# Get Singleton

Use `GET /{entity_type}/{id}` to retrieve a single entity. The response is the full entity object.

```bash
curl "https://api.openalex.org/works/W2741809807"
```

**Cost:** Free

## OpenAlex IDs

Every entity has a unique OpenAlex ID with a letter prefix indicating the type:

| Prefix | Entity |
|--------|--------|
| W | Work |
| A | Author |
| S | Source |
| I | Institution |
| T | Topic |
| K | Keyword |
| P | Publisher |
| F | Funder |

You can use the full URL or just the key:

```bash
# Full URL
curl "https://api.openalex.org/works/https://openalex.org/W2741809807"

# Key only (recommended)
curl "https://api.openalex.org/works/W2741809807"
```

IDs are case-insensitive: `W2741809807` and `w2741809807` are equivalent.

## External ID lookups

You can look up entities using external identifiers. Pass the full external ID URL or use shorthand notation.

```bash
# DOI
curl "https://api.openalex.org/works/https://doi.org/10.7717/peerj.4375"

# ORCID
curl "https://api.openalex.org/authors/https://orcid.org/0000-0001-6187-6610"

# ROR
curl "https://api.openalex.org/institutions/https://ror.org/02y3ad647"

# ISSN
curl "https://api.openalex.org/sources/issn:0028-0836"

# PMID
curl "https://api.openalex.org/works/pmid:29456894"
```

### Short-form IDs

For convenience, you can use prefix notation instead of full URLs:

```bash
curl "https://api.openalex.org/works/doi:10.7717/peerj.4375"
curl "https://api.openalex.org/works/pmid:29456894"
```

### Canonical external IDs

Each entity type has a primary external identifier:

| Entity | Canonical ID |
|--------|--------------|
| Works | DOI |
| Authors | ORCID |
| Sources | ISSN-L |
| Institutions | ROR |
| Topics | Wikidata ID |
| Publishers | Wikidata ID |

## Merged entities

When duplicate entities are merged, requesting the old ID returns a `301` redirect to the new one:

```bash
$ curl -i https://api.openalex.org/authors/A5092938886
HTTP/1.1 301 MOVED PERMANENTLY
Location: https://api.openalex.org/authors/A5006060960
```

Most HTTP clients follow redirects automatically, so you will receive the merged entity's data without extra handling.