OpenAlex at https://api.openalex.org is an open index of scholarly works, authors, institutions, and topics, with citation links between them.
None. Adding [email protected] gets you into the faster polite pool.
Full reference: https://docs.openalex.org/
curl "https://api.openalex.org/works?search=attention%20is%20all%20you%20need&per-page=1&select=id,display_name,publication_year,cited_by_count"{
"meta": {
"count": 3097367,
"db_response_time_ms": 486,
"page": 1,
"per_page": 1,
"groups_count": null,
"x_query": {
"oql": "works where full text has (attention is all you need)",
"oqo": {
"get_rows": "works",
"filter_rows": []
},
"url": "/works?filter=fulltext.search:attention is all you need&per_page=1"
},
"cost_usd": 0.001
},
"results": [
{
"id": "https://openalex.org/W2626778328",
"display_name": "Attention Is All You Need",
"publication_year": 2025,
"cited_by_count": 7660
}
],
"group_by": []
}curl "https://api.openalex.org/authors?search=yoshua%20bengio&per-page=1&select=id,display_name,works_count,cited_by_count"{
"meta": {
"count": 96,
"db_response_time_ms": 124,
"page": 1,
"per_page": 1,
"groups_count": null,
"x_query": {
"oql": "authors where text has (yoshua bengio)",
"oqo": {
"get_rows": "authors",
"filter_rows": []
},
"url": "/authors?filter=text.search:yoshua bengio&per_page=1"
},
"cost_usd": 0.001
},
"results": [
{
"id": "https://openalex.org/A5086198262",
"display_name": "Yoshua Bengio",
"works_count": 1216,
"cited_by_count": 476404
}
],
"group_by": []
}group_by returns counts instead of records.
curl "https://api.openalex.org/works?filter=title.search:transformer&group_by=publication_year"{
"meta": {
"count": 178183,
"db_response_time_ms": 54,
"page": 1,
"per_page": 200,
"groups_count": 143,
"x_query": {
"oql": "works where title has (transformer) group by year",
"oqo": {
"get_rows": "works",
"filter_rows": [],
"group_by": []
},
"url": "/works?filter=display_name.search:transformer&group_by=publication_year"
},
"cost_usd": 0.0001
},
"group_by": [
{
"key": "2026",
"key_display_name": "2026",
"count": 30488
},
{
"key": "2025",
"key_display_name": "2025",
"count": 29728
}
]
}