Collections

A collection is a private, named list of OpenAlex entities of one type — for example, “Papers I’m tracking for this grant”, “Authors at my consortium”, or “Journals I publish in”. Collections give you a single ID you can drop into the filter parameter anywhere in the API, instead of pasting hundreds of OpenAlex IDs into every request.

Collections are private to the user who creates them. Manage them via authenticated requests against user.openalex.org, and use the collection: filter against api.openalex.org — both authenticated with your OpenAlex API key in the Authorization: Bearer header. You can only filter on collections you own.

Concepts

Property	Value
One entity type per collection	`works`, `authors`, `sources`, `institutions`, `topics`, `sdgs`, `funders`, `publishers`, `keywords`, or `concepts`
Max entities per collection	1,000
Max collections per user	100
Display-name length	1–30 characters; case-insensitive unique per user
Description length	0–500 characters
ID shape	`col_` followed by 10 alphanumeric characters

A collection holds entities of a single type. To track works and the authors of those works, create two collections.

Creating a collection

The easiest way to create a collection is in the OpenAlex web UI at openalex.org:

Run a search.
Tick the rows you want to save (or use the master checkbox to select the whole page).
Click the folder icon in the results toolbar → Create a new collection.

You can also paste a list of IDs or DOIs straight into the create-collection wizard at https://openalex.org/settings/collections. To create one programmatically, POST to /me/collections:

POST https://user.openalex.org/me/collections
Authorization: Bearer <your-api-key>
Content-Type: application/json

{
  "display_name": "My altmetrics papers",
  "entity_type": "works",
  "description": "Papers I'm tracking for the altmetrics review",
  "entity_ids": [
    "https://openalex.org/W2755968057",
    "https://openalex.org/W4404012345"
  ]
}

entity_ids is optional — you can create an empty collection and add entities later. IDs may be supplied in full-URL form (https://openalex.org/W123…) or short form (W123…); the API normalizes them. Every ID must match the collection’s entity_type — adding A123… to a works collection returns a 400 naming the offending ID. A successful create returns 201 with the saved collection:

{
  "id": "col_beNWUTw6qY",
  "user_id": "user-TSamuHxDbnhn",
  "entity_type": "works",
  "display_name": "My altmetrics papers",
  "description": "Papers I'm tracking for the altmetrics review",
  "entity_count": 2,
  "created_at": "2026-05-26T14:00:00",
  "updated_at": "2026-05-26T14:00:00"
}

Filtering search results by collection

Once a collection exists, drop its ID into any search on the matching entity type using the collection: filter:

# Every work in the col_beNWUTw6qY collection
GET https://api.openalex.org/works?filter=collection:col_beNWUTw6qY
Authorization: Bearer <your-api-key>

This works on every entity type the collection system supports — /works, /authors, /sources, /institutions, /topics, /sdgs, /funders, /publishers, /keywords, /concepts — as long as the collection and the endpoint match. Filtering an authors collection on /works returns a 400:

collection col_beNWUTw6qY is type 'authors', not valid for /works

The collection ID resolves to the underlying entity IDs at query time, so the filter combines normally with other filters and with sorting, grouping, selecting, and pagination:

# Open-access papers in this collection, newest first
GET https://api.openalex.org/works?filter=collection:col_beNWUTw6qY,is_oa:true&sort=publication_date:desc

Negation

Prepend ! to exclude the entities in the collection instead of including them:

GET https://api.openalex.org/works?filter=collection:!col_beNWUTw6qY

Limits

One collection: filter per request. Repeated or |-OR’d collection values return a 400. To combine collections, snapshot the resolved IDs client-side and pass them via the openalex: filter.
Per-request entity-list ceiling: 10,000. With the per-collection cap of 1,000 entities, a single collection is always within budget.
Authentication required. Pass your OpenAlex API key in the Authorization: Bearer … header. Anonymous requests return 401; requests by a user who doesn’t own the collection return 403.

