Search strategy

To map the availability of mental health–related apps, we conducted a systematic search of the iOS (Apple Store) and Android (Google Play) platforms, reporting results using the PRISMA guidelines. Similar methodologies have been used in prior studies. [21,22]. Apps were searched in the Apple App Store and Google Play Store between April 28 and May 5, 2025. We developed a list of predefined self-help-related keywords informed by prior literature [5,12,23]. After discussion within the research team, four final keywords were selected (“mental health,” “psychological wellbeing,” “self-help,” and “stress”) to reflect search terms that young people are most likely to use when seeking digital mental health support.

Searches were conducted by authors with expertise in digital mental health and youth mental health across seven countries: Croatia, France, Ireland, Poland, Portugal, Serbia, and Türkiye.This study focuses on seven European countries (Croatia, France, Ireland, Poland, Portugal, Serbia, and Türkiye) selected through purposive sampling to capture heterogeneity rather than to provide exhaustive coverage of all European countries. The countries were chosen to reflect diversity in geographic regions (Western, Southern, and Central/Eastern Europe), political and health system contexts, and linguistic and cultural environments. We also prioritised countries where the research team had sufficient linguistic and contextual expertise to systematically search, screen, and interpret app content in the local language(s). Consequently, the seven countries should be understood as an illustrative sample of European contexts, rather than a representative selection of all European countries.

In Ireland, searches were performed only in English, the primary language of the app store. In the remaining countries, two parallel searches were conducted: one using English keywords and another employing translations into the respective national language. Conducting searches in both languages enabled the identification of apps that may be marketed differently across linguistic contexts, thereby reducing the risk of missing relevant, locally targeted apps.

Each researcher conducted searches via their respective national app-store settings. To minimise algorithmic bias, personalized recommendations and search history features were disabled prior to data collection. This approach reflected realistic user conditions while limiting the potential influence of prior browsing activity on search results. To ensure comparability and to capture the apps most likely to be encountered by users, only the first ten results returned for each search were included. This threshold likely reflects the real-life behaviour of young people [12,24,25]. The full output of the initial searches is available in S1 Table.

In this study, “young people” was defined as individuals aged 11–25. This age range captures the key developmental transitions from childhood to adolescence and from adolescence to early adulthood, during which the majority of mental health difficulties emerge: 75% of mental health conditions have their onsent before the age of 25 [26]. It is important to note that app store classifications do not typically align with this definition. Instead, apps are categorised using broad age ratings (e.g., 4 + , 12 + , 18+), which do not necessarily reflect developmental appropriateness or suitability for youth mental health support. Therefore, age-related classifications reported in this study reflect app store metadata rather than verified target populations. Importantly, this study did not assume that apps categorised as “4+” or “12+” were specifically designed for children or adolescents. Rather, these classifications were used to examine which apps are broadly accessible and visible to young people within commercial app stores. Where app descriptions explicitly identified a target population (e.g., young adults, or families), this information was extracted separately.

Data extraction procedure

For each keyword, datasets were generated, including app results from all seven countries. A structured codebook was developed to guide the systematic extraction of data from each app. The following information was coded: app name, primary aim, key features, app store, cost model, age rating, date of last update, user rating, number of downloads, and any declared implementation of AI.

As shown in the PRISMA flowchart (Fig 1), a total of 967 apps were identified across all keywords and countries during the app store searches (460 apps from Apple App Store, and 507 apps from the Google Play Store). After removing 661 duplicate entries, 306 unique apps were retained and screened. Predefined exclusion and inclusion criteria were applied for screening the apps (see Table 1). Apps with the most recent update dating back more than six months (i.e., before September 2024) were excluded to avoid including apps that were no longer actively used and/or regularly reviewed and updated. Additional apps were excluded if their primary focus was unrelated to mental health or psychological wellbeing, or if they targeted only physical health conditions. Following this screening process, 171 apps met all criteria and were retained for final analysis.

