Image Credit: Pexels
Image Credit: Pexels

Researchers overwhelmingly rely on scholarly indexes to find vetted academic content online. So to develop and improve the reputation and discoverability of any journal, getting it added to trusted abstracting and indexing (A&I) databases is essential.

Most journal publishers and editors know this, but how to go about seeking inclusion in indexes isn’t always as clear.

Which indexes should you add your journal articles to? What are the indexing criteria you’ll need to fulfill? When should you apply for target indexes? In what order? And how can you keep improving your content discoverability once admitted to indexes?

In this blog post, we answer these common indexing questions and more, covering everything you need to know to initiate and keep building upon a successful journal indexing strategy. Feel free to use the section links below to skip ahead based on where you are in your indexing journey.

  1. Getting started: Understanding academic journal indexes
  2. Key journal index types to consider and the benefits of each
  3. How to develop an indexing strategy for one or more titles
  4. Key journal indexing criteria
  5. Navigating the journal indexing application process
  6. Tips for optimizing your article indexing outcomes
  7. Putting it all together

Getting started: Understanding academic journal indexes

Before we get into the nitty gritty of indexing, let’s start with some basics. What are journal indexes? Or, more specifically, how are we defining journal indexes for the purposes of this blog post?

Per this Walden University Library guide:

“An index is a list of items pulled together for a purpose. Journal indexes (also called bibliographic indexes or bibliographic databases) are lists of journals, organized by discipline, subject, or type of publication.”

Of course, mainstream search engines like Google and Bing also index content, but they do not fit the definition of an academic journal index. So we won’t get into them here.

However, with that said, many scholars use mainstream search engines in their research and want to know that their articles will be discoverable from them. So don’t forget to prioritize search engine optimization (SEO) with scholarly indexing. We cover everything you need to know about journal SEO for mainstream and academic search engines in this blog post.

Now, on to the primary types of academic journal indexes to consider (per the definition above).

Key journal index types to consider and the benefits of each

Before embarking on any journal indexing initiative, we recommend developing a target list of the indexes you’d like your journal or journals to be part of to get a bird’s-eye view of your ultimate goal. The more quality indexes you identify, the better, as inclusion in multiple indexes will help expand your articles’ reach and potential impacts while boosting the reputation of your journal(s).

From there, you can map out an indexing strategy based on your discovery goals and the specific criteria of the indexes you’re interested in (more on how to do this later). For example, Scopus requires journals to have a 2+ year publication history. So if you’re working with a new journal, you’ll logistically have to wait for at least two years before applying to that index, whereas; you’ll be able to seek inclusion in other indexes like Google Scholar sooner.

Below we outline the index types to consider and the benefits of each.

Scholarly search engines and aggregators

One of the best starting points for journal indexing is scholarly search engines and aggregators, many of which are freely available to researchers and the general public and often have less stringent inclusion criteria with regard to publication history, citation counts, and so forth.

The top academic search engine to focus on is Google Scholar, Google’s free crawler-based academic index. You can find our complete guide to Google Scholar indexing here. We also cover how to improve your chances of showing up higher in Google Scholar search results in our guide to journal SEO. You may have also heard of the Microsoft Academic search engine, but that was discontinued in December 2021.

Scholarly aggregator options with search functionality include Semantic Scholar, Dimensions, Lens, and CORE. Aggregators like these pull in content from other trusted academic databases, with the Crossref content registration agency being a prime source. So one of the best starting points for getting a new journal indexed is applying for Crossref membership and registering Digital Object Identifiers or DOIs for all the articles you publish. We cover how to apply for DOIs here and how to leverage the discovery benefits of Crossref in this webinar.

Registering DOIs for all articles is among the most common indexing application requirements, as discussed below. So it’s a good idea to apply for DOIs early on for new journals.

General scholarly archiving and indexing databases

In addition to getting indexed in scholarly search engines and aggregators, you’ll obviously want to seek inclusion in dedicated academic indexing databases, also known as abstracting and indexing databases or A&Is. You can apply to add your journal(s) to indexing databases that cover multiple disciplines as well as discipline-specific or “specialized” A&Is.

Many aggregators also ingest content directly from partner A&Is or require journals to be admitted to specific A&Is before being eligible to be included in their search results as a means of quality control, so applying to A&Is can help your articles appear in aggregator search results as well. For example, Semantic Scholar only indexes journals already in the Directory of Open Access Journals (DOAJ), and the National Institute of Health’s (NIH) free scholarly search engine PubMed pulls in all of its content from the NIH’s archiving and indexing databases MEDLINE and PubMed Central (PMC). So to be included in PubMed search, journals must be accepted to one of those databases first. You can learn more about the relationship between the NIH’s databases and how to apply to PMC and/or MEDLINE to be added to PubMed Search in this blog post.

