Background: Online counseling chat services are increasingly used by young people worldwide. A growing body of literature supports the use and effectiveness of these services for adolescent mental health. However, there is also a need to provide an overview of the main existing resources to identify unmet needs and gaps in the field. Objective: This study aims to provide an overview of existing online counseling chat services targeting individuals aged 12-30 years in 4 European countries (Belgium, Finland, Hungary, and Spain), and to identify potential needs and gaps by comparing the collected data with recognized quality standard criteria that define the best practices in the field of counseling. Methods: A web search was conducted in the 4 participating countries using the same keywords to identify the main chat services. The final selection of chat services was made using a stratified purposive sampling method. A common data extraction database was developed to record information from these websites. Finally, the extracted information was compared against the fulfillment of 7 selected criteria from the Child Helpline International Quality Standards Framework. Additionally, certain chat characteristics were compared with the number of Child Helpline Quality Standard criteria fulfilled. Results: The search identified a total of 66 service providers offering 71 different chat services. Nongovernmental organizations accounted for more than half of the total service providers42 of 66 (64%). Additional helplines, such as hotlines, were also available through 54 of 66 (82%) service providers. Artificial intelligence tools were incorporated into 6 of 66 (9%) chat services. Differences were observed between countries; for example, the use of volunteers as counselors was predominant in Hungary and Belgium. Topic-specific chat services were common in Belgium and Spain, whereas in Finland and Hungary, chat services generally welcomed a wide range of topics for young people to discuss. Comparisons with Child Helpline International's recommendations revealed some gaps-for example, only 9 of 71 (13%) chat services operated 24 hours a day, and only 10 of 71 (14%) offered interactions in minority groups or foreign languages. Additionally, the use of free social media platforms for chat services was prevalent in some countries, which could compromise users' privacy. Being part of the Child Helpline International consortium was marginally associated with meeting a higher number of standard criteria (beta coefficient 1.55; P=.08). Conclusions: This study provides a comprehensive overview of existing online chat counseling services in 4 European countries. Our findings suggest that some existing chat services for young people could be improved in areas such as accessibility, data security, and the inclusion of vulnerable groups.