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Table 1. Inclusion and exclusion criteria used to identify eligible mental health-related applications from the app stores.

https://doi.org/10.1371/journal.pdig.0001622.t001

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Fig 1. PRISMA flow diagram of apps included within the search.

https://doi.org/10.1371/journal.pdig.0001622.g001

All included apps were compiled into a single spreadsheet for subsequent categorization and analysis. Based on information provided in the app store descriptions, each app was characterized according to its purpose, target population, cost structure, language availability, and declared AI integration. It should be noted that only the Apple App Store, and not the Google Play Store, explicitly lists supported languages.

Cross-country app visibility

The review of the 171 apps revealed several similarities in the visibility of apps across countries and search terms. In particular, English-language and commercial apps were dominant. The same high-visibility commercial English-language applications frequently appeared in the search results across the seven countries, including Headspace, Wysa, MindDoc, VOS (a mood and wellbeing tracking app) and Daylio. This overlap indicates a strong global market presence for English-language commercial mental health apps. In addition, searches conducted in non-English languages (Croatian, French, Polish, Portuguese, Serbian and Turkish) largely returned English-language apps, with relatively few locally developed or language-specific options available. In several cases, particularly for Serbian and Croatian searches, specific keywords, such as “self-help” or “psychological wellbeing,” returned very few or no results.

Cross-country discrepancies were also observed in app store metadata. These differences suggest that app visibility and user engagement metrics may vary across national app store contexts, even for globally dominant applications, showing that even the same app is presented differently to users depending on which country’s store they access. For example, Headspace, the most globally visible app in our sample, showed notable variation in user ratings and review counts across country-specific Apple Store listings (Table 2), indicating that app “popularity” as indexed by ratings is not directly comparable across national contexts.

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Table 2. Example of country-specific variation in Apple App Store data for Headspace.

https://doi.org/10.1371/journal.pdig.0001622.t002

Cross-language and cross-country differences

Cross-country differences were most evident in the contrast between English-language and native-language searches. English-language searches consistently returned a broader range of commercially dominant apps across all countries, including Headspace, Wysa, Daylio, MindDoc, and BetterMe. In contrast, searches conducted in local languages frequently yielded fewer results, particularly in Croatia and Serbia, where some translated keywords returned minimal or no relevant applications. For example, Serbian-language searches using terms related to “psychological wellbeing” returned no Apple App Store results for several keywords, whereas Croatian-language searches often returned only a small number of locally relevant applications.

Differences were also observed between countries in the extent of localisation and cultural adaptation. French- and Portuguese-language searches generally returned a broader range of locally adapted or partially localised apps, including apps available in French or Portuguese interfaces, whereas searches conducted in Serbian, Croatian, and Turkish more commonly returned English-language commercial apps with limited localisation beyond translation of the app title or description.

Native-language searches were also more likely to return apps focused on general stress reduction, self-help, or wellbeing rather than apps describing therapeutic or clinically oriented support. Across countries, relatively few apps appeared to be specifically tailored to local cultural or linguistic contexts. Most apps identified through local-language searches were either direct translations of English-language commercial apps or applications with limited localisation beyond interface language.

Overall, these findings suggest that young people searching in English may encounter a broader and more diverse range of digital mental health resources than users relying solely on native-language search terms. A country-level comparison of English-language versus local-language app search outputs is presented in S2 Table.

