Agent skill

Opencitations API

by wentorai in wentorai/research-plugins

Query open citation data and reference networks via OpenCitations

Install Opencitations API

skills CLI

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

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

GitHub CLI

$ gh skill install wentorai/research-plugins opencitations-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/metadata/opencitations-api .claude/skills/opencitations-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/

Paste into Claude Code

Install the "opencitations-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/opencitations-api into .claude/skills/opencitations-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "opencitations-api", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/opencitations-api

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add wentorai/research-plugins --skill opencitations-api -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins opencitations-api --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/literature/metadata/opencitations-api .agents/skills/opencitations-api && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "opencitations-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/opencitations-api into .agents/skills/opencitations-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "opencitations-api", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add wentorai/research-plugins --skill opencitations-api -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins opencitations-api --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/literature/metadata/opencitations-api .cursor/skills/opencitations-api && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "opencitations-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/opencitations-api into .cursor/skills/opencitations-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "opencitations-api", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/wentorai/research-plugins.git --path skills/literature/metadata/opencitations-api

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add wentorai/research-plugins --skill opencitations-api -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins opencitations-api --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/literature/metadata/opencitations-api .gemini/skills/opencitations-api && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "opencitations-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/opencitations-api into .gemini/skills/opencitations-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "opencitations-api", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install wentorai/research-plugins opencitations-api

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add wentorai/research-plugins --skill opencitations-api -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/literature/metadata/opencitations-api .github/skills/opencitations-api && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "opencitations-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/opencitations-api into .github/skills/opencitations-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "opencitations-api", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add wentorai/research-plugins --skill opencitations-api -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install wentorai/research-plugins opencitations-api --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/wentorai/research-plugins.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/literature/metadata/opencitations-api .opencode/skills/opencitations-api && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "opencitations-api" agent skill from https://github.com/wentorai/research-plugins/tree/main/skills/literature/metadata/opencitations-api into .opencode/skills/opencitations-api/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "opencitations-api", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: opencitations-api
GitHub stars: 298
Used in: 1 other repo
Token cost: ~1.5k tokens
SKILL.md length: 531 words
Files: 1
Skills in repo: 405
Repo updated: Jun 19, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Query open citation data and reference networks via OpenCitations

Tasks that involve Citation management
SKILL.md covers Overview, Authentication, Core Endpoints and Rate Limits, plus 2 more sections
Calls curl and jq; reaches api.opencitations.net

What it does

Opencitations API is an agent skill from wentorai/research-plugins. Query open citation data and reference networks via OpenCitations

Its SKILL.md is about 1.5k 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 Research & Science, covering Citation management. 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

Tasks that involve Citation management

Example prompts

“/opencitations-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.opencitations.net
Also links to:
- opencitations.net
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

Opencitations API loads about 1.5k tokens when it runs. Until then it costs about 21 tokens; SKILL.md has 531 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: ~1.5k

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). 531 words, ~1,490 tokens.

Download SKILL.mdSave it as .claude/skills/opencitations-api/SKILL.md (or your agent's skills folder).

name: opencitations-api
description: Query open citation data and reference networks via OpenCitations

OpenCitations API Guide

Overview

OpenCitations is an independent infrastructure organization dedicated to open scholarship and the publication of open bibliographic and citation data. Its main product, the OpenCitations Index of Crossref open DOI-to-DOI citations (COCI), contains over 1.6 billion citation relationships harvested from CrossRef metadata. This makes it the largest fully open citation dataset in the world.

The OpenCitations API allows researchers to programmatically access citation and reference data for any DOI in the index. This is valuable for citation network analysis, bibliometric research, impact assessment, and building literature discovery tools. Unlike proprietary citation databases (Web of Science, Scopus), OpenCitations data is fully open under a CC0 public domain dedication.

The API is free, requires no authentication, and has no published rate limits. It returns data in JSON or CSV format, making it easy to integrate into data analysis pipelines.

Authentication

No authentication required. The OpenCitations API is fully open and free. No API key, registration, or email is needed. There are no published rate limits, but users should implement reasonable request pacing for large-scale queries. For bulk data access, download the complete COCI dataset from https://opencitations.net/download.

Core Endpoints

Citations: Find Papers That Cite a DOI

URL: GET https://api.opencitations.net/index/v1/citations/{doi}
Parameters:
Param Type Required Description
doi string Yes The DOI of the cited paper (URL path parameter)
format string No Response format header: application/json or text/csv

Param	Type	Required	Description
doi	string	Yes	The DOI of the cited paper (URL path parameter)
format	string	No	Response format header: application/json or text/csv

Example:

bash

curl "https://api.opencitations.net/index/v1/citations/10.1038/nature12373"

Response: JSON array of citation objects, each containing:
- oci: OpenCitations Identifier for the citation link
- citing: DOI of the citing paper
- cited: DOI of the cited paper (the input DOI)
- creation: date the citation was first recorded
- timespan: time between publication of citing and cited papers
- journal_sc: whether citing and cited are in the same journal (self-citation indicator)
- author_sc: whether any author appears in both papers (author self-citation indicator)

References: Find Papers Cited by a DOI

URL: GET https://api.opencitations.net/index/v1/references/{doi}
Parameters:
Param Type Required Description
doi string Yes The DOI of the paper whose references to retrieve

Param	Type	Required	Description
doi	string	Yes	The DOI of the paper whose references to retrieve

Example:

bash

curl "https://api.opencitations.net/index/v1/references/10.1038/nature12373"

Response: JSON array of reference objects with the same structure as citations, where citing is the input DOI and cited are the referenced papers.

