# CiteShape

> Paste a DOI, ORCID iD, ISBN or arXiv ID: validated, resolved, and formatted as APA, BibTeX and RIS. CiteShape finds the identifier in whatever you paste (URL, "doi:", reference text), normalises it, validates check digits (ORCID ISO 7064, ISBN-10/13), resolves authoritative metadata from Crossref, ORCID and arXiv, and emits APA-style, BibTeX and RIS citations. Retrieved facts are kept separate from your input, and nothing missing is guessed.

Part of usefulweb.site (https://usefulweb.site/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://citeshape.usefulweb.site/ (interactive tool at https://citeshape.usefulweb.site/tool)
- JSON API: POST https://citeshape.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://citeshape.usefulweb.site/api/v1/tool)
- OpenAPI: https://citeshape.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://citeshape.usefulweb.site/mcp - tool `citeshape`

## Inputs
- identifier (text, required): DOI, ORCID iD, ISBN or arXiv ID
- resolve (boolean): Look up metadata online (Crossref / ORCID / arXiv)

## Method
- Detection order: DOI (10.prefix/suffix, also in doi.org URLs) → ORCID iD → arXiv ID → ISBN. DOIs are lower-cased (DOIs are case-insensitive).
- ORCID: ISO 7064 MOD 11-2 check digit. ISBN-10: weighted sum mod 11; ISBN-13: alternating 1/3 weights mod 10. ISBN-10 is converted to ISBN-13 with prefix 978.
- Resolution: DOI → api.crossref.org/works/{doi}; ORCID → pub.orcid.org/v3.0/{id}/record (JSON); arXiv → export.arxiv.org/api/query. ISBN metadata is not resolved (no open authoritative registry).
- Citations are generated only from retrieved metadata; APA output follows APA 7 reference structure for author list, year, title, container, volume(issue), pages and DOI link.