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Agent skill

Unpaywall API

by wentorai in wentorai/research-plugins

Find free legal full-text versions of scholarly articles via Unpaywall

MITAuto-check passedBackend & APIs

Install Unpaywall API

skills CLI
$ npx skills add wentorai/research-plugins --skill unpaywall-api -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install wentorai/research-plugins unpaywall-api --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/literature/fulltext/unpaywall-api .claude/skills/unpaywall-api && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
unpaywall-api
GitHub stars
298
Used in
1 other repo
Token cost
~1.3k tokens
SKILL.md length
494 words
Files
1
Skills in repo
405
Repo updated
First seen
Licence
MIT

At a glance

Find free legal full-text versions of scholarly articles via Unpaywall

  • Backend & APIs work in your project
  • SKILL.md covers Overview, Authentication, Core Endpoints and Rate Limits, plus 2 more sections
  • Calls curl and jq; reaches api.unpaywall.org

What it does

Unpaywall API is an agent skill from wentorai/research-plugins. Find free legal full-text versions of scholarly articles via Unpaywall

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Backend & APIs. The repository describes itself as: 350+ academic research skills, MCP configs, and plugins for Research-Claw and AI agents. The licence is MIT.

When your agent uses it

  • Backend & APIs work in your project

Example prompts

  • “/unpaywall-api”

What it can do on your machine

Read from SKILL.md and the folder at commit bf44b3c. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • curl
    • jq

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Hosts in commands or code, which the agent is likely to contact:

    • api.unpaywall.org

    Also links to:

    • unpaywall.org
    • ourresearch.org

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Unpaywall API loads about 1.3k tokens when it runs. Until then it costs about 21 tokens; SKILL.md has 494 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~21
When it runs · the whole SKILL.md, loaded when a task matches
~1.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from wentorai/research-plugins at commit bf44b3c, republished under its MIT licence (© wentorai). 494 words, ~1,329 tokens.

Download SKILL.mdSave it as .claude/skills/unpaywall-api/SKILL.md (or your agent's skills folder).
name
unpaywall-api
description
Find free legal full-text versions of scholarly articles via Unpaywall

Unpaywall API Guide

Overview

Unpaywall is a free, open database of over 40 million free scholarly articles. Built by the nonprofit OurResearch, Unpaywall indexes legal open access (OA) copies of papers from thousands of institutional repositories, preprint servers, publisher websites, and government archives. It is the most comprehensive source for finding freely available versions of paywalled academic literature.

Researchers, librarians, and tool developers use Unpaywall to locate open access copies of papers they need, assess the OA status of publications, and integrate OA discovery into their workflows. The database is updated daily, scanning repositories and publisher sites for new open access content. Unpaywall categorizes OA into types: gold (published OA), green (repository copy), hybrid (OA in subscription journal), and bronze (free to read on publisher site).

The API requires only an email address for authentication and is free for non-commercial use with a generous rate limit of 100,000 requests per day.

Authentication

Authentication is via email address passed as a query parameter. No API key or registration is needed -- just provide a valid email:

?email=your@email.com

This email is used for contact purposes only and to identify your application. The API will reject requests without a valid email address. For commercial use or higher rate limits, contact OurResearch for an API key.

Core Endpoints

DOI Lookup: Find Open Access for a Paper
  • URL: GET https://api.unpaywall.org/v2/{doi}
  • Parameters:
    ParamTypeRequiredDescription
    doistringYesThe DOI of the paper (URL-encoded in path)
    emailstringYesYour email address
  • Example:
    bash
    curl "https://api.unpaywall.org/v2/10.1038/nature12373?email=user@example.com"
  • Response: JSON with comprehensive OA information:
    • is_oa: boolean indicating if any OA version exists
    • best_oa_location: the best available OA copy with url, url_for_pdf, evidence, host_type, license, and version
    • oa_locations: array of all known OA copies
    • oa_status: gold, green, hybrid, bronze, or closed
    • title, doi, year, genre, journal_name, publisher
Show full SKILL.md (227 more words)Show less
Batch DOI Lookup: Multiple Papers
  • URL: GET https://api.unpaywall.org/v2/{doi} (repeated per DOI)
  • Parameters:
    ParamTypeRequiredDescription
    doistringYesOne DOI per request (batch via multiple requests)
    emailstringYesYour email address
  • Example:
    bash
    # Process multiple DOIs sequentially
for doi in "10.1038/nature12373" "10.1126/science.aaa8685" "10.1016/j.cell.2015.05.002"; do
  curl -s "https://api.unpaywall.org/v2/$doi?email=user@example.com" | jq '{doi: .doi, is_oa: .is_oa, oa_status: .oa_status, best_url: .best_oa_location.url}'
  sleep 0.01
done
  • Response: Same JSON structure as single lookup, for each DOI.
Data Feed: Bulk Access

For large-scale analyses, Unpaywall provides a complete database snapshot and a weekly data feed, rather than requiring millions of individual API calls. Access is available at https://unpaywall.org/products/data-feed for registered users.