The collection: filter above matches a collection against the endpoint of the same type — a sources collection on /sources, an authors collection on /authors. But collections are often most useful across types: filtering one kind of entity by a collection of a different kind. Any filter field whose value is an OpenAlex ID also accepts a col_… collection of the matching type. OpenAlex resolves the collection to its member IDs at query time and matches that field against them — so the collection ID behaves exactly like a value for that field. Example — the library-subscription workflow. A librarian builds a sources collection of the ~1,000 journal IDs in their Elsevier (or Wiley, Springer, …) package, then filters works by it through the primary_location.source.id field:

# Every work published in a journal in your subscription collection
GET https://api.openalex.org/works?filter=primary_location.source.id:col_beNWUTw6qY
Authorization: Bearer <your-api-key>

Because the collection resolves to ordinary field values, it composes with every other filter, plus sorting, grouping, selecting, and pagination. For example, “open-access works from 2024 in my subscribed journals, grouped by author institution”:

GET https://api.openalex.org/works?filter=primary_location.source.id:col_beNWUTw6qY,is_oa:true,publication_year:2024&group_by=authorships.institutions.id
Authorization: Bearer <your-api-key>

The same pattern works for any ID-valued filter field, on any endpoint:

Filter clause	Collection type	Meaning
`/works?filter=primary_location.source.id:col_…`	`sources`	Works published in these journals/sources
`/works?filter=authorships.author.id:col_…`	`authors`	Works by any of these authors
`/works?filter=authorships.institutions.id:col_…`	`institutions`	Works affiliated with these institutions
`/works?filter=primary_topic.id:col_…`	`topics`	Works on these topics
`/works?filter=funders.id:col_…`	`funders`	Works funded by these funders

This covers the ID-valued fields on /works, /authors, /sources, and /institutions — including author and institution fields such as last_known_institutions.id and affiliations.institution.id.

Type matching

The collection’s type must match the type the filter field expects. A sources collection works on primary_location.source.id but not on authorships.author.id; a mismatch returns a 400 naming both sides:

collection col_beNWUTw6qY is type 'sources', not valid for the `authorships.author.id` filter (expects 'authors').

A field that doesn’t take an entity ID (for example a date or boolean field) can’t take a collection at all:

The `publication_year` filter does not support cross-type collection references (col_...). Use a same-type `collection:` filter or a literal value list.

Negation

Prepend ! to the collection ID to exclude its members, just like any other filter value:

# Works NOT published in your subscribed journals
GET https://api.openalex.org/works?filter=primary_location.source.id:!col_beNWUTw6qY
Authorization: Bearer <your-api-key>

Limits

One collection per filter field. You can’t OR two collections onto the same field (field:col_a|col_b) or repeat the field with a second collection — either returns a 400. Use one collection per field; different fields in the same request can each carry their own collection.
Don’t mix a collection with literal IDs in one clause. primary_location.source.id:col_…|S12345 returns a 400. Pass the collection alone, or pass literal IDs alone.
The per-collection cap of 1,000 entities still applies, and a single request resolves to at most 10,000 entity IDs across all of its collection filters.

Managing collections

All endpoints below live on user.openalex.org and require your OpenAlex API key in the Authorization: Bearer header. Anonymous requests return 401; requests for a collection owned by another user return 403 (admins bypass this).

