# Unpaywall

**Canonical:** https://apis.io/providers/unpaywall/  
**Website:** https://unpaywall.org  
**APIs profiled:** 2

The Unpaywall REST API gives anyone free, programmatic access to the Unpaywall database of open access scholarly articles. The database covers over 120 million articles with Crossref DOIs and provides free, legal full-text links where available, with metadata on OA status (gold, hybrid, bronze, green), host type (publisher, repository), version (published, accepted, submitted), and license information.

## Kin Score — 26.9 / 100 (thin)

Scored 2026-08-20 under rubric 0.12.0. Trend: flat (+0.0 from 26.9).

| Facet | Score |
|---|---|
| Discoverability | 68.5 |
| Contract Quality | 67.1 |
| Governance | 25.0 |
| Contract Governance | 25.0 |
| Operational Transparency | 10.5 |
| Developer Ergonomics | 0.0 |
| Commercial Clarity | 0.0 |
| Access Clarity | 0.0 |

Regulatory layer — **Education & Research**: 20.4 (matched via tags).

## Agent readiness — 39.8 (agent-ready)

| Dimension | Value |
|---|---|
| Spec Presence | yes |
| Agentic Access | derived |
| Reversibility Documented | na |
| MCP Server | no |
| Auth Clarity | no |
| Idempotency | na |
| Error Semantics | verified |
| OpenAPI Examples | verified |
| Rate Limit Signal | documented |
| Event Surface Described | no |
| Agent Skills | no |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | na |

## Access

Freemium — onboarding: unknown, pricing: freemium, trial: no (confidence: medium).

## APIs (2)

- **Unpaywall DOI Lookup API** — Look up open access status by DOI
- **Unpaywall Search API** — Search articles by title

## Agentic access (1)

- **Unpaywall Agentic Access** — 2 operations

## Security (1)

- **Unpaywall Domain Security** — TLSv1.3

## Plans (1)

- **Unpaywall Plans Pricing**

## Tags

Open Access, Scholarly Articles, Research, Academic, Libraries, DOI, Science

---

Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/unpaywall/). Scores are computed from the provider's own public artifacts under a published rubric.