There will be myriad indexing options for every journal, ranging from government and institutional indexes to commercial indexes run by publishers and data analytics companies. We obviously can’t cover every possible index in this blog post. But we’ve done our best to compile a list of some of the most widely-used and reputable general scholarly A&Is below (we cover top discipline-specific A&Is in the next section):

  • The Directory of Open Access Journals (DOAJ): The DOAJ is a non-profit community-curated online directory of peer-reviewed open-access journals. If you’re jumpstarting indexing for a new OA journal, we recommend beginning with the DOAJ because it’s a trusted OA index that various scholarly aggregators use as a data source. We compiled a complete guide to DOAJ indexing here. The DOAJ is a free-access index.
  • Ulrich’s Periodicals Directory: Ulrich’s is a leading library directory and database with information about academic journals and serial publications around the world that is part of Clarivate. Ulrich’s is a subscription-access index.
  • Scopus: Scopus is Elsevier’s abstract and citation database. It covers over 36,000 titles, spanning the life sciences, social sciences, physical sciences, and health sciences. You can read our guide to Scopus indexing here and a case study with the editors of Precision Nanomedicine, a Scholastica customer, about their experience getting indexed in Scopus here. Scopus is a subscription-access index.
  • Web of Science: WoS is Clarivate’s abstract and citation database. Its Core Collection encompasses six citation indexes in the sciences, social sciences, and humanities and collectively contains more than a billion searchable citations spanning over 250 disciplines. We compiled a complete guide to WoS indexing here. WoS is a subscription-access index.
  • EBSCO Information Services: EBSCO is a commercial index and aggregator that includes titles compiled by the company and journals from other databases, such as MEDLINE. EBSCO is a subscription-access index.
  • JSTOR: JSTOR is a digital library database that covers over 12 million journal articles, books, images, and primary sources in 75 disciplines. They are best known for hosting digitized content from journal back files, books, and other resources. They now publish journals willing to host articles solely on the JSTOR platform.
  • SciELO (Scientific Electronic Library Online): SciELO is a bibliographic database, digital library, and cooperative electronic publishing model for OA journals created to support the publication and increase the visibility of OA research in developing countries. SciELO is a free-access index.
  • Cabell’s: This last one is a little different. Rather than being an index readers use to find content, Cabell’s is a directory researchers use to determine which journals will be the best fit to publish in. Of course, attracting more high-quality submissions can also help journals expand their impact and reach, so it’s a good idea to pursue Cabell’s indexing. Cabell’s is a subscription-access index.

Discipline-specific or “specialized” indexes and search engines

Of course, the discipline-specific indexes you choose to apply to will depend on the subject area(s) your journals cover. If you’re unsure which indexes are the most widely used in a given journal’s discipline or across interdisciplinary areas, start to ask around. Query your authors, editors, reviewers, and readers to learn which discipline-specific databases they use.

There are many discipline-specific databases out there to look into. And some broader databases contain discipline-specific segments. For example, the Web of Science Core Collection includes the Science Citation Index Expanded, Social Sciences Citation Index, and Arts & Humanities Citation Index.

Other top discipline-specific or “specialized” indexes include the ones listed below.

STEM journals:

  • PubMed Central (PMC): PMC is a digital repository that archives OA full-text articles published in biomedical and life sciences journals. PMC is a free-access index with search functionality. PubMed aggregates articles from PMC. So Applying to PMC is the fastest way to be included in PubMed Search, as explained in this guide.
  • MEDLINE: This is the National Library of Medicine’s (NLM) bibliographic database of life sciences and biomedical research. MEDLINE is a free-access index searchable via PubMed.
  • PsycInfo: PsycInfo is the American Psychological Association’s abstracting and indexing database, with over three million records of peer-reviewed literature in the behavioral sciences and mental health fields. PsycInfo is a subscription-access index.
  • MathSciNet: MathSciNet is the American Mathematical Society’s searchable online bibliographic database containing over three million records of peer-reviewed literature. It is a subscription-access index.

Humanities and Social Sciences (HSS) journals:

  • Project MUSE: MUSE is an index of humanities and social sciences content, including journals, which only indexes content published by a not-for-profit press or scholarly society.
  • MLA Directory of Periodicals: This is a searchable list of publication information about the journals included in the MLA International Bibliography.
  • EconLit: The American Economic Association’s A&I focused on literature in the field of economics.

For more journal indexing options, check out Wikipedia’s list here and Nature’s list of indexes that their journals are part of here. The University of Miami Library also has a comprehensive list of indexes here.

