openalex

name	openalex
description	Query OpenAlex API from the command line with curl and jq for publication discovery, filtering, sorting, pagination, and PDF availability checks. Use when searching scholarly works/authors/sources, building or debugging OpenAlex queries, extracting results, or downloading available PDFs using OPENALEX_API_KEY.
compatibility	Requires curl, jq, bash, OPENALEX_API_KEY environment variable, and internet access.
license	CC BY-SA 4.0 (Creative Commons Attribution-ShareAlike 4.0 International)
metadata	{"version":"0.2","author":"Andrea Borruso <[e-mail]>","tags":["api","research","scholarly","bibliometrics","open-access","curl","jq","pdf"]}

OpenAlex

Use this skill to run reliable OpenAlex API workflows from shell.

IMPORTANT: Always write curl commands on a single line. Multi-line \ continuation breaks argument parsing in agent environments and will cause errors.

SECURITY: Never expose the actual value of OPENALEX_API_KEY anywhere — not in text responses, not in echoed commands, not in logs. Always reference it as $OPENALEX_API_KEY. If the key appears in any output, stop immediately and do not repeat it.

Definition of Done

A task is complete when:

Results

• The API returns at least one result (or a clear "no results found" message)
• Each result shows: title (display_name), year, citation count
• Output is readable — not a raw JSON blob

Process

• curl written on a single line
• api_key included in every request
• select= used to limit returned fields
• jq used to format output

PDF download (when requested)

• If PDF is available: file saved locally, path printed
• If PDF is not available: clear message, exit code 2, no crash

Quick Start

1. Export API key:

export OPENALEX_API_KEY='...'

To verify it is set without printing the value:

[[ -n "${OPENALEX_API_KEY:-}" ]] && echo "key is set" || echo "ERROR: OPENALEX_API_KEY not set"

2. Run list query (works):

curl -sS --get 'https://api.openalex.org/works' --data-urlencode 'search="data quality" AND "open government data"' --data-urlencode 'filter=type:article,from_publication_date:2023-01-01' --data-urlencode 'sort=relevance_score:desc' --data-urlencode 'per-page=200' --data-urlencode 'select=display_name,publication_year,cited_by_count,doi' --data-urlencode "api_key=$OPENALEX_API_KEY" | jq '.results[] | {title:.display_name, year:.publication_year, cited_by:.cited_by_count, doi}'

Workflow

1. Define entity endpoint (works, authors, sources, etc.).
2. Build a search block with boolean logic (AND, OR, NOT, quotes, parentheses).
3. Add structured filter constraints (type/date/language/OA/citation fields).
4. Restrict output with select (root-level fields only).
5. Page results with page or cursor=*.
6. Extract fields via jq and save/transform as needed.

Iterative Validation Workflow

Use this when building or debugging non-trivial queries.

1. Start with a toy query (per-page=5 or per-page=10) and minimal select=.
2. Manually inspect 5-10 records for relevance and field quality (display_name, year, DOI).
3. Compare a baseline and a variant before scaling:
   • baseline: filter=title.search:"..."
   • variant: search=... with same filters
4. Tune one parameter at a time (search, filter, sort, per-page, pagination mode).
5. Scale only after validation (per-page=200, then cursor=* for deep pagination).
6. Log each run: command, key parameters, result count, and quick notes.

Avoid jumping directly from a paper/spec to a full extraction script without this short validation loop.

Query Blocks

• title.search=: searches only in the title — use this by default for focused results. Must be passed inside filter=, not as a standalone parameter: filter=title.search:"your query".
• search=: full-text search across the entire document — use only when title-only matching is too restrictive.
• search.semantic=: semantic/conceptual search (costs $0.001/request; requires API key).
• filter=: exact/structured constraints; comma means AND.
• sort=: relevance_score:desc, cited_by_count:desc, publication_date:desc, etc.
• per-page=: 1..200. Default is 25 — always set per-page=200 for bulk queries (8× fewer API calls).
• page=: page number for standard pagination.
• cursor=*: deep pagination beyond first 10k records.
• select=: reduce payload; nested paths are not allowed in select.
• group_by=: aggregate results by a field (e.g. group_by=publication_year, group_by=topics.id).
• sample=: random sample of N results (e.g. sample=20). Add seed=42 for reproducibility.

Filter Syntax

Filters are comma-separated AND conditions. Within a single attribute:

Logic	Syntax	Example
AND (comma)	filter=a:x,b:y	filter=type:article,is_oa:true
OR (pipe)	filter=type:article|book	multiple values for same field
NOT (exclamation)	filter=type:!journal-article	negation
Greater than	filter=cited_by_count:>100	comparison
Less than	filter=publication_year:<2020	comparison
Range	filter=publication_year:2020-2023	inclusive range

Batch Lookup

Combine up to 50 IDs in one request using the pipe operator — avoid sequential calls:

# Batch DOI lookup (up to 50 per request)
curl -sS --get 'https://api.openalex.org/works' --data-urlencode 'filter=doi:https://doi.org/10.1/abc|https://doi.org/10.2/def' --data-urlencode 'per-page=50' --data-urlencode "api_key=$OPENALEX_API_KEY" | jq '.results[] | {title:.display_name, doi}'

Two-Step Entity Lookup

Names are ambiguous; always resolve to an OpenAlex ID first, then filter.

