Base academic search

BASE (Bielefeld Academic Search Engine) API

Overview

BASE is one of the world's largest search engines for academic open access web resources. Operated by Bielefeld University Library, it indexes 400M+ documents from 11,000+ content providers including institutional repositories, preprint servers, and digital libraries. Unlike Google Scholar, BASE provides structured metadata, license information, and full-text links. The API is free with registration.

API Endpoints

Base URL

https://api.base-search.net/cgi-bin/BaseHttpSearchInterface.fcgi

Search

# Basic keyword search (JSON response)
curl "https://api.base-search.net/cgi-bin/BaseHttpSearchInterface.fcgi?\
func=PerformSearch&query=climate+change+adaptation&format=json&hits=20"

# Search with field filters
curl "https://api.base-search.net/cgi-bin/BaseHttpSearchInterface.fcgi?\
func=PerformSearch&query=dctitle:transformer+AND+dcsubject:NLP&format=json"

# Filter by document type and year
curl "https://api.base-search.net/cgi-bin/BaseHttpSearchInterface.fcgi?\
func=PerformSearch&query=deep+learning&dctypenorm=121&dcyear:2024&format=json"

# Open access only
curl "https://api.base-search.net/cgi-bin/BaseHttpSearchInterface.fcgi?\
func=PerformSearch&query=CRISPR&dcrights:open&format=json"

Search Fields

Field	Description	Example
dctitle	Title	dctitle:attention+mechanism
dccreator	Author	dccreator:vaswani
dcsubject	Subject/keywords	dcsubject:machine+learning
dcdescription	Abstract	dcdescription:neural+network
dcyear	Publication year	dcyear:2024
dctype	Document type text	dctype:article
dctypenorm	Normalized type code	121 (journal article)
dcrights	Access rights	dcrights:open
dclang	Language	dclang:eng
dclink	Source URL	dclink:arxiv.org
dcoa	Open access status	dcoa:1 (OA), dcoa:2 (restricted)
dcprovider	Content provider	dcprovider:arxiv.org

Document Type Codes

Code	Type
121	Journal article
122	Book / monograph
14	Conference paper
15	Thesis / dissertation
17	Report
18	Preprint

Query Parameters

Parameter	Description	Default
func	Must be PerformSearch	Required
query	Search query with optional field prefixes	Required
format	Response format: json or xml	xml
hits	Results per page (max 125)	10
offset	Pagination offset	0
sortby	Sort: dcyear desc, score desc	relevance

Response Structure

{
  "response": {
    "numFound": 45200,
    "start": 0,
    "docs": [
      {
        "dctitle": "Attention Is All You Need",
        "dccreator": ["Ashish Vaswani", "Noam Shazeer"],
        "dcyear": "2017",
        "dcsubject": ["machine learning", "attention mechanism"],
        "dcdescription": "The dominant sequence transduction models...",
        "dcidentifier": "https://arxiv.org/abs/1706.03762",
        "dcsource": "arXiv.org",
        "dcprovider": "arxiv.org",
        "dcdocid": "abc123xyz",
        "dcoa": 1,
        "dctypenorm": ["18"],
        "dclang": ["eng"]
      }
    ]
  }
}

Python Usage

import requests

BASE_URL = "https://api.base-search.net/cgi-bin/BaseHttpSearchInterface.fcgi"


def search_base(query: str, hits: int = 20,
                doc_type: int = None, oa_only: bool = False) -> list:
    """Search BASE for academic open access documents."""
    q = query
    if doc_type:
        q += f" AND dctypenorm:{doc_type}"
    if oa_only:
        q += " AND dcoa:1"

    params = {
        "func": "PerformSearch",
        "query": q,
        "format": "json",
        "hits": hits,
        "sortby": "dcyear desc",
    }

    resp = requests.get(BASE_URL, params=params)
    resp.raise_for_status()
    data = resp.json()

    results = []
    for doc in data.get("response", {}).get("docs", []):
        results.append({
            "title": doc.get("dctitle"),
            "authors": doc.get("dccreator", []),
            "year": doc.get("dcyear"),
            "source": doc.get("dcsource"),
            "url": doc.get("dcidentifier"),
            "abstract": (doc.get("dcdescription") or "")[:300],
            "open_access": doc.get("dcoa") == 1,
            "type": doc.get("dctypenorm", []),
        })
    return results


def search_dissertations(topic: str, lang: str = "eng") -> list:
    """Find dissertations and theses on a topic."""
    query = f"{topic} AND dctypenorm:15 AND dclang:{lang}"
    return search_base(query, hits=50)


def search_by_provider(query: str, provider: str) -> list:
    """Search within a specific content provider."""
    full_query = f"{query} AND dcprovider:{provider}"
    return search_base(full_query)


# Example: find recent open access ML papers
papers = search_base("transformer self-attention", hits=10, oa_only=True)
for p in papers:
    oa = "OA" if p["open_access"] else "restricted"
    print(f"[{p['year']}] {p['title']} ({oa}) — {p['source']}")

# Example: find dissertations on climate modeling
theses = search_dissertations("climate modeling ocean")
for t in theses:
    print(f"[{t['year']}] {t['title']} — {', '.join(t['authors'][:2])}")

BASE vs Other Search Engines

Feature	BASE	Google Scholar	OpenAlex
Records	400M+	Unknown	250M+
Open access focus	Yes	No	Yes
Structured API	Yes	No official API	Yes
License metadata	Yes	No	Partial
Dissertation coverage	Excellent	Good	Limited
Repository-level filtering	Yes	No	No

References

• BASE Search Engine
• BASE API Documentation
• BASE Content Providers