Crossref Local
FreeNot checkedA local CrossRef database MCP server enabling full-text search across 167M+ scholarly works, citation analysis, and impact factor retrieval without rate limits
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A local CrossRef database MCP server enabling full-text search across 167M+ scholarly works, citation analysis, and impact factor retrieval without rate limits or internet dependency.
README
CrossRef Local (crossref-local)
Local CrossRef database with 167M+ scholarly works, full-text search, and impact factor calculation
Demo
# Search 167M papers locally — no API rate limits, ~22 ms full-text query
crossref-local search "epilepsy seizure prediction"
# Resolve a DOI to full record (title, abstract, citations, journal IF)
crossref-local search-by-doi 10.1038/nature11247
# Drive from MCP / Claude Code
crossref-local mcp serve
The image is a live capture against the local DB; the <details>
block below has a 6m55s MCP-driven demo video.
Architecture
┌──────────────────────────┐ ┌──────────────────────────┐
│ CrossRef public dump │ │ JCR / OpenAlex IF tables │
│ (~100 GB compressed) │ │ │
└──────────────┬───────────┘ └──────────────┬───────────┘
│ dois2sqlite │
▼ ▼
┌─────────────────┐ ┌──────────────┐
│ crossref.db │ ◀── joins ──▶ │ impact-factor│
│ (SQLite + FTS5) │ │ table │
└────────┬────────┘ └──────────────┘
│
▼
┌──────────────────────────────────┐
│ crossref-local — Python / CLI / MCP │
│ search · search-by-doi · cache │
│ stats · check-citations · relay │
└──────────────────────────────────┘
The DB lives entirely on disk; crossref-local is a thin facade over
SQLite + FTS5 + a small impact-factor table. No network calls during
queries; rebuild scripts under make fts-build-screen /
citations-build-screen are the only producers of state.
PyPI version Documentation Tests Coverage Python License
MCP Demo Video
Live demonstration of MCP server integration with Claude Code for epilepsy seizure prediction literature review:
- Full-text search on title, abstracts, and keywords across 167M papers (22ms response)
Why CrossRef Local?
Built for the LLM era - features that matter for AI research assistants:
| Feature | Benefit |
|---|---|
| 📝 Abstracts | Full text for semantic understanding |
| 📊 Impact Factor | Filter by journal quality |
| 🔗 Citations | Prioritize influential papers |
| ⚡ Speed | 167M records in ms, no rate limits |
Perfect for: RAG systems, research assistants, literature review automation.
Installation
pip install crossref-local
From source:
git clone https://github.com/ywatanabe1989/crossref-local
cd crossref-local && make install
Database setup (1.5 TB, ~2 weeks to build):
# 1. Download CrossRef data (~100GB compressed)
aria2c "https://academictorrents.com/details/..."
# 2. Build SQLite database (~days)
pip install dois2sqlite
dois2sqlite build /path/to/crossref-data ./data/crossref.db
# 3. Build FTS5 index (~60 hours) & citations table (~days)
make fts-build-screen
make citations-build-screen
Python API
from crossref_local import search, get, count
# Full-text search (22ms for 541 matches across 167M records)
results = search("hippocampal sharp wave ripples")
for work in results:
print(f"{work.title} ({work.year})")
# Get by DOI
work = get("10.1126/science.aax0758")
print(work.citation())
# Count matches
n = count("machine learning") # 477,922 matches
Async API:
from crossref_local import aio
async def main():
counts = await aio.count_many(["CRISPR", "neural network", "climate"])
results = await aio.search("machine learning")
CLI
crossref-local search "CRISPR genome editing" -n 5
crossref-local search-by-doi 10.1038/nature12373
crossref-local status # Configuration and database stats
With abstracts (-a flag):
$ crossref-local search "RS-1 enhances CRISPR" -n 1 -a
Found 4 matches in 128.4ms
1. RS-1 enhances CRISPR/Cas9- and TALEN-mediated knock-in efficiency (2016)
DOI: 10.1038/ncomms10548
Journal: Nature Communications
Abstract: Zinc-finger nuclease, transcription activator-like effector nuclease
and CRISPR/Cas9 are becoming major tools for genome editing...
