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README.md

Work object

There's a lot of useful data inside a work. When you use the API to get a single work or lists of works, this is what's returned.

abstract_inverted_index

Object: The abstract of the work, as an inverted index, which encodes information about the abstract's words and their positions within the text. Like Microsoft Academic Graph, OpenAlex doesn't include plaintext abstracts due to legal constraints.

abstract_inverted_index: {
    Despite: [
        0
    ],
    growing: [
        1
    ],
    interest: [
        2
    ],
    in: [
        3,
        57,
        73,
        110,
        122
    ],
    Open: [
        4,
        201
    ],
    Access: [
        5
    ],
    ...
}

Abstract inverted index coverage

Newer works are more likely to have an abstract inverted index. For example, over 60% of works in 2022 have abstract data, compared to 45% for works older than 2000. Full chart is below:

alternate_host_venues (deprecated)

{% hint style="danger" %} The host_venue and alternate_host_venues properties have been deprecated in favor of primary_location and locations. The attributes host_venue and alternate_host_venues are no longer available in the Work object, and trying to access them in filters or group-bys will return an error. {% endhint %}

authorships

List: List of Authorship objects, each representing an author and their institution. Limited to the first 100 authors to maintain API performance.

authorships: [
    // first authorship object:
    {
        author_position: "middle",
        author: {
            id: "https://openalex.org/A5023888391",
            display_name: "Jason Priem",
            orcid: "https://orcid.org/0000-0001-6187-6610"
        },
        institutions: [
            {
                id: "https://openalex.org/I4200000001",
                display_name: "OurResearch",
                ror: "https://ror.org/02nr0ka47",
                country_code: "US",
                type: "nonprofit"
            }
        ]
    },
    
    // more authorship objects go here, omited for space.
]

apc_list

Object: Information about this work's APC (article processing charge). The object contains:

  • value: Integer
  • currency: String
  • provenance: String — the source of this data. Currently the only value is “doaj” (DOAJ)
  • value_usd: Integer — the APC converted into USD

This value is the APC list price–the price as listed by the journal’s publisher. That’s not always the price actually paid, because publishers may offer various discounts to authors. Unfortunately we don’t always know this discounted price, but when we do you can find it in apc_paid.

Currently our only source for this data is DOAJ, and so doaj is the only value for apc_list.provenance, but we’ll add other sources over time.

We currently don’t have information on the list price for hybrid journals (toll-access journals that also provide an open-access option), but we will add this at some point. We do have apc_paid information for hybrid OA works occasionally.

You can use this attribute to find works published in Diamond open access journals by looking at works where apc_list.value is zero. See open_access.oa_status for more info.

apc_payment: {
    value: 3200,
    currency: "USD",
    value_usd: 3200,
    provenance: "doaj"
}

apc_paid

Object: Information about the paid APC (article processing charge) for this work. The object contains:

  • value: Integer
  • currency: String
  • provenance: String — currently either openapc or doaj, but more will be added; see below for details.
  • value_usd: Integer — the APC converted into USD

You can find the listed APC price (when we know it) for a given work using apc_list. However, authors don’t always pay the listed price; often they get a discounted price from publishers. So it’s useful to know the APC actually paid by authors, as distinct from the list price. This is our effort to provide this.

Our best source for the actually paid price is the OpenAPC project. Where available, we use that data, and so apc_paid.provenance is openapc. Where OpenAPC data is unavailable (and unfortunately this is common) we make our best guess by assuming the author paid the APC list price, and apc_paid.provenance will be set to wherever we got the list price from.

apc_payment: {
    value: 2250,
    currency: "EUR",
    value_usd: 2426,
    provenance: "openapc"
}

best_oa_location

Object: A Location object with the best available open access location for this work.

We score open locations to determine which is best using these factors:

  1. Must have is_oa: true
  2. type_:_ "publisher" is better than "repository".
  3. version: "publishedVersion" is better than "acceptedVersion", which is better than "submittedVersion".
  4. pdf_url: A location with a direct PDF link is better than one without.
  5. repository rankings: Some major repositories like PubMed Central and arXiv are ranked above others.
best_oa_location: {
  is_oa: true,
  landing_page_url: "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1398957",
  pdf_url: null,
  source: {
    id: "https://openalex.org/S2764455111",
    display_name: "PubMed Central",
    issn_l: null,
    issn: null,
    host_organization: "https://openalex.org/I1299303238",
    type: "repository"
  },
  license: null,
  version: "publishedVersion"
}

biblio

Object: Old-timey bibliographic info for this work. This is mostly useful only in citation/reference contexts. These are all strings because sometimes you'll get fun values like "Spring" and "Inside cover."