Rate Limits

The API allows 100,000 requests per day (approximately 1.15 requests per second sustained). There is no strict per-second rate limit, so burst traffic is acceptable as long as the daily cap is respected. Exceeding the limit returns HTTP 429. For analyses requiring more than 100K lookups, use the Unpaywall Data Feed (database snapshot) instead.

Common Patterns

Check OA Status for a Reading List

Determine which papers in your reading list have freely available versions:

bash
curl -s "https://api.unpaywall.org/v2/10.1038/s41586-021-03819-2?email=user@example.com" | jq '{title: .title, is_oa: .is_oa, oa_status: .oa_status, pdf: .best_oa_location.url_for_pdf}'
Find the Best Available PDF

Get a direct link to the best open access PDF for a paper:

bash
curl -s "https://api.unpaywall.org/v2/10.1145/3292500.3330672?email=user@example.com" | jq '.best_oa_location | {url: .url, pdf: .url_for_pdf, version: .version, license: .license}'
Audit Open Access Compliance for a Grant

Check whether publications from a funded project comply with OA mandates:

bash
# For each publication DOI from the grant
curl -s "https://api.unpaywall.org/v2/10.1038/nature12373?email=user@example.com" | jq '{doi: .doi, title: .title, is_oa: .is_oa, oa_status: .oa_status, locations: [.oa_locations[] | {host: .host_type, license: .license, version: .version}]}'

References

© wentorai, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/literature/fulltext/unpaywall-api of wentorai/research-plugins.

Open the folder on GitHubat commit bf44b3c

Used in 1 other repository

We found 2 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in wentorai/research-plugins, which our catalogue first saw on October 7, 2026.

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Firecrawl Build Onboardingfirecrawl/firecrawl190k1 repos~1.4kAutomated safety check: NotesISC
Obsidian BasesAtmosphere/atmosphere3.8k22 repos~3.2kAutomated safety check: PassApache-2.0

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Categories

Questions about Unpaywall API

What does Unpaywall API do?

Find free legal full-text versions of scholarly articles via Unpaywall. Unpaywall API is an agent skill from wentorai/research-plugins.

When should I use Unpaywall API?

Unpaywall API fits situations like: backend & APIs work in your project.

How do I install Unpaywall API in Claude Code?

Run `npx skills add wentorai/research-plugins --skill unpaywall-api -a claude-code`. Or copy the skill folder (skills/literature/fulltext/unpaywall-api in wentorai/research-plugins) into .claude/skills/unpaywall-api in your project. Claude Code loads it when a task matches its description.

How do I install Unpaywall API in Codex?

Run `npx skills add wentorai/research-plugins --skill unpaywall-api -a codex`. Or copy the skill folder (skills/literature/fulltext/unpaywall-api in wentorai/research-plugins) into .agents/skills/unpaywall-api in your project. Codex loads it when a task matches its description.

Can I use Unpaywall API in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add wentorai/research-plugins --skill unpaywall-api -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/unpaywall-api, .gemini/skills/unpaywall-api, .github/skills/unpaywall-api and .opencode/skills/unpaywall-api in your project.

What does Unpaywall API need to run?

Going by SKILL.md and its folder, Unpaywall API needs the command-line tools its instructions call (curl and jq).

Does Unpaywall API access the network?

SKILL.md names 3 domains. In commands or code: api.unpaywall.org; the agent is likely to contact it when it follows the instructions. As links in the text: unpaywall.org and ourresearch.org. This is read from the text; nothing was executed.

Is Unpaywall API safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Unpaywall API use?

Unpaywall API is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Unpaywall API use?

About 1.3k tokens (SKILL.md is roughly 5.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Unpaywall API?

Skills that share tags, products or a category with Unpaywall API: Configuring Horizon (coollabsio/coolify, 63k stars), Nestjs Best Practices (rolling-scopes/rsschool-app, 10k stars), Sub2API Admin (Wei-Shaw/sub2api, 44k stars) and Firecrawl Build Onboarding (firecrawl/firecrawl, 190k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Unpaywall API?

wentorai (a GitHub user) maintains it in wentorai/research-plugins, which has 298 GitHub stars. The repository holds 405 skills in this directory. The repository was last updated on June 19, 2026.

Source: wentorai/research-plugins on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.