APIs, short for application programming interface, are tools used to share content and data between software applications.
They are used in a variety of contexts, but some examples include:
Many databases, and products offer APIs to allow users with programming skills to more powerfully extract data to serve a variety of research purposes.
This page lists scholarly resources at The CEU Library that make their APIs available.
If you have programming skills and would like to use APIs in your research, use the information on this page to get started.
If you have any questions or know of an API you would like to see included in this list, please contact Ivett Molnar, molnariv@ceu.edu.
Thanks to MIT Libraries for some content and inspiration.
| API | What it does | How it is accessed | Results format | Registration and contact for technical questions |
Limitations |
|---|---|---|---|---|---|
| arXiv API | Gives programmatic access to all of the arXiv data, search and linking facilities | API calls are made using any web-enabled client (e.g. a web browser) to make an HTTP GET or POST request to an appropriate url. API users can use the programming language of their choice. | Atom |
Free to use, no registration or API key required. |
No stated limitations, but high-volume users should contact arXiv at http://arxiv.org/help/contac |
| BioMed Central API | Retrieves: 1) BMC Latest Articles; 2) BMC Editors picks; 3) Data on article subscription and access; 4) Bibliographic search data | RESTful interface, queries are made as HTTP GET requests | JSON |
Free to access, no registration required. |
No limitations at present. |
| CrossRef REST API | Allows access to metadata records for over 75 million scholarly works that have CrossRef DOIs, covering around 5000 publishers. Can be used for text- and data-mining, checking against funder mandates, and to obtain metadata in a variety of representations. | RESTful interface | JSON |
No registration required. |
No limitations at present. |
| DVN (Dataverse Network) API for Data Sharing | Allows programmatic access to data and metadata in the Dataverse Network. Two modules exist: Metadata/Search and Data Access | HTTPS. A Dataverse community-written software program can also be used to access the API via an RCurl package. | XML; Byte Stream for Data Access requests | Metada access does not require registration. Data set downloads require a user account and agreement to terms of use; users interested in data sets should contact DVN support. Access to restricted data sets requires approval by data owners.
dvn_support@ Questions can |
No limitations on public data set downloads after agreeing to terms of use. No limitations on restricted data set downloads after access is granted by data owners. |
| Digital Public Library of America (DPLA) API | Allows programmatic access to metadata in DPLA collections, including partner data from Harvard, New York Public Library, ARTstor, and others. | RESTful interface | Structured JSON-LD objects | Free to use; API key needed.
|
No limitations at present |
| HathiTrust Bibliographic API | Returns bibliographic, rights, and volume information when given standard identifiers (ISBN, LCCN, OCLC, etc.) for items in the HathiTrust Digital Library. Intended for use to retrieve information about small numbers of items at a time. | RESTful interface | JSON, MARC-XML | No registration required. feedback@issues.hathitrust.org |
No stated limitations but intended for use to retrieve information about small numbers of items at a time. |
| HathiTrust Data API | Can be used to retrieve content (page images, OCR, and in some cases whole volume packages), and metadata for HathiTrust Digital Library volumes. | Two methods of access: via a Web client, requiring authentication (users who are not members of a HathiTrust partner institution must sign up for a University of Michigan "Friend" Account), or programmatically using an access key. Request access key. | XML, JSON, or binary representation | Varies depending whether access is via Web client (for members of HathiTrust partner institution), University of Michigan "Friend" Account, (for non-members), or using API key. Request API key. feedback@issues.hathitrust.org |
No stated limitations but is not meant for large-scale retrieval of data. |
| JSTOR Data for Research | Not a true API, but allows computational analysis and selection of JSTOR's scholarly journal and primary resource collections Includes tools for faceted searching and filtering, text analysis, topic modeling, data extraction, and visualization. | Web interface | CSV, varies depending on tool used | Free to access, registration is required to obtain results. No institutional affiliation is required. Contact JSTOR |
Datasets are capped by default at 1,000 articles; users seeking larger results are asked to contact JSTOR Data for Research. |
| Nature Blogs API | Blog tracking and indexing service; tracks Nature blogs and other third-party science blogs | RESTful interface, queries are made as HTTP GET requests | Default is JSON, some queries return Atom/RSS, CSV | Free to register, developer account and API key needed. developers@nature.com |
2 calls per second; 5,000 calls per day; RSS results are limited to 100 items maximum |
| Nature OpenSearch API | Bibliographic search service for Nature content | REST API with two interfaces: 1) OpenSearch standard interface using keyword searches; 2) SRU search interface using CQL structed queries | RSS, JSON, ATOM, SRU XML, TURTLE, depending on interface used | Free to register, developer account and API key needed. developers@nature.com |