  • volume (String)
  • issue (String)
  • first_page (String)
  • last_page (String)
biblio: {
    volume: "495",
    issue: "7442",
    first_page: "437",
    last_page: "440"
}

cited_by_api_url

String: A URL that uses the cites filter to display a list of works that cite this work. This is a way to expand cited_by_count into an actual list of works.

cited_by_count

Integer: The number of citations to this work. These are the times that other works have cited this work: Other works ➞ This work.

cited_by_count: 382

concepts

List: List of dehydrated Concept objects.

Each Concept object in the list also has one additional property:

  • score (Float): The strength of the connection between the work and this concept (higher is stronger). This number is produced by AWS Sagemaker, in the last layer of the machine learning model that assigns concepts.

Concepts with a score of at least 0.3 are assigned to the work. However, ancestors of an assigned concept are also added to the work, even if the ancestor scores are below 0.3.

{% hint style="info" %} Because ancestor concepts are assigned to works, you may see concepts in works with very low scores, even some zero scores. {% endhint %}

concepts: [
    {
        id: "https://openalex.org/C71924100",
        wikidata: "https://www.wikidata.org/wiki/Q11190",
        display_name: "Medicine",
        level: 0,
        score: 0.9187037
    },
    {
        id: "https://openalex.org/C3007834351",
        wikidata: "https://www.wikidata.org/wiki/Q82069695",
        display_name: "Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)",
        level: 5,
        score: 0.8070164
    },
    ...
    {
        id: "https://openalex.org/C191935318",
        wikidata: "https://www.wikidata.org/wiki/Q148",
        display_name: "China",
        level: 2,
        score: 0.5948172
    },
    ...
    {
        id: "https://openalex.org/C121608353",
        wikidata: "https://www.wikidata.org/wiki/Q12078",
        display_name: "Cancer",
        level: 2,
        score: 0.46887803
    },
    ...
    {
        id: "https://openalex.org/C17744445",
        wikidata: "https://www.wikidata.org/wiki/Q36442",
        display_name: "Political science",
        level: 0,
        score: 0
    }
]

corresponding_author_ids

List: OpenAlex IDs of any authors for which authorships.is_corresponding is true.

corresponding_author_ids: ["https://openalex.org/A5004365451"]

corresponding_institution_ids

List: OpenAlex IDs of any institutions found within an authorship for which authorships.is_corresponding is true.

corresponding_institution_ids: ["https://openalex.org/I4210123613"]

countries_distinct_count

Integer: Number of distinct country_codes among the authorships for this work.

countries_distinct_count: 4

counts_by_year

List: Works.cited_by_count for each of the last ten years, binned by year. To put it another way: each year, you can see how many times this work was cited.

Any citations older than ten years old aren't included. Years with zero citations have been removed so you will need to add those in if you need them.

counts_by_year: [
    {
        year: 2022,
        cited_by_count: 8
    },
    {
        year: 2021,
        cited_by_count: 252
    },
    ...
    {
        year: 2012,
        cited_by_count: 79
    }
]

created_date

String: The date this Work object was created in the OpenAlex dataset, expressed as an ISO 8601 date string.

created_date: "2017-08-08"

display_name

String: Exactly the same as Work.title. It's useful for Works to include a display_name property, since all the other entities have one.

display_name: "The state of OA: a large-scale analysis of the prevalence and impact of Open Access articles",

doi

String: The DOI for the work. This is the Canonical External ID for works.

Occasionally, a work has more than one DOI--for example, there might be one DOI for a preprint version hosted on bioRxiv, and another DOI for the published version. However, this field always has just one DOI, the DOI for the published work.

doi: "https://doi.org/10.7717/peerj.4375"

fulltext_origin

String: If a work's full text is searchable in OpenAlex (has_fulltext is true), this tells you how we got the text. This will be one of:

This attribute is only available for works with has_fulltext:true.

fulltext_origin: "pdf"

grants

List: List of grant objects, which include the Funder and the award ID, if available. Our grants data comes from Crossref, and is currently fairly limited.

grants: [
    // grant for which we have the grant details:
    {
        funder: "https://openalex.org/F4320306076",
        funder_display_name: "National Science Foundation",
        award_id: "ABI 1661218",
    },
    // grant for which we do not have the details:
    {
        funder: "https://openalex.org/F4320306084",
        funder_display_name: "U.S. Department of Energy",
        award_id: null,
    },
]

has_fulltext

Boolean: Set to true if the work's full text is searchable in OpenAlex. This does not necessarily mean that the full text is available to you, dear reader; rather, it means that we have indexed the full text and can use it to help power searches. If you are trying to find the full text for yourself, try looking in open_access.oa_url.

