# DOI Retraction & Academic Citation Verification API

**FactStamp** (`agents.factstamp.dev`) verifies academic DOIs, arXiv identifiers, cited paper titles, and retraction status deterministically against [Crossref](https://www.crossref.org/), [arXiv](https://arxiv.org/), and [Retraction Watch](https://www.crossref.org/services/retraction-watch/)—with no LLM in the verdict path. A recent [University of Turku / Columbia audit](https://www.utu.fi/en/news/news/fake-references-are-not-only-a-medical-problem-new-audit-finds-them-across-physics) of 21.6M references found fabricated-DOI rates climbing to **23.0 per 10,000 papers** in Q1 2026, while the [Charlotin AI Hallucination Cases database](https://www.damiencharlotin.com/hallucinations/) tracks over 1,260 legal filings with hallucinated citations. FactStamp's `verify_citation` tool returns `verified`, `contradicted`, or `unknown` with an offline-verifiable **Ed25519 receipt** for **US$0.02** per call (or **US$0.01/item** in `verify_bulk`).

## Verify a DOI or Citation (WebMCP-Enabled)

Tool: `factstamp_verify_citation_form` — Use when an agent or researcher wants to verify whether a DOI or arXiv ID exists, matches its cited title, and has not been retracted.

Submits: `POST https://agents.factstamp.dev/citation`

- **DOI or arXiv ID:**
- `doi` — `text, required`, placeholder `e.g. 10.1145/3658644.3690283`
- **Cited Title (optional):**
- `title` — `text`, placeholder `Optional title to cross-check`
- **Submit:** Verify Citation

## Citation Verification Comparison

| Tool | Title-to-DOI Match | Retraction Watch Check | Signed Audit Receipt |
| --- | --- | --- | --- |
| **FactStamp `verify_citation`** | Yes (deterministic string/record match) | Yes | Ed25519 JCS v2 receipt (US$0.02) |
| Raw Crossref REST API | Manual parsing required | Requires separate Retraction Watch lookup | Unsigned JSON |

Test an offline receipt at `GET https://agents.factstamp.dev/receipt/selftest` or integrate `factstamp/watch-action` on `.bib` files in CI.