Did you know that you can request up to 50 DOIs in a single API call? That’s possible due to the OR query in the OpenAlex API and looks like this:

https://api.openalex.org/works?filter=doi:10.3322/caac.21660|https://doi.org/10.1136/bmj.n71|10.3322/caac.21654&mailto=support@openalex.org

We simply separate our DOIs with the pipe symbol ‘|’. That query will return three works associated with the three DOIs we entered. As you can see in the query, a short form DOI or long form DOI (as a URL) are both supported.

This will save time and resources when requesting many DOIs. This technique works with all IDs in OpenAlex, to include OpenAlex IDs and PubMed Central IDs (PMID).

Example with python requests

Let’s write an example python script to show how we can get DOIs in batches of 50 using requests:

import requests

dois = ["10.3322/caac.21660", "https://doi.org/10.1136/bmj.n71", "10.3322/caac.21654"]
pipe_separated_dois = "|".join(dois)
r = requests.get(f"https://api.openalex.org/works?filter=doi:{pipe_separated_dois}&per-page=50&mailto=support@openalex.org")
works = r.json()["results"]

for work in works:
  print(work["doi"], work["display_name"])

# results
https://doi.org/10.3322/caac.21660 Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries
https://doi.org/10.1136/bmj.n71 The PRISMA 2020 statement: an updated guideline for reporting systematic reviews
https://doi.org/10.3322/caac.21654 Cancer Statistics, 2021

Hope this is helpful!