = data.get('archived_snapshots', {}).get('closest', {})

        if snapshot.get('available'):
            return snapshot['url']

        return None
    except Exception:
        return None

Access strategy by content type

Academic papers

## Academic paper access strategies (in order)

1. **Unpaywall extension** - Check first, automatic
2. **Google Scholar** - Click "All versions", look for [PDF]
3. **Author's website** - Check their academic page
4. **Institutional repository** - Search university library
5. **Preprint servers** - arXiv, SSRN, bioRxiv, medRxiv
6. **ResearchGate/Academia.edu** - Author-uploaded copies
7. **CORE.ac.uk** - 295M open access papers
8. **PubMed Central** - For biomedical papers
9. **Contact author directly** - High success rate
10. **Interlibrary Loan** - Free, gets almost anything

Books and reports

## Book/report access strategies

1. **Library digital lending** - Internet Archive, OverDrive
2. **Google Books** - Often has preview or full text
3. **HathiTrust** - Academic library consortium
4. **Project Gutenberg** - Public domain books
5. **OpenLibrary** - Internet Archive's book lending
6. **Publisher open access** - Some chapters/reports free
7. **Author/organization website** - Reports often available
8. **Interlibrary Loan** - Physical books, scanned chapters

Legal and ethical framework

Best practices for researchers

## Ethical content access guidelines

### DO:
- Use library resources first (supports the ecosystem)
- Try open access tools before circumvention
- Contact authors directly (they want citations)
- Cite properly regardless of how you accessed content
- Budget for subscriptions to frequently-used sources

### DON'T:
- Share login credentials
- Systematically download entire databases
- Use bypassed content for commercial purposes
- Redistribute paywalled content
- Rely solely on bypass methods