App categories and core characteristics

Based on the information available on the app descriptions provided in the app stores, the 171 included apps were classified into five main categories. A total of 12% (20/171) of apps were classified as content-focused, providing content on mental health with no interactive elements; 50% (85/171) of apps primarily offered self-guided tools like journaling, meditations, and breathing exercises; 16% (28/171) of apps primarily offered an AI-chatbot; 13% (22/171) were gamified apps; and 9% (16/171) of apps provided access to online therapists. An overview of the characteristics of the different app categories is presented in Table 3, and a detailed description of the included apps is provided in S3 Table. It is important to note that across all 171 included apps, only a small subset explicitly named young people as their primary intended audience in the app store description. Apps that explicitly targeted young people included Lyynk (described as designed to help young people better understand themselves, alongside resources for trusted adults), WeCare: Santé mentale (designed for young people aged 18–25 years), and one structured journaling and meditation app specifically designed for young adults and their trusted adults. The vast majority of apps did not specify any youth-focused design intent, which is itself a notable finding given this study’s focus on young people’s digital mental health access. App store age ratings (4+, 12+, 17+/18+) reflect content thresholds applied by platform operators rather than developer-stated target populations, and should not be interpreted as indicators of youth-appropriate design.

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Table 3. Characteristics of included apps per category.

https://doi.org/10.1371/journal.pdig.0001622.t003

Principal findings

Mental-health-related smartphone applications have become increasingly prevalent, and prior research has evaluated such apps in various countries, including China [27,28], India [29], and France [22]. Previous reviews have also examined the mental-health app landscape across multiple countries within a single analysis [23]. However, to our knowledge, this is the first review to synthesize the full range of available and widely used mental health-related applications that young people might frequently encounter across seven European countries: Croatia, France, Ireland, Poland, Portugal, Serbia, and Türkiye. Accordingly, this review aimed to identify cross-country differences and analyze the content of these applications using available app store data, with a particular focus on store descriptions.

The findings suggest that language plays a critical role in shaping the visibility and presentation of mental health-related applications across countries and app stores. Importantly, the language used to conduct searches directly influenced which apps were returned, with English-language searches consistently yielding a broader range of popular commercialised applications, such as Headspace, BetterMe, and Daylio, than local language searches. This pattern underscores the global dominance of English-language apps and suggests limited localisation or cultural adaptation. Although application popularity is often inferred from user ratings, these ratings are inherently biased, reflecting the experiences of particular user groups rather than the clinical effectiveness of the applications [30]. Substantial empirical evidence supports the efficacy of Headspace in promoting psychological wellbeing [23,30–33], which may partly account for its strong market presence and visibility. However, given that the studies cited were published after the launch of Headspace (2022–2024 vs. 2012, respectively), it could be argued that its early market dominance may have, in fact, simulated subsequent empirical research on its effectiveness. In contrast, the majority of other top-ranked applications lack empirical validation, including evidence from randomized controlled trials, which raises concerns about the potential risks associated with unregulated or non-evidence-based mental health-related apps, particularly for young people seeking help. This issue has been widely discussed in the literature [4,5,34].

In contrast, searches conducted in the native language often returned fewer results or more localized results, some of which were irrelevant to the study’s objectives. For example, Turkish search terms, such as “psikolojik iyi oluş” (psychological wellbeing), produced fewer results overall than equivalent English terms across both app stores. This might suggest that clinical terminology is less commonly used in local app descriptions, which limits the visibility of such apps in native-language searches. Moreover, cross-country differences were observed in app store data, particularly in ratings and download counts, highlighting inconsistencies in how mental health apps are presented in the same app stores depending on the geolocation of the search. This further accentuates differences across linguistic and regional contexts, as shown in the results section. Collectively, these findings suggest that young people searching in their native languages may encounter a narrower and more commercialized selection of apps, compared to the broader and more clinically diverse range available through English-language searches, potentially representing an accessibility barrier for non-English-speaking youth. This is especially important since expressing mental health concerns is easier in one’s native language than a foreign language [35].

During the app selection process, the primary reason for exclusion was that most applications had not been updated within the six months before data collection. This may indicate that apps remaining outdated for extended periods tend to be of lower quality, particularly in terms of privacy protections, feature relevance, and evidence base [36]. Additionally, low user retention reduces developers’ incentives to maintain or update their applications. Mental health applications are characterized by particularly low engagement rates; for example, a study of 93 mental health apps reported a median 15-day retention rate of 3.9% and a 30-day retention rate of 3.3%, suggesting that most users discontinue use within the first two weeks [37]. As user activity declines, developers may see little reason to continue releasing regular updates. Consequently, many apps become effectively “finished” from the publisher’s perspective, remaining available without active development. This reflects a broader “build fast, move on” model within the digital marketplace, in which developers prioritise rapid release and short-term user growth over sustained maintenance or evidence-based refinement [38].