Pro Tip: As a rule of thumb, if your journal is an OA publication, it’s a good idea to make getting added to the DOAJ a priority. The DOAJ is one of the top general indexing databases in terms of use and reputability that journals can usually apply for relatively early in their publication life. With over 12,000 journal members, over 1.2 million visitors a month, and a continually updating stream of journal metadata ingested by leading discovery services across disciplines, the DOAJ is a powerful platform for journal awareness.

How to develop an indexing strategy for one or more titles

Once you know the indexes you want to pursue, it’s time to map out your indexing strategy. Indexes will have varying levels of inclusion criteria (e.g., publication and technical standards journals must fulfill), so it’s a good idea to make a gradual indexing plan. Start with low-hanging fruit indexes that you can have your journal(s) added to early on, and then build up to more selective cross-discipline and discipline-specific/“specialized” scholarly databases such as Scopus and MEDLINE.

Of course, the more highly vetted an index is, the more trustworthy it will be to scholars. So journals should keep working to apply to more stringent databases as they mature and become eligible. Don’t just stop at a few!

When weighing your indexing options, consider the level of article discovery benefits different indexes will offer. For example, some databases only index article titles, abstracts, and/or references. Whereas some index entire article files. Generally, indexes that ingest more article details or the full text will be better for expanding content discoverability since they’ll have more information to go off of when deciding if and when to show your articles in search results. They also offer a more direct search experience for researchers.

As seen in the previous section, indexes also offer different levels of accessibility, with some being freely available to anyone interested in searching them, like Google Scholar and PubMed search, and others requiring a subscription, like Scopus and Web of Science. For open access (OA) journals especially, ensuring articles are easy to find via free online indexes, not just subscription databases, is paramount to maximizing content accessibility.

Pro Tip: When developing your indexing strategy, don’t forget to account for application review timelines. While some indexes review journals on a rolling basis, others only review applications at certain times throughout the year. So that will also factor into when you’ll be eligible for different indexes.

As you’re considering possible indexes to apply to, you’ll obviously want to start by visiting their application requirements pages and reading them thoroughly. Doing a quick Google search for “[index name] application criteria” or “how to get indexed in [index name]” will usually get you there. If you’re having trouble finding an index’s application criteria, you can also always visit their help/contact page to find a support email to write to for guidance.

Now, onto indexing application criteria journals should fulfill.

Key journal indexing criteria

As noted, reputable scholarly search engines, aggregators, and A&Is have admittance standards and often require journals to undergo an application process before being eligible for inclusion.

Here, we cover the most common indexing application criteria moving from basics to more stringent requirements. These are all publishing best practices, so you should aim to fulfill them regardless of which indexes you decide to pursue.

Publication standards

Starting with publication standards (e.g., journal details, editorial policies, etc.), in good news, many requirements will essentially be the same across scholarly indexes. Some of the most common publication criteria include that all journals should have:

  • An International Standard Serial Number (ISSN)
  • Digital Object Identifiers or DOIs for all articles (Crossref is the leading DOI registration agency for journals)
  • A dedicated editorial board page with the names, titles, and institutional affiliations of all editors
  • Clearly stated peer review policies, including an overview of the journal’s peer review process (e.g., type, stages of review) and statements on publication ethics
  • An established publishing schedule (e.g., bi-monthly, rolling)
  • An established copyright policy (e.g., CC BY for fully OA journals)

From there, indexes may have more specific additional guidelines. For example, some indexes require journals, particularly those that publish online only, to show that their articles are being added to an archive (this is also a general best practice!). Other specific indexing requirements may include guidelines around:

  • Publication scope: While many indexes accept journals in all disciplines or within a broad set of disciplinary areas, such as the humanities and social sciences, some only accept journals that publish within a particular subject area.
  • Minimum publication history: Some indexes require publishers and/or journals to be around for a minimum amount of time before applying. For example, MEDLINE only accepts applications from organizations that have published scholarly content for two years or more.
  • Level of publishing professionalization: Some indexes also look at the readability of published articles (e.g., level of editing) and production quality.
  • Geographic diversity: Some indexes look to see that journals have geographically diverse editorial boards and authors.
  • Adequate citations: Some indexes will not accept journals until they meet a certain citation-level threshold to demonstrate impact.

Technical requirements

In addition to publication standards like those outlined above, many scholarly search engines, aggregators, and indexes require or encourage journals to meet specific technical criteria for content ingestion.