Show full SKILL.md (190 more words)Show less

Metadata: Retrieve Paper Metadata

URL: GET https://api.opencitations.net/index/v1/metadata/{doi}
Parameters:
Param Type Required Description
doi string Yes The DOI to look up (supports multiple DOIs separated by __)

Param	Type	Required	Description
doi	string	Yes	The DOI to look up (supports multiple DOIs separated by __)

Example:

bash

curl "https://api.opencitations.net/index/v1/metadata/10.1038/nature12373"

Response: JSON array with metadata including title, author, year, source_title (journal), volume, issue, page, doi, citation_count, and reference.

Citation Count: Quick Count Lookup

URL: GET https://api.opencitations.net/index/v1/citation-count/{doi}
Parameters:
Param Type Required Description
doi string Yes The DOI to check

Param	Type	Required	Description
doi	string	Yes	The DOI to check

Example:

bash

curl "https://api.opencitations.net/index/v1/citation-count/10.1038/nature12373"

Response: JSON with count field indicating the number of citations in the index.

Rate Limits

No published rate limits. OpenCitations does not enforce strict API quotas. The service runs on academic infrastructure, so users should be respectful. Best practices include pacing requests to 1-5 per second for sustained queries, caching results, and using the bulk dataset download for large-scale network analyses. The API may return HTTP 503 under heavy load.

Common Patterns

Build a Citation Network

Map the citation relationships around a seminal paper:

bash

# Get all papers citing the target paper
curl -s "https://api.opencitations.net/index/v1/citations/10.1145/3292500.3330672" | jq '.[].citing'

# Get all papers referenced by the target paper
curl -s "https://api.opencitations.net/index/v1/references/10.1145/3292500.3330672" | jq '.[].cited'

Detect Self-Citations

Filter out self-citations when computing impact metrics:

bash

curl -s "https://api.opencitations.net/index/v1/citations/10.1038/nature12373" | jq '[.[] | select(.author_sc == "no")] | length'

Compare Citation Counts Across Papers

Retrieve citation counts for multiple papers in a batch:

bash

# Multiple DOIs separated by double underscore
curl -s "https://api.opencitations.net/index/v1/metadata/10.1038/nature12373__10.1126/science.aaa8685__10.1016/j.cell.2015.05.002" | jq '.[] | {doi: .doi, title: .title, citations: .citation_count}'

References

Official documentation: https://opencitations.net/index/api/v1
OpenCitations data model: https://opencitations.net/model
COCI dataset download: https://opencitations.net/download

Files

Just SKILL.md in skills/literature/metadata/opencitations-api of wentorai/research-plugins.

Open the folder on GitHubat commit bf44b3c

Used in 1 other repository

We found 1 copy 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.

brycewang-stanford/Auto-Empirical-Research-Skillsskills/43-wentorai-research-plugins/skills/literature/metadata/opencitations-api

Compare with similar skills

Opencitations API next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Opencitations API compared with similar skills
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Opencitations API this skillwentorai/research-plugins	298	1 repos	~1.5k	Automated safety check: Pass	MIT	3 mo ago
Content Research Writerweapp-tailwindcss/weapp-tailwindcss	1.9k	25 repos	~3.5k	Automated safety check: Pass	MIT	today
NetworkxzLanqing/codex-claude-academic-skills	4.6k	16 repos	~3.2k	Automated safety check: Pass	BSD-3-Clause	4 mo ago
Citation Verification GuideGalaxy-Dawn/claude-scholar	5.7k	3 repos	~1.9k	Automated safety check: Pass	MIT	15 days ago
Systematic Review ScreenerImbad0202/academic-research-skills	51k	—	~8.4k	Automated safety check: Pass	Custom licence	5 days ago
Literature Reviewneflibata-feng/MyArxiv-Agent	126	21 repos	~5.9k	Automated safety check: Notes	MIT	yesterday

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Questions about Opencitations API

What does Opencitations API do?

Query open citation data and reference networks via OpenCitations. Opencitations API is an agent skill from wentorai/research-plugins.

When should I use Opencitations API?

Opencitations API fits situations like: tasks that involve Citation management.

How do I install Opencitations API in Claude Code?

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

How do I install Opencitations API in Codex?

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

Can I use Opencitations 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 opencitations-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/opencitations-api, .gemini/skills/opencitations-api, .github/skills/opencitations-api and .opencode/skills/opencitations-api in your project.

What does Opencitations API need to run?

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

Does Opencitations API access the network?

SKILL.md names 2 domains. In commands or code: api.opencitations.net; the agent is likely to contact it when it follows the instructions. As links in the text: opencitations.net. This is read from the text; nothing was executed.

Is Opencitations 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 Opencitations API use?

Opencitations 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 Opencitations API use?

About 1.5k tokens (SKILL.md is roughly 6k 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 Opencitations API?

Skills that share tags, products or a category with Opencitations API: Content Research Writer (weapp-tailwindcss/weapp-tailwindcss, 1.9k stars), Networkx (zLanqing/codex-claude-academic-skills, 4.6k stars), Citation Verification Guide (Galaxy-Dawn/claude-scholar, 5.7k stars) and Systematic Review Screener (Imbad0202/academic-research-skills, 51k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Opencitations 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.

Install Opencitations API

Facts

At a glance

What it does

When your agent uses it

Example prompts

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

OpenCitations API Guide

Overview

Authentication

Core Endpoints

Citations: Find Papers That Cite a DOI

References: Find Papers Cited by a DOI

Metadata: Retrieve Paper Metadata

Citation Count: Quick Count Lookup

Rate Limits

Common Patterns

Build a Citation Network

Detect Self-Citations

Compare Citation Counts Across Papers

References

Files

Used in 1 other repository

Compare with similar skills

Similar skills

More from wentorai/research-plugins

Related

Questions about Opencitations API