List your collections

GET https://user.openalex.org/me/collections

Supports ?page= and ?per_page= (max 100). Pass ?entity_id=W2755968057 to filter to collections that contain a specific entity — used by the collection-chip strip on entity pages in the OpenAlex UI. Response:

{
  "meta": {
    "page": 1, "per_page": 25, "total_count": 3, "total_pages": 1
  },
  "results": [
    {
      "id": "col_beNWUTw6qY",
      "user_id": "user-TSamuHxDbnhn",
      "entity_type": "works",
      "display_name": "My altmetrics papers",
      "description": "Papers I'm tracking for the altmetrics review",
      "entity_count": 4,
      "created_at": "2026-05-20T16:00:00",
      "updated_at": "2026-05-26T14:00:00"
    }
  ]
}

Get a single collection

GET https://user.openalex.org/collections/{collection_id}

Returns the same shape as one row in results above. The collection’s entities are paged separately to keep response sizes bounded:

GET https://user.openalex.org/collections/{collection_id}/entities?per_page=200

Returns the collection metadata plus the page of entity_ids (max per_page=200).

Update name, description, or entity type

PATCH https://user.openalex.org/me/collections/{collection_id}
Content-Type: application/json

{ "display_name": "Renamed", "description": "Updated notes" }

entity_type can be changed only while the collection is empty.

Delete a collection

DELETE https://user.openalex.org/me/collections/{collection_id}

Returns {"deleted_collection_id": "col_…"}. All collection_entities rows cascade-delete.

Add or remove entities

# Bulk add
POST https://user.openalex.org/me/collections/{collection_id}/entities
Content-Type: application/json

{ "entity_ids": ["W123…", "W456…"] }

Returns { "added": N, "already_present": M, "rejected_wrong_type": 0 }. Wrong-type IDs (e.g. an A… in a works collection) fast-fail with 400 naming the first offender, so rejected_wrong_type is always 0 on success — it’s preserved in the response shape for backward compatibility.

# Bulk remove
DELETE https://user.openalex.org/me/collections/{collection_id}/entities
Content-Type: application/json

{ "entity_ids": ["W123…"] }

# Single remove via URL
DELETE https://user.openalex.org/me/collections/{collection_id}/entities/W123…

Admin endpoints

OpenAlex admins can list, read, edit, or delete any user’s collection:

Method	Path	Notes
`GET`	`/admin/collections?q=&owner_id=&entity_type=`	Cross-user search, paged
`GET`	`/admin/collections/{collection_id}`	Read any collection
`PATCH`	`/admin/collections/{collection_id}`	Same body as the user PATCH
`DELETE`	`/admin/collections/{collection_id}`	Hard-delete with cascade

Non-admin callers get 403.

Validation rules

Collections are validated before they hit the database. The most common 400s:

Code	Cause
`entity_type_invalid`	`entity_type` missing or not one of the 10 supported types
`display_name_invalid`	Empty after trim, contains control characters, URL-shaped, or profane
`display_name_too_long`	More than 30 characters
`display_name_duplicate`	You already have a collection with this name (case-insensitive)
`description_invalid`	Not a string, or contains control characters, or URL-shaped
`entity_id_invalid`	An ID doesn’t look like any OpenAlex ID shape
`entity_id_wrong_type`	An ID’s type doesn’t match the collection’s `entity_type`
`collection_full`	Adding entities would exceed the 1,000-entity cap
`too_many_collections`	You already own 100 collections

Getting Started

Working with the API

Recipes

Curation

For AI Agents

Collections

Concepts

Creating a collection

Filtering search results by collection

Negation

Limits

Type matching

Negation

Limits

Managing collections

List your collections

Get a single collection

Update name, description, or entity type

Delete a collection

Add or remove entities

Admin endpoints

Validation rules

​Concepts

​Creating a collection

​Filtering search results by collection

​Negation

​Limits

​Filtering by a collection on a related entity

​Type matching

​Negation

​Limits

​Managing collections

​List your collections

​Get a single collection

​Update name, description, or entity type

​Delete a collection

​Add or remove entities

​Admin endpoints

​Validation rules

Concepts

Creating a collection

Filtering search results by collection

Negation

Limits

Filtering by a collection on a related entity

Type matching

Negation

Limits

Managing collections

List your collections

Get a single collection

Update name, description, or entity type

Delete a collection

Add or remove entities

Admin endpoints

Validation rules