Step 1 — find the entity ID:

curl -sS --get 'https://api.openalex.org/authors' --data-urlencode 'search=Heather Piwowar' --data-urlencode 'per-page=5' --data-urlencode "api_key=$OPENALEX_API_KEY" | jq '.results[] | {id, display_name}'

Step 2 — use the ID in a filter:

curl -sS --get 'https://api.openalex.org/works' --data-urlencode 'filter=authorships.author.id:A5023888391' --data-urlencode 'per-page=200' --data-urlencode 'select=id,display_name,publication_year,cited_by_count' --data-urlencode "api_key=$OPENALEX_API_KEY" | jq '.results[] | {title:.display_name, year:.publication_year}'

Applies to: authors (authorships.author.id), institutions (authorships.institutions.id), sources/journals (primary_location.source.id). External IDs are also accepted: ORCID, ROR, ISSN, DOI.

PDF Retrieval

For a work ID:

1. Fetch work metadata.
2. Resolve PDF URL in this order:
   • .content_urls.pdf
   • .best_oa_location.pdf_url
   • .primary_location.pdf_url
   • first non-null .locations[].pdf_url
3. Download with api_key query parameter when source is content.openalex.org.

Output Format

When displaying results, always show display_name as the title — never use doi or id in its place.

Minimal jq for a results table:

| jq -r '.results[] | [.display_name, .publication_year, .cited_by_count, .doi] | @tsv'

Or as structured objects:

| jq '.results[] | {title: .display_name, year: .publication_year, cited_by: .cited_by_count, doi}'

CSV Export

To save results as a CSV file, use jq with @csv and include a header row:

curl -sS --get 'https://api.openalex.org/works' ... --data-urlencode "api_key=$OPENALEX_API_KEY" | jq -r '["title","year","cited_by","doi"], (.results[] | [.display_name, .publication_year, .cited_by_count, (.doi // "")]) | @csv' > results.csv

Rules:

• Use // "" for fields that may be null (e.g. doi) — @csv fails on null values.
• The header array and data array must have the same number of columns.
• Use -r (raw output) so @csv produces plain text, not JSON strings.

Error Handling

Implement exponential backoff on 403 (rate limit) and 500 (server error):

attempt 1 → wait 1s → attempt 2 → wait 2s → attempt 3 → wait 4s → attempt 4 → wait 8s

HTTP codes:

• 200 — success
• 400 — invalid parameter or filter syntax; fix the query
• 403 — rate limit exceeded; back off and retry
• 404 — entity not found
• 500 — temporary server error; retry with backoff

Endpoint Costs

With the free $1/day budget:

Request type	Cost	Daily limit
Singleton (/works/W123)	free	unlimited
List / filter	$0.0001	~10,000 requests
Search (full-text or semantic)	$0.001	~1,000 requests
PDF download (content.openalex.org)	$0.01	~100 downloads

Use select= and per-page=200 to minimize request count.

Common Pitfalls

• Do not use .id or .doi as the title field in jq output — .id is an OpenAlex URL, .doi is a DOI URL; always use .display_name for human-readable titles.
• Do not include id in select= unless you need the OpenAlex URL for follow-up lookups — it is a URL, not a title, and confuses output.
• Do not sort by relevance_score without a search query.
• Do not use nested fields in select (example: use open_access, then parse .open_access.is_oa with jq).
• Do not filter by entity names directly — use the two-step entity lookup to get the ID first.
• Do not use sequential calls for batch ID lookups — batch up to 50 with the pipe operator.
• Do not use per-page=25 (default) for bulk extraction — always set per-page=200.
• Expect some records to have no downloadable PDF.
• search= searches full text and can return loosely related results. Use title.search= when the topic must appear in the title.
• Always write curl commands on a single line — multi-line \ continuation breaks argument parsing in agent environments.
• title.search is NOT a valid standalone parameter — always pass it inside filter=: filter=title.search:"your query".
• Always include api_key=$OPENALEX_API_KEY in every request.
• Never expose the actual key value — not in text output, not in echoed commands, not in logs, and not in any other form. Always use the variable reference $OPENALEX_API_KEY.
  • To verify it is set: [[ -n "${OPENALEX_API_KEY:-}" ]] && echo "key is set" || echo "ERROR: OPENALEX_API_KEY not set".

Resources

• Query recipes and jq snippets: references/query-recipes.md
• Generic query helper: scripts/openalex_query.sh
• PDF downloader for work IDs: scripts/openalex_download_pdf.sh