Provides access to metadata and full text of research articles gathered by CORE from various institutional repositories, subject repositories, open access journals and hybrid journals.
Requirements
API key is needed to use this API. Request for the API key here.
Return Format
The API returns result in JSON format.
Limitations
Useful Links
Provides access to metadata submitted by Crossref members such as bibliographic data, funding data, license information, full-text links, ORCID iDs, abstracts, and Crossmark updates.
Requirements
No API key or authentication needed, but Crossref encourages you to include your contact information on each call. As mentioned in the documentation (under "Etiquette" section), any API queries that use HTTPS and have appropriate contact information will be directed to a special pool of API machines that are reserved for polite users.
How to get added to the "polite users" pool:
You can do one of the following:
mailto parameter in your query. For example: https://api.crossref.org/works?filter=has-full-text:true&mailto=youremail@email.commailto in your User-Agent HTTP header. For example: GroovyBib/1.1 (https://example.org/GroovyBib/; mailto:GroovyBib@example.org) BasedOnFunkyLib/1.4Return Format
The API is generally RESTFUL and returns results in JSON.
Limitations
No request limit specified, but it's good to keep it within reasonable amount. From time to time, Crossref may impose a rate limit to ensure a good uptime. Check the status page to see if it's currently operational.
Useful links
API Wrappers
The DataCite REST API allows any user to retrieve, query and browse DataCite DOI metadata records.
Requirements
No API key or registration is required; the API is open for the public to use.
Return Format
The API return results in JSON format.
Limitations
No hard limits are imposed at the moment by DataCite.
Useful Links
Provides access to all the data in any of the OpenCitations datasets (the indexes and the corpus)
Requirements
The API is open to use for public, no API key required.
Return Format
The REST API returns result in JSON format or as a CSV document. This can be specified under the Accept HTTP header (see documentation for more details)
Limitations
No call limits are specified in documentation.
Useful Links
Provides on-demand source of data about authors, papers, citations, venues, and more from Semantic Scholar, a free, AI-powered academic search engine with nearly 200 million papers covering all disciplines.
Requirements
No API key is required.
Return Format
The API returns result in JSON format.
Limitations
The API allows up to 100 requests per 5 minutes. To access a higher rate limit, complete the form to request authentication for your project.
Useful Links
Provides access to the full corpus of Lens.org scholarly works (including patents). Bulk data download option is also available.
Requirements
You'll need to create an account in Lens.org to request access to the API and the bulk download option. The steps are outlined under the "How to Access APIs & Data" section. Once the request is approved, you are entitled to a 14-day free trial to explore the data and assess its suitability.
Return Format
The API returns result in JSON format
Limitations
5,000 API requests and up to 5 million records per month, 10 API requests/minute and up to 1,000 records per request. 60+ Searchable fields enhanced with filtering, paging and sorting. The API is not free but a 14-days trial is available.
Useful Links
Provides free, programmatic access to the Unpaywall.org database that contains open access contents from over 50,000 publishers and repositories.
Requirements
Requests must include your email as a parameter at the end of the URL, like this: api.unpaywall.org/my/request?email=YOUR_EMAIL
Return Format
The API return results in JSON format. The data schema is available here.
Limitations
Useful Links
OpenAlex is a free and open source “index of hundreds of millions of interconnected entities across the global research system”. It aggregates and standardize data from primarily Microsoft Academic Graph (MAG) and Crossref, as well as ORCID, Unpaywall, institutional repositories, etc. The API provides free access to OpenAlex data.
Requirements
To be included in the "polite pool" (much faster and more consistent response times), requests must include your email as a parameter at the end of the URL, like this: https://api.openalex.org/work?mailto=YOUR_EMAIL@example.com
Return Format
The API return results in JSON format. The data schema is available here.
Limitations
Useful Links