Our review also found that meditation and journaling applications constitute the majority of currently available mental health-related apps in the app stores. Searches for mindfulness-based applications have increased significantly in recent years, reflecting their dominance in the digital mental health marketplace [3,38]. Moreover, mindfulness applications have demonstrated effectiveness in reducing symptoms of anxiety and depression and enhancing psychological wellbeing [39], which may help explain their widespread popularity and visibility. These findings suggest that the visibility of mental health apps is associated not only with linguistic accessibility but also with applications’ content focus, with mindfulness and journaling apps more likely to surface in app store searches. However, most of these applications are oriented toward general mental wellbeing rather than evidence-based therapeutic care [40], which may limit their suitability for young people seeking more clinically guided support.

A more detailed analysis revealed that the majority of the mental health-related apps were not entirely free to use. Most offered a freemium model, offering a basic version at no cost alongside premium features through subscription or one-time payment. This model allows young people to explore a wide range of mental health tools without financial barriers, use these apps as an adjunct to ongoing therapy, or as an alternative for those who prefer self-management of symptoms [40]. Notably, although most apps connecting users to online therapists were technically free to download, this did not necessarily imply free access to therapy itself. In many cases, app descriptions indicated that consultations, subscriptions, employer-based healthcare access, or session fees were required to access professional services. Therefore, “free download” classifications should not be interpreted as equivalent to free mental health care access.

However, freemium models also restrict access to key features or evidence-based modules, potentially pressuring vulnerable youth to download unhelpful or costly apps and undermining both effectiveness and user trust [41]. These accessibility dynamics may further explain why meditation and journaling applications dominate the marketplace, as their free content enables engagement with mental health support even when premium features remain inaccessible.

Taken together, the patterns identified in this review reflect not just individual app characteristics but systemic features of the digital mental health ecosystem that have direct implications for governance, equity, and implementation. The concentration of visible apps in English, combined with limited localisation, points to a structural gap in how digital health tools are developed and regulated: market incentives favour scale and English-speaking audiences over cultural or linguistic appropriateness. For instance, Muñoz, Camacho, and Torous [42] found that only 14.5% of mental health apps on the commercial marketplace were operable in Spanish, despite Spanish being the fourth most spoken language globally, a disparity that can reasonably be extrapolated with far fewer speakers. Additionally, Whitehead et al. [43] highlighted language and culture as potential barriers to the accessibility of digital health interventions. From a governance perspective, this underscores the absence of coordinated regulatory frameworks that could ensure equitable app visibility and quality across national app stores.

Current app store curation relies largely on commercial marketplace dynamics rather than clinical or public health criteria; app visibility is driven by popularity metrics such as downloads and ratings, which have been shown not to correlate with evidence-based quality or privacy standards [44], meaning that the apps most visible to young people in any given country are shaped more by commercial success than by evidence of effectiveness or cultural fit. Furthermore, the prevalence of freemium cost models introduces tiered access structure within digital mental health ecosystems, where key features are often restricted behind paywalls, raising concerns about equitable access to effective support [3]. This has implications for equity, particularly for young people who may rely on free resources. In the absence of standardized regulatory frameworks or certification systems across countries, users and healthcare systems are left to navigate a highly heterogeneous and largely unregulated marketplace. These findings underscore the need for coordinated policy efforts at national and international levels to ensure that digital mental health interventions are accessible, evidence-based, and culturally appropriate, particularly for youth populations.

