GET /subfields

openalex.org:openalex-api

Summary: List subfields
Operation ID: listSubfields
Auth: unknown
Description

Get a list of subfields (third-level topic categories). There are 254 subfields spread across 26 fields.

Parameters (10)

api_key (string, query, required)

Your OpenAlex API key (required). Get a free key at https://openalex.org/settings/api

cursor (string, query, optional)

Cursor for deep pagination. Use `cursor=*` to start, then use the `next_cursor` from the response.

filter (string, query, optional)

Filter subfields. Examples: `field.id:17`, `domain.id:3`, `works_count:>100000` See [all Subfield fields](/api-reference/subfields#available-filter-sort-and-group_by-fields).

group_by (string, query, optional)

Group by: `field.id`, `domain.id` See [all Subfield fields](/api-reference/subfields#available-filter-sort-and-group_by-fields).

page (integer, query, optional)

Page number for pagination. Use cursor for deep pagination beyond 10,000 results.

Constraints: {'minimum': 1}

per_page (integer, query, optional, default: 25)

Number of results per page (1-100, default 25)

Constraints: {'minimum': 1, 'maximum': 100}

sample (integer, query, optional)

Return a random sample of N results (max 10,000). Cannot be used with sort or page.

Constraints: {'maximum': 10000}

search (string, query, optional)

Full-text search across titles, abstracts, and other text fields. Example: `search=machine learning`

select (string, query, optional)

Comma-separated list of fields to return. Reduces response size. Example: `select=id,display_name,cited_by_count`

sort (string, query, optional)

Sort by: `works_count`, `cited_by_count`. Prefix with `-` for descending. See [all Subfield fields](/api-reference/subfields#available-filter-sort-and-group_by-fields).

Examples (3)

TitleTypeURLAction
List subfields with pagination curl https://api.openalex.org/subfields?per_page=50&page=1
Filter subfields by field ID curl https://api.openalex.org/subfields?filter=field.id:17
Search subfields with sorting curl https://api.openalex.org/subfields?search=machine%20learning&sort=works_count

Probe History

Latency

Status Codes

TimeStatusLatencySize
2026-03-23 10:44:22.426789 200 1277ms
2026-03-23 10:13:51.273115 200 807ms
2026-03-23 09:18:44.843731 200 442ms 1.4MB

Response Changes

WhenOldNew
2026-03-23 10:13:51.273115 6f439f06dd62 d802854086dd
2026-03-23 10:44:22.426789 d802854086dd c1eeffbca5d4