First, it’s helpful to understand the three main ways scholarly search engines, aggregators, and A&Is ingest content:

  • Web crawlers: Some scholarly search engines like Google Scholar index journal articles via web crawlers or bots that systematically scan websites for content. For crawlers to be able to find and index articles, publishers must apply machine-readable metadata to all article pages via HTML meta tags and maintain a website structure that complies with the search engine’s requirements. For example, Google Scholar will only index articles hosted on their own webpage with HTML meta tags. You can learn more about Google Scholar’s technical inclusion criteria here.
  • Metadata/content deposits: Many indexes do not have web crawlers and instead require content deposits. In this case, publishers must submit article-level metadata and/or full-text article files to the index. Some indexes have forms for making manual metadata deposits. However, many require journals to directly deposit machine-readable metadata and/or full-text article files into the index via an FTP server or API integration. Making machine-readable metadata/article deposits is also a best practice because machine-readable metadata files are generally richer, more uniform, and less prone to inaccuracies than metadata input manually. JATS XML is the standard machine-readable format for journal metadata/article files. JATS, which was developed by the National Information Standards Organization (NISO), stands for Journal Article Tag Suite.
  • Cascading metadata: As noted above, some scholarly aggregators automatically ingest content from other trusted academic databases such as the Crossref content registration service and DOAJ index.

At a minimum, journals should aim to produce front-matter JATS XML article-level metadata files that include:

  • Journal publisher
  • Journal issue details (e.g., publication date and volume/issue number)
  • Journal title
  • ISSN
  • Article title
  • Author names
  • Keywords
  • Copyright license
  • Persistent Identifiers or PIDs (e.g., Digital Object Identifier, ORCID iD, ROR ID)

Once journals have the above core metadata fields, they can work to continue enriching their metadata outputs. We cover five elements of “richer” metadata to prioritize in this blog post.

Some databases also require full-text XML article files like PMC, which has specific JATS XML formatting guidelines.

We cover JATS XML 101 in this blog post and the what, why, and how of producing JATS XML in this webinar.

Producing XML in the JATS standard can get quite technical, but thankfully, there are software and services that can help. For example, Scholastica’s digital-first production service generates full-text JATS XML articles with rich metadata, and our fully-OA journal publishing platform features JATS XML metadata on all article pages.

From publication standards to technical requirements, most indexing criteria will be straightforward in nature. But fulfilling them will require a high level of attention to detail. That’s why, in all of your indexing endeavors, it’s so so so important to take your time!

Read indexing applications carefully, then re-read them again — we can’t emphasize this enough. And if you’re already in one index, don’t assume the criteria will be the same for the others. You’ll need to account for variables, big and small.

Also, if you have to update or add information to your journal website to fulfill indexing criteria, be sure to do so in all relevant places and to make required indexing information as specific and explicit as possible. For example, you don’t want your DOAJ application denied because you have missing or inconsistent copyright information on one of your website pages. (Yes, one page can make or break an application!).

Of course, it’s not the end of the world if an index denies your application! All indexes will allow you to reapply. But many require a waiting period for re-application (e.g., the DOAJ has a 6-month wait), so it pays to take some extra time to get your application right on the first round.

If you’re unsure whether one of your journals meets the criteria for a particular database, you can visit their website or contact their support staff to find out what you need to do to be eligible. Another great indexing resource is university libraries. Reach out to scholarly communication or subject-specific librarians to find out what they recommend. Many libraries are well-versed in helping journals get indexed.

Tips for optimizing your article indexing outcomes

A good indexing strategy extends beyond your initial application. Once admitted to indexes, adhering to the highest technical standards is critical to maximizing their discovery benefits.

Start by focusing on producing and enriching machine-readable article-level metadata to have more article details to send to indexes. That means including descriptive HTML meta tags on article website pages for crawler-based search engines and producing rich machine-readable metadata files for deposit-based A&Is. As noted, the machine-readable format standard for academic journals is JATS XML. JATS is preferred or required by many academic indexes, including all National Library of Medicine indexes (i.e., PubMed, PubMed Central, and MEDLINE).

For deposit-based indexes, it’s also important not to lose sight that content won’t be discoverable from those channels until it’s added. So the sooner you can make metadata/article file deposits for new or updated articles, the better. Ideally, you should automate index deposits where possible. Journal publishing platforms can help you here. For example, Scholastica’s OA publishing platform includes integrations with leading discovery services, including Crossref, the DOAJ, and PubMed.

Putting it all together

As you can see from this blog post, journal indexing is a process — and it will take time. But it’s well worth the effort to seek inclusion in various relevant indexes and to work to optimize your indexing outcomes. Adding journals to indexes helps expand their reach, reputation, and, consequently, their impacts.

We hope you’ve found this guide helpful! You can learn more about how Scholastica is helping journal publishers automate indexing steps here and how we’re helping journals produce machine-readable metadata to make articles more discoverable here.

Update note: This blog post was originally published on the 21st of June 2017 and updated on the 13th of April 2023.

Webinar Connecting Scholarly Metadata