Limitations and directions for future research

While the current study reveals important cross-country similarities and discrepancies in the availability of mental health smartphone apps, the findings should be interpreted in light of its limitations. First, relevant apps may have been missed in the identification process. App identification relied on the algorithms of the Apple App Store and Google Play Store, which vary according to geolocation and language, potentially affecting app capture and ranking. The search strategy captured only the first 10 results per keyword in seven European countries, using English and local languages. Although this approach reflects real-world behaviour, it may not fully represent the apps most commonly used by young people. Moreover, some app store entries lacked key information, such as downloads or supported languages, and inconsistencies in app naming may have led to relevant apps being missed.

The analysis was based on publicly available descriptions rather than direct testing of the apps. As such, app functionality, gamified features, AI integration, or therapist credentials could not be verified. Additionally, while this study examined which apps were accessible and visible to young people within commercial app stores, it did not include a qualitative assessment of app interface design, developmental appropriateness, readability, visual presentation, or intervention suitability for youth populations. As such, the findings should not be interpreted as evidence that apps categorised as “4+” or “12+” were specifically designed for or appropriate for children or adolescents. Future research should incorporate direct app testing and qualitative evaluation methods to assess the extent to which digital mental health applications are genuinely youth-centred in their design, content, and therapeutic approach.

Likewise, apps were categorised by thematic group and described by cost, target population, and language availability; however, no formal quality assessment [e.g., the Mobile App Rating Scale, [45]] was conducted. To gain a better understanding of which mental health applications young people use, how they discover them, and which features they perceive as most beneficial or insufficient, future research should actively engage young people from diverse cultural and national contexts.

Relatedly, while the current study compares app features, it does not examine user responses, such as number of downloads or user ratings. Although user ratings and download indicators were extracted during data collection, they were not systematically analysed as comparative variables in this study. User ratings reflect subjective experiences of self-selected users and may vary across country-specific app store listings, limiting their reliability for cross-country comparison. Furthermore, download data are not consistently reported across platforms: the Apple App Store does not provide download counts, while the Google Play Store reports downloads in broad ranges rather than exact figures. Download data also does not reflect actual usage of the apps. As such, these metrics were not suitable for robust comparative analysis. Future research could build on this work by incorporating more precise and standardised measures of user engagement and adoption to better understand the real-world reach and impact of digital mental health applications.

A further limitation concerns the geographic scope of the present analysis. The seven countries were selected through purposive sampling to capture heterogeneity across European geographic regions, political, and health system contexts, and linguistic environments, rather than as a representative sample of all European contexts. As such, the findings should be interpreted as illustrative of cross-country patterns in digital mental health app visibility rather than generalised to Europe as a whole. Furthermore, the sample does not include non-European English-language markets such as the United States, which represents one of the largest and most commercially dominant markets for digital mental health applications [19]. Extending this comparative framework to North American or other non-European app store contexts is an important direction for future research. Additionally, the present analysis relied exclusively on app store descriptions and metadata, which do not incorporate population-level variables such as economic status or age structure. The countries included in this study span settings with varying economic and demographic profiles. A more systematic integration of socioeconomic and demographic data would substantially strengthen the interpretive power of cross-country comparisons and is an important direction for future research. App developer country of origin was not systematically extracted because this information was inconsistently available across app store platforms and developer profiles. Consequently, the present study was unable to assess whether apps were developed locally or internationally, or the extent to which app origin may have influenced linguistic adaptation, cultural relevance, or localisation practices. Given the strong dominance of English-language commercial applications observed across countries in the present review, future research should examine developer origin and regional development patterns in greater detail to better understand how digital mental health resources are distributed, localised, and adapted across different cultural and linguistic contexts.

Finally, the expanding integration of AI within mental health applications warrants critical examination to distinguish genuine technological innovation from marketing rhetoric and to evaluate how AI influences user trust, app selection, and engagement. Attention should also be directed toward app developers and their professional credentials, as these factors may affect perceptions of reliability, content quality, and user confidence. Collectively, these considerations underscore the potential value of establishing a globally recognized certification framework for digital mental health applications, promoting safety, evidence-based practice, and ethical design.