We get access to the full text in one of two ways: either using an open-access PDF, or using N-grams obtained from the Internet Archive. You can learn where a work's full text came from at fulltext_origin.

has_fulltext: true

host_venue (deprecated)

{% hint style="danger" %} The host_venue and alternate_host_venues properties have been deprecated in favor of primary_location and locations. The attributes host_venue and alternate_host_venues are no longer available in the Work object, and trying to access them in filters or group-bys will return an error. {% endhint %}

id

String: The OpenAlex ID for this work.

id: "https://openalex.org/W2741809807"

ids

Object: All the external identifiers that we know about for this work. IDs are expressed as URIs whenever possible. Possible ID types:

{% hint style="info" %} Most works are missing one or more ID types (either because we don't know the ID, or because it was never assigned). Keys for null IDs are not displayed. {% endhint %}

ids: {
    openalex: "https://openalex.org/W2741809807",
    doi: "https://doi.org/10.7717/peerj.4375",
    mag: 2741809807,
    pmid: "https://pubmed.ncbi.nlm.nih.gov/29456894"
}

institutions_distinct_count

Integer: Number of distinct institutions among the authorships for this work.

institutions_distinct_count: 4

is_paratext

Boolean: True if we think this work is paratext.

In our context, paratext is stuff that's in scholarly venue (like a journal) but is about the venue rather than a scholarly work properly speaking. Some examples and nonexamples:

  • yep it's paratext: front cover, back cover, table of contents, editorial board listing, issue information, masthead.
  • no, not paratext: research paper, dataset, letters to the editor, figures

Turns out there is a lot of paratext in registries like Crossref. That's not a bad thing... but we've found that it's good to have a way to filter it out.

We determine is_paratext algorithmically using title heuristics.

is_paratext: false

is_retracted

Boolean: True if we know this work has been retracted.

We identify works that have been retracted using the public Retraction Watch database, a public resource made possible by a partnership between Crossref and The Center for Scientific Integrity.

is_retracted: false

keywords

List of objects: Keywords extracted from the work's title, along with confidence scores from the extraction model.

We use a pretrained model to extract a list of keywords from the work's title. Not all works are assigned keywords. See the model documentation for more details.

[
    {
        keyword: "coastal marine ecosystems",
        score: 0.5626
    },
    {
        keyword: "kelp detritus",
        score: 0.5403
    },
    {
        keyword: "secondary production",
        score: 0.3469
    }
]

language

String: The language of the work in ISO 639-1 format. The language is automatically detected using the information we have about the work. We use the langdetect software library on the words in the work's abstract, or the title if we do not have the abstract. The source code for this procedure is here. Keep in mind that this method is not perfect, and that in some cases the language of the title or abstract could be different from the body of the work.

A few things to keep in mind about this:

  • We don't always assign a language if we do not have enough words available to accurately guess.
  • We report the language of the metadata, not the full text. For example, if a work is in French, but the title and abstract are in English, we report the language as English.
  • In some cases, abstracts are in two different languages. Unfortunately, when this happens, what we report will not be accurate.
language: "en"

license

String: The license applied to this work at this host. Most toll-access works don't have an explicit license (they're under "all rights reserved" copyright), so this field generally has content only if is_oa is true.

license: "cc-by"

locations

List: A list of Location objects describing all unique places where this work lives.

locations: [ 
  {
    is_oa: true,
    landing_page_url: "https://doi.org/10.1073/pnas.17.6.401",
    pdf_url: "http://www.pnas.org/content/17/6/401.full.pdf",
    source: {
      id: "https://openalex.org/S125754415",
      display_name: "Proceedings of the National Academy of Sciences of the United States of America",
      issn_l: "0027-8424",
      issn: ["1091-6490", "0027-8424"],
      host_organization: "https://openalex.org/P4310320052",
      type: "journal"
    },
    license: null,
    version: "publishedVersion"
  },
  {
    is_oa: true,
    landing_page_url: "https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1076072",
    pdf_url: null,
    source: {
      id: "https://openalex.org/S2764455111",
      display_name: "PubMed Central",
      issn_l: null,
      issn: null,
      host_organization: "https://openalex.org/I1299303238",
      type: "repository"
    },
    license: null,
    version: "publishedVersion"
  }
]

locations_count

Integer: Number of locations for this work.

