> ## Documentation Index
> Fetch the complete documentation index at: https://developers.openalex.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Indexes Overview

> All bibliographic indexes in OpenAlex

Indexes are the bibliographic indexes and registries (like Crossref or PubMed) that list works. A work can be listed in several indexes at once.

## Values

| ID         | Display name |
| ---------- | ------------ |
| `crossref` | Crossref     |
| `datacite` | DataCite     |
| `arxiv`    | arXiv        |
| `doaj`     | DOAJ         |
| `pubmed`   | PubMed       |

Use these values with the `indexed_in` filter on works: `filter=indexed_in:doaj`

Like other entities, each index has its own record with live counts — for example, [`/indexes/doaj`](https://api.openalex.org/indexes/doaj) — and the full list is at [`/indexes`](https://api.openalex.org/indexes).