API Quick Reference

Base URL: https://api.openalex.org | Auth: free API key (get one here) passed as ?api_key=YOUR_KEY | Rate limits: 100,000 credits/day, max 100 req/s

Entities

Entity	Count	Canonical ID	Endpoint
Works	240 M+	DOI	`/works`
Authors	—	ORCID	`/authors`
Sources	249 K	ISSN-L	`/sources`
Institutions	109 K	ROR ID	`/institutions`
Topics	~4,500	—	`/topics`
Publishers	~10 K	Wikidata ID	`/publishers`
Funders	~32 K	—	`/funders`

Key operations

Get a single entity

GET /works/W2741809807
GET /works/https://doi.org/10.7717/peerj.4375
GET /authors/https://orcid.org/0000-0003-1613-5981

Accepts OpenAlex IDs, DOIs, ORCIDs, ROR IDs, ISSN-Ls, and Wikidata IDs. Costs 0 credits.

List entities (paginated)

GET /works?per-page=50&page=2

Default 25/page, max 200. Basic paging supports up to 10,000 results. For larger sets use cursor paging: start with ?cursor=* and follow next_cursor.

Filter

GET /works?filter=publication_year:2024,cited_by_count:>100,open_access.is_oa:true

Operator	Syntax	Example
AND	comma	`field1:val1,field2:val2`
OR	pipe	`type:article\\|review`
NOT	`!`	`country_code:!us`
Inequality	`<` / `>`	`cited_by_count:>50`
Date range	`from_` / `to_`	`from_publication_date:2020-01-01`

Search

GET /works?search=machine+learning

Searches titles, abstracts, and fulltext. Supports AND, OR, NOT, exact phrases in quotes, and .no_stem mode. Results ranked by relevance_score.

Sort

GET /works?sort=cited_by_count:desc

Sort fields: display_name, cited_by_count, works_count, publication_date, relevance_score (search only).

Group by

GET /works?group_by=type

Returns faceted counts instead of individual results.

Select fields

GET /works?select=id,doi,display_name,cited_by_count

Reduces the response to only the requested root-level fields.

Semantic search

GET /find/works?query=effects+of+climate+change+on+crop+yields

AI-powered similarity search across ~217 M works using vector embeddings. Returns results with similarity scores (0–1). Supports POST for queries up to 10,000 characters.

Credit costs

Operation	Credits
Single entity lookup	0
List query	1
Search	10
Semantic search (`/find/works`)	1,000
Content download (PDF/XML)	100

Sample record

A single work fetched via GET /works/W2741809807:

{
  "id": "https://openalex.org/W2741809807",
  "doi": "https://doi.org/10.7717/peerj.4375",
  "title": "The state of OA: a large-scale analysis of the prevalence and impact of Open Access articles",
  "publication_year": 2018,
  "type": "book-chapter",
  "open_access": {
    "is_oa": true,
    "oa_status": "gold",
    "oa_url": "https://doi.org/10.7717/peerj.4375"
  },
  "cited_by_count": 1149,
  "primary_topic": {
    "id": "https://openalex.org/T10102",
    "display_name": "scientometrics and bibliometrics research",
    "subfield": { "display_name": "Statistics, Probability and Uncertainty" },
    "field": { "display_name": "Decision Sciences" },
    "domain": { "display_name": "Social Sciences" }
  }
}