Its actually open-source. Here is the repo: https://github.com/mireklzicar/doi-reference-extractor https://github.com/mireklzicar/doi-reference-extractor APIs

Its actually open-source. Here is the repo: https://github.com/mireklzicar/doi-reference-extractor https://github.com/mireklzicar/doi-reference-extractor APIs Used OpenCitations API (v2) Endpoint: https://opencitations.net/index/api/v2/references/ https://opencitations.net/index/api/v2/references/ Purpose: Retrieves a list of all references from a paper by its DOI Data format: JSON containing cited DOIs and metadata DOI Content Negotiation Endpoint: https://doi.org/{DOI} https://doi.org/{DOI} Purpose: Fetches metadata and formatted citations for DOIs Formats: BibTeX, RIS, CSL JSON, RDF XML, etc. Implements CSL (Citation Style Language) for text-based citations Local Citation Style Files Purpose: Provides access to thousands of citation styles Storage: Pre-generated JSON files with style information