locations_count: 3

mesh

List: List of MeSH tag objects. Only works found in PubMed have MeSH tags; for all other works, this is an empty list.

mesh: [
    {
        descriptor_ui: "D017712",
        descriptor_name: "Peer Review, Research",
        qualifier_ui: "Q000379",
        qualifier_name: "methods",
        is_major_topic: false
    },
    {
        descriptor_ui: "D017712",
        descriptor_name: "Peer Review, Research",
        qualifier_ui: "Q000592",
        qualifier_name: "standards",
        is_major_topic: true
    }
]

ngrams_url

{% hint style="info" %} ngrams_url is only displayed in the API and is not included in the OpenAlex snapshot. {% endhint %}

String: It lists groups of words and phrases (n-grams) that make up a work, as obtained from the Internet Archive. See The Ngram object and Get N-grams for background on n-grams, how we use them, and what this API call returns.

ngrams_url: "https://api.openalex.org/works/W2023271753/ngrams"

open_access

Object: Information about the access status of this work, as an OpenAccess object.

open_access: {
    is_oa: true,
    oa_status: "gold",
    oa_url: "https://peerj.com/articles/4375.pdf",
    any_repository_has_fulltext: true
},

primary_location

Object: A Location object with the primary location of this work.

The primary_location is where you can find the best (closest to the version of record) copy of this work. For a peer-reviewed journal article, this would be a full text published version, hosted by the publisher at the article's DOI URL.

primary_location: {
  is_oa: true,
  landing_page_url: "https://doi.org/10.1073/pnas.17.6.401",
  pdf_url: "http://www.pnas.org/content/17/6/401.full.pdf",
  source: {
    id: "https://openalex.org/S125754415",
    display_name: "Proceedings of the National Academy of Sciences of the United States of America",
    issn_l: "0027-8424",
    issn: ["1091-6490", "0027-8424"],
    host_organization: "https://openalex.org/P4310320052",
    type: "journal"
  },
  license: null,
  version: "publishedVersion"
}

publication_date

String: The day when this work was published, formatted as an ISO 8601 date.

Where different publication dates exist, we select the earliest available date of electronic publication.

This date applies to the version found at Work.url. The other versions, found in Work.locations, may have been published at different (earlier) dates.

publication_date: "2018-02-13"

publication_year

Integer: The year this work was published.

This year applies to the version found at Work.url. The other versions, found in Work.locations, may have been published in different (earlier) years.

publication_year: 2018

referenced_works

List: OpenAlex IDs for works that this work cites. These are citations that go from this work out to another work: This work ➞ Other works.

referenced_works: [
    "https://openalex.org/W2753353163",
    "https://openalex.org/W2785823074",
    "https://openalex.org/W2511661767",
    "https://openalex.org/W2115339903",
    "https://openalex.org/W2031754690"
]

related_works

List: OpenAlex IDs for works related to this work. Related works are computed algorithmically; the algorithm finds recent papers with the most concepts in common with the current paper.

related_works: [
    "https://openalex.org/W2753353163",
    "https://openalex.org/W2785823074",
    "https://openalex.org/W2511661767",
    "https://openalex.org/W2115339903",
    "https://openalex.org/W2031754690",
]

sustainable_development_goals

List: List of objects

The United Nations' 17 Sustainable Development Goals are a collection of goals at the heart of a global "shared blueprint for peace and prosperity for people and the planet." We use a machine learning model to tag works with their relevance to these goals based on our OpenAlex SDG Classifier, an mBERT machine learning model developed by the Aurora Universities Network. The score represents the model's predicted probability of the work's relevance for a particular goal.

We display all of the SDGs with a prediction score higher than 0.4.

sustainable_development_goals: [
    {
        id: "https://metadata.un.org/sdg/3",
        display_name: "Good health and well-being",
        score: 	0.95
    }
]

title

String: The title of this work.

This is exactly the same as Work.display_name. We include both attributes with the same information because we want all entities to have a display_name, but there's a longstanding tradition of calling this the "title," so we figured you'll be expecting works to have it as a property.

title: "The state of OA: a large-scale analysis of the prevalence and impact of Open Access articles",

type

String: The type of the work.

