Citationchaser

Introduction

Citationchaser (CC) (or citationchaser) is an open-source tool designed to automate citation chasing (also called pearl growing, reference searching, or citation mining) in academic research, particularly for systematic reviews, evidence synthesis, and comprehensive literature searching. CC helps researchers efficiently find more relevant studies by:Backward citation chasing — retrieving the references (articles cited by) in a starting set of papers.

Forward citation chasing — retrieving articles that cite the starting papers

This supplements traditional database keyword searches by exploiting citation networks to discover thematically related work, including studies that may use different terminology but are still relevant.Key FeaturesIt uses the Lens.org scholarly API (which aggregates data from PubMed, PubMed Central, Crossref, CORE, and formerly Microsoft Academic Graph) to perform these searches at scale.

Available in two main forms:An R package (for users comfortable with R; installable from CRAN or GitHub).
A user-friendly Shiny web app (no coding required) at: https://estech.shinyapps.io/citationchaser/
You can input seed articles via:DOI list
Manual entry
RIS/BibTeX file upload (exported from tools like EndNote, Zotero, etc.)

Outputs results as exportable RIS files (compatible with reference managers) or dataframes (in the R package version).
It supports deduplication and transparent, reproducible workflows — important for systematic review methods reporting.

Background

Developed by Neal R. Haddaway and colleagues, it was first released around 2021 and described in detail in a 2022 open-access paper: Haddaway NR, Grainger MJ, Gray CT. Citationchaser: A tool for transparent and efficient forward and backward citation chasing in systematic searching. Research Synthesis Methods. 2022;13(4):533-545. doi:10.1002/jrsm.1563

The tool is hosted on GitHub at https://github.com/nealhaddaway/citationchaser and has become widely recommended in university library guides and evidence synthesis communities (often compared to tools like Connected Papers, Research Rabbit, LitMaps, or Citation Gecko, though citationchaser focuses more on batch processing and systematic-review-style transparency). CC is useful in that it uses Lens.org for coverage via free API access (you may need a free Lens.org API token for heavy use or the R package version). Note: if you're doing a systematic review or scoping review and want to quickly expand your pool of potentially relevant papers via citation links without manually checking hundreds of references one by one, citationchaser is an option.