crossref-rs

Query Crossref literature metadata, generate BibTeX entries, and download open-access PDFs — from the command line or inside a Nushell pipeline.

Features

• Fetch Crossref metadata by DOI with automatic Unpaywall OA enrichment
• Free-text and filtered search (year range, work type, open-access)
• PDF download via direct OA URL or EZproxy fallback
• BibTeX generation with --key-style author-year|short-title
• Automatic citation key conflict resolution (Smith2024, Smith2024a, …)
• Append to .bib file with DOI-based deduplication
• Disk response cache with configurable TTL (--no-cache to bypass)
• Multiple output formats: table (default), json, yaml, bibtex
• Nushell plugin with pipeline-friendly structured output

Installation

cargo install crossref-rs

From source:

git clone https://github.com/TonyWu20/crossref-rs
cd crossref-rs
cargo install --path .

For the Nushell plugin, register it after installation:

plugin add (which nu_plugin_crossref | get path.0)

Configuration

On first invocation without a configured email, crossref creates a default config file and prints shell-specific setup instructions. Edit the file to add your email, then re-run.

Config file: ~/.config/crossref.toml (override with --config FILE)

email = "your.name@institution.edu"      # required for Crossref polite pool
proxy = "doi-org.ezproxy.example.edu"    # optional EZproxy host for PDF fallback
default_rows = 10
cache_ttl_days = 30
# cache_dir = "/custom/cache/path"

Priority (highest to lowest):

1. --email CLI flag
2. CROSSREF_EMAIL environment variable
3. Config file
4. Built-in defaults

Other environment variables: CROSSREF_PROXY, CROSSREF_ROWS, CROSSREF_CACHE_TTL_DAYS

CLI Usage

Global flags

--config FILE        Path to config file
--email EMAIL        Override polite email  (env: CROSSREF_EMAIL)
--no-cache           Disable cache for this invocation
-f, --format FORMAT  Output format: table (default), json, yaml, bibtex
-v, --verbose        Print cache hits/misses and API details to stderr

fetch-meta

Fetch metadata for one or more DOIs.

crossref fetch-meta 10.1038/nature12373
crossref fetch-meta 10.1038/nature12373 --format json
crossref fetch-meta 10.1038/nature12373 10.1126/science.aaf7680

fetch-bib

Fetch BibTeX entries for one or more DOIs.

crossref fetch-bib 10.1038/nature12373
crossref fetch-bib 10.1038/nature12373 --key-style short-title

# Append to a .bib file (deduplicates by DOI, resolves key conflicts)
crossref fetch-bib 10.1038/nature12373 10.1126/science.1245679 --append refs.bib

search

Search Crossref for literature.

crossref search "transformer neural networks" --year-from 2020 --type journal-article --rows 5
crossref search --author "LeCun" --open-access --format json
crossref search "CRISPR" --year-from 2018 --year-to 2023 --sort published

Options:

QUERY                    Free-text query
--title TITLE            Filter by title
--author AUTHOR          Filter by author
--year-from YEAR         Earliest publication year
--year-to YEAR           Latest publication year
--type TYPE              Work type (e.g. journal-article, book-chapter)
--open-access            Only return open-access items
-n, --rows N             Number of results (default: 10)
--sort ORDER             Score (default), updated, deposited, indexed, published

pdf

Download the best available OA PDF, or fall back to an EZproxy URL or a doi.org link.

crossref pdf 10.1038/nature12373
crossref pdf 10.1038/nature12373 --output ~/papers/

config

crossref config path    # print path to active config file
crossref config show    # print current effective configuration (JSON)

cache

crossref cache prune    # remove expired entries
crossref cache clear    # wipe all cached entries

Output Formats

Nushell Plugin

After registration, all commands return structured data and compose naturally with Nushell pipelines.

# Fetch metadata — returns a record
crossref fetch-meta "10.1038/nature12373"

# Search — returns a list of records
crossref search "deep learning" --rows 20
    | where is_oa == true
    | select doi title year

# BibTeX string
crossref fetch-bib "10.1038/nature12373"

# Download PDF
crossref pdf "10.1038/nature12373" --output ~/papers/

All plugin commands accept --email to override the configured address for that call.

Library Usage

crossref_lib is the underlying Rust library and can be used directly:

use std::sync::Arc;
use crossref_lib::{client::CrossrefClient, config::Config, models::SearchQueryBuilder};

#[tokio::main]
async fn main() -> crossref_lib::Result<()> {
    let cfg = Arc::new(Config::load(Some("me@example.com"), None)?);
    let client = CrossrefClient::new(cfg)?;

    // Fetch one work (auto-enriched with Unpaywall OA data)
    let work = client.fetch_work("10.1038/nature12373").await?;
    println!("{:?}", work);

    // Search
    let query = SearchQueryBuilder::default()
        .query(Some("machine learning".into()))
        .rows(5u32)
        .build()?;
    let results = client.search(&query).await?;
    println!("Found {} results", results.total_results);
    Ok(())
}

BibTeX Details

Citation key styles

Short-title strips common stop-words (a, the, of, in, …) and takes up to four significant title words. Key conflicts are resolved automatically by appending letter suffixes: Smith2024, Smith2024a, Smith2024b, …

Entry type mapping

License

Licensed under MIT.