You can see all of the different types along with their counts in the OpenAlex API here: https://api.openalex.org/works?group_by=type.

Most works are type article. This includes what was formerly (and currently in type_crossref) labeled as journal-article, proceedings-article, and posted-content. We consider all of these to be article type works, and the distinctions between them to be more about where they are published or hosted:

(Note that distinguishing between journals and conferences is a hard problem, one we often get wrong. We are working on improving this, but we also point out that the two have a lot of overlap in terms of their roles as hosts of research publications.)

So, here is how you can filter for only non-preprint articles:

Works that represent stuff that is about the venue (such as a journal)—rather than a scholarly work properly speaking—have type paratext. These include things like front-covers, back-covers, tables of contents, and the journal itself (e.g., https://openalex.org/W4232230324).

We also have types for letter , editorial , and erratum (corrections). Coverage is low on these but will improve.

Other work types follow the Crossref "type" controlled vocabulary—see type_crossref.

type: "article"

type_crossref

String: Legacy type information, using Crossref's "type" controlled vocabulary.

These are the work types that we used to use, before switching to our current system (see type).

You can see all possible values of Crossref's "type" controlled vocabulary via the Crossref api here: https://api.crossref.org/types.

Where possible, we just pass along Crossref's type value for each work. When that's impossible (eg the work isn't in Crossref), we do our best to figure out the type ourselves.

type_crossref: "journal-article"

updated_date

String: The last time anything in this Work object changed, expressed as an ISO 8601 date string (in UTC). This date is updated for any change at all, including increases in various counts.

updated_date: "2022-01-02T00:22:35.180390"

The Ngram object

{% hint style="info" %} Ngram objects are only available in the API and are not included in the OpenAlex snapshot. {% endhint %}

ngram

String: Group of words (or numbers, letters, etc) that exist together in the work. This can be a five-gram, four-gram, trigram, bigram, or unigram.

ngram: "energy formula into a functional"

ngram_count

Integer: How many times this ngram occurred in the work.

ngram_count: 1

ngram_tokens

Integer: How many tokens are in the ngram.

ngram_tokens: 5

term_frequency

Float: How often the ngram occurred in the work.

Caution: This data was taken directly from the General Index and we've not tested term_frequency against actual articles. You can read about their data extraction process on the Internet Archive website. If you compare term_frequency against articles we would like to hear how it went!

term_frequency: 0.0005452562704471102

The OpenAccess object

The OpenAccess object describes access options for a given work. It's only found as part of the Work object.

any_repository_has_fulltext

Boolean: True if any of this work's locations has location.is_oa=true and location.source.type=repository.

Use case: researchers want to track Green OA, using a definition of "any repository hosts this." OpenAlex's definition (as used in oa_status) doesn't support this, because as soon as there's a publisher-hosted copy (bronze, hybrid, or gold), oa_status is set to that publisher-hosted status.

So there's a lot of repository-hosted content that the oa_status can't tell you about. Our State of OA paper calls this "shadowed Green." This feature makes it possible to track shadowed Green.

any_repository_has_fulltext: true

is_oa

Boolean: True if this work is Open Access (OA).

There are many ways to define OA. OpenAlex uses a broad definition: having a URL where you can read the fulltext of this work without needing to pay money or log in. You can use the locations and oa_status fields to narrow your results further, accommodating any definition of OA you like.

is_oa: true

oa_status

String: The Open Access (OA) status of this work. Possible values are:

  • gold: Published in an OA journal that is indexed by the DOAJ.
  • green: Toll-access on the publisher landing page, but there is a free copy in an OA repository.
  • hybrid: Free under an open license in a toll-access journal.
  • bronze: Free to read on the publisher landing page, but without any identifiable license.
  • closed: All other articles.
oa_status: "gold"

Diamond open access is another more recent designation that refers to works which are free for both readers and authors. In OpenAlex, there is no "diamond" oa_status, but diamond OA works can be identified using a combination of the is_oa and apc_list.value:

oa_url

String: The best Open Access (OA) URL for this work.

Although there are many ways to define OA, in this context an OA URL is one where you can read the fulltext of this work without needing to pay money or log in. The "best" such URL is the one closest to the version of record.

This URL might be a direct link to a PDF, or it might be to a landing page that links to the free PDF

oa_url: "https://peerj.com/articles/4375.pdf"