2 calls per second; 5,000 calls per day |
| NLM APIs | NLM offers 21 different APIs for accessing various NLM databases. | Varies depending on API. | Varies depending on API. | Varies depending on API. | Varies depending on API. |
| OECD Data API | Allows programmatic access to a selection of OECD datasets | A dataset identifier, a list of dimension item identifiers, and some additional parameters need to be supplied in a URL | SDMX-JSON | Free to register. Registration is not required but is strongly encouraged. FAQ & Contact |
1 million data points; not all OECD datasets are covered; IEA datasets are excluded |
| ORCID API | Queries and searches the ORCID researcher identifier system and obtain researcher profile data | RESTful interface | HTML, XML, or JSON | Two options: 1) Users can access the Public API,which only returns data marked as "public"; 2) Become an Orcid member to receive API credentials. | Data retrieved through Public API is limited |
| PLoS Article-Level Metrics API | Retrieves article-level metrics (including usage statistics, citation counts, and social networking activity) for articles published in PLOS journals and articles added to PLOS Hubs: Biodiversity | RESTful interface, queries are made as HTTP GET requests | XML, JSON, CS | Free to register. API key needed. Go to http://api.plos.org/registration/. api@plos.org; Questions can also be posted in PLoS API Google Group |
Max is 1000 requests a day. Users should wait 5 seconds for each query to return results. High-volume users should contact api@plos.org. API users are limited to no more than five concurrent connections from a single IP address |
| PLoS Search API | Allows PLoS content to be queried using the 23 terms in the PLoS search, for integration into web, desktop, or mobile applications | RESTful interface, queries are made as HTTP GET requests | XML | Free to register. API key needed. Go to http://api.plos.org/registration/. api@plos.org; Questions can also be posted in PLoS API Google Group |
Max is 7200 requests a day, 300 per hour, 10 per minute. Users should wait 5 seconds for each query to return results. Requests should not return more than 100 rows. High-volume users should contact api@plos.org. API users are limited to no more than five concurrent connections from a single IP address. |
| PubMed E-Utilities API | Set of 8 server-side programs for searching 38 NCBI Entrez databases of biomedical literature and data | To access data, a piece of software posts an URL using a fixed sytax to NCBI's E-Utilities server, then retrieves and processes data. Users can use any programming langauge that can send the URL and interpret the XML response (e.g. Perl, Python, Java, C++, etc.) | XML | Free to register; registration is not necessary but strongly encouraged. eutilities@ncbi.nlm.nih.gov |
3 URL requests per second; large jobs should be limited to weekends or business hours |
| ScienceDirect | Supports multiple use cases, including text mining of full-text content, search widgets, displaying journal or book level data, federated searching, and indexing. | Various depending on use case. | Varies depending on use case. | Free to register. |
Varies depending on use case. |
| Scopus | Supports multiple use cases, including displaying publications on a website, showing cited-by counts on a website, federated searching, populating repositories with metadata, populating VIVO profiles, and others. | Various depending on use case. | Various depending on use case. | Free to register. |
Varies depending on use case. |
| Springer Text- and Data-Mining Access | Allows text- and data- mining access to researchers via their subscribing institutions for non-commercial research purposes. | Researchers can download content for TDM purposes directly from the SpringerLink platform. Full-text content can be accessed programmatically at friendly URLs based on the content’s DOI. Can use a web browser, or HTTP GET requests using any convenient scripting tool, e.g. curl, wget, Python’s urllib, among others. | Varies depending on use case. | No registration or API key is required. mikail.shaikh@springer.com |
No stated limitations but TDM researchers are asked to be considerate and limit their downloading speed to a reasonable rate. |
| Springer Images API | Provides images and related text for over 300,000 free images available on Springer Images. | RESTful interface, using structured URL requests | XML, JSON, JSONP | Free to register. API key needed. support.api@springer.com |
No stated limitations. High-volume users should contact Springer. |
| Springer Metadata API | Provides metadata for over 5 million online documents (e.g. journal articles, book chapters, protocols). | RESTful interface, using structured URL requests | XML in PRISM Aggregator message format, JSON, JSONP | Free to register. API key needed. support.api@springer.com |
No stated limitations. High-volume users should contact Springer. |
| Springer Open Access API | Provides metadata, full-text content, and images for over 80,000 open access articles from BioMed Central and SpringerOpen journals. | RESTful interface, using structured URL requests | XML in Springer's A++ format, JSON | Free to register. API key needed. support.api@springer.com |
No stated limitations. High-volume users should contact Springer. |
| STAT!Ref OpenSearch API | Bibliographic search service for displaying syndicated results on a website. | Uses OpenSearch specifications. | RSS, ATOM, HTML | Free to register for users at subscribing host institution. support@tetondata.org |
Limits exist but are not specified; high-volume users should contact STAT!Ref. |