HTTP API
Start the FastAPI server:
crossref-local relay --host 0.0.0.0 --port 31291
Endpoints:
# Search works (FTS5)
curl "http://localhost:31291/works?q=CRISPR&limit=10"
# Get by DOI
curl "http://localhost:31291/works/10.1038/nature12373"
# Batch DOI lookup
curl -X POST "http://localhost:31291/works/batch" \
-H "Content-Type: application/json" \
-d '{"dois": ["10.1038/nature12373", "10.1126/science.aax0758"]}'
# Citation endpoints
curl "http://localhost:31291/citations/10.1038/nature12373/citing"
curl "http://localhost:31291/citations/10.1038/nature12373/cited"
curl "http://localhost:31291/citations/10.1038/nature12373/count"
# Collection endpoints
curl "http://localhost:31291/collections"
curl -X POST "http://localhost:31291/collections" \
-H "Content-Type: application/json" \
-d '{"name": "my_papers", "query": "CRISPR", "limit": 100}'
curl "http://localhost:31291/collections/my_papers/download?format=bibtex"
# Database info
curl "http://localhost:31291/info"
HTTP mode (connect to running server):
# On local machine (if server is remote)
ssh -L 31291:127.0.0.1:31291 your-server
# Python client
from crossref_local import configure_http
configure_http("http://localhost:31291")
# Or via CLI
crossref-local --http search "CRISPR"
MCP Server
Run as MCP (Model Context Protocol) server:
crossref-local mcp start
Local MCP client configuration:
{
"mcpServers": {
"crossref-local": {
"command": "crossref-local",
"args": ["mcp", "start"],
"env": {
"CROSSREF_LOCAL_DB": "/path/to/crossref.db"
}
}
}
}
Remote MCP via HTTP (recommended):
# On server: start persistent MCP server
crossref-local mcp start -t http --host 0.0.0.0 --port 8082
{
"mcpServers": {
"crossref-remote": {
"url": "http://your-server:8082/mcp"
}
}
}
Diagnose setup:
crossref-local mcp doctor # Check dependencies and database
crossref-local mcp list-tools # Show available MCP tools
crossref-local mcp installation # Show client config examples
See docs/remote-deployment.md for systemd and Docker setup.
Available tools:
search- Full-text search across 167M+ paperssearch_by_doi- Get paper by DOIenrich_dois- Add citation counts and references to DOIsstatus- Database statisticscache_*- Paper collection management
Impact Factor
from crossref_local.impact_factor import ImpactFactorCalculator
with ImpactFactorCalculator() as calc:
result = calc.calculate_impact_factor("Nature", target_year=2023)
print(f"IF: {result['impact_factor']:.3f}") # 54.067
| Journal | IF 2023 |
|---|---|
| Nature | 54.07 |
| Science | 46.17 |
| Cell | 54.01 |
| PLOS ONE | 3.37 |
Citation Network
from crossref_local import get_citing, get_cited, CitationNetwork
citing = get_citing("10.1038/nature12373") # 1539 papers
cited = get_cited("10.1038/nature12373")
# Build visualization (like Connected Papers)
network = CitationNetwork("10.1038/nature12373", depth=2)
network.save_html("citation_network.html") # requires: pip install crossref-local[viz]
Performance
| Query | Matches | Time |
|---|---|---|
hippocampal sharp wave ripples |
541 | 22ms |
machine learning |
477,922 | 113ms |
CRISPR genome editing |
12,170 | 257ms |
Searching 167M records in milliseconds via FTS5.
Related Projects
openalex-local - Sister project with OpenAlex data:
| Feature | crossref-local | openalex-local |
|---|---|---|
| Works | 167M | 284M |
| Abstracts | ~21% | ~45-60% |
| Update frequency | Real-time | Monthly |
| DOI authority | ✓ (source) | Uses CrossRef |
| Citations | Raw references | Linked works |
| Concepts/Topics | ❌ | ✓ |
| Author IDs | ❌ | ✓ |
| Best for | DOI lookup, raw refs | Semantic search |
When to use CrossRef: Real-time DOI updates, raw reference parsing, authoritative metadata. When to use OpenAlex: Semantic search, citation analysis, topic discovery.
Installation
pip install crossref-local # core
pip install crossref-local[mcp] # + MCP server
From source:
git clone https://github.com/ywatanabe1989/crossref-local
cd crossref-local && make install
4 Interfaces
Python API
from crossref_local import search, get, count
# Full-text search (22ms for 541 matches across 167M records)
results = search("hippocampal sharp wave ripples")
for work in results:
print(f"{work.title} ({work.year})")
# Get by DOI
work = get("10.1126/science.aax0758")
print(work.citation())
# Count matches
n = count("machine learning") # 477,922 matches
CLI
crossref-local search "CRISPR genome editing" -n 5
crossref-local search-by-doi 10.1038/nature12373
crossref-local status # Configuration and database stats
HTTP API
See the HTTP API section above for all endpoints.
MCP Server
See the MCP Server section above for configuration.
Part of SciTeX
crossref-local is part of SciTeX.
Four Freedoms for Research
- The freedom to run your research anywhere — your machine, your terms.
- The freedom to study how every step works — from raw data to final manuscript.
- The freedom to redistribute your workflows, not just your papers.
- The freedom to modify any module and share improvements with the community.
AGPL-3.0 — because we believe research infrastructure deserves the same freedoms as the software it runs on.
Install Crossref Local in Claude Desktop, Claude Code & Cursor
unyly install crossref-localInstalls into Claude Desktop, Claude Code, Cursor & VS Code — handles npx, uvx and build-from-source repos for you.
First time? Get the CLI: curl -fsSL https://unyly.org/install | sh
Or configure manually
Run in your terminal:
claude mcp add crossref-local -- uvx crossref-localFAQ
Is Crossref Local MCP free?
Yes, Crossref Local MCP is free — one-click install via Unyly at no cost.
Does Crossref Local need an API key?
No, Crossref Local runs without API keys or environment variables.
Is Crossref Local hosted or self-hosted?
Self-hosted: the server runs locally on your machine via the install command above.
How do I install Crossref Local in Claude Desktop, Claude Code or Cursor?
Open Crossref Local on unyly.org, pick your client tab (Claude Desktop, Claude Code, Cursor) and press Install — the config is generated automatically, no JSON editing.
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