The FACE Self-help App for Fostering Resilience

Resilience will be assessed with the German version (Sarubin et al., 2015) of the Connor-Davidson Resilience Scale (CD-RISC) (Connor & Davidson, 2003). The scale contains 10 items that are rated on a 5-point scale from 0 - Not true at all to 4 - True nearly all the time. A higher score indicates more resilience.

Well-being will be assessed with the Warwick-Edinburgh Mental Well-being Scale (WEMWBS) (Tennant et al., 2007). The scale contains 14 items that are rated on a 5-point scale from 1 - never to 5 - always. A higher score indicates better well-being.

Self-Efficacy for Managing Emotions will be assessed with the PROMIS Short Form v1.0 - Self-Efficacy for Managing Emotions (PROMIS, 2022). The scale contains 7 items that are rated on a 5-point scale from 1 - never to 5 - always. A higher score indicates better emotion regulation skills.

Fear of Negative Evaluation will be assessed with the German short version of the fear of Negative Evaluation Scale (SANB-5) (Kemper et al., 2012). The scale contains 5 items that are rated on a 4-point likert scale from 1 - almost never true to 4- almost always true. A higher score indicates more fear of negative evaluation.

Social avoidance will be assessed with the subscale social-behavioral avoidance from the German version of the cognitive-behavioral avoidance scale (KBVS) (Röthlin et al., 2010). The subscale contains 8 items that are rated on a 5-point likert scale from 1 - not at all applicable for me to 5 - absolutely applicable for me. A higher score indicates more social avoidance.

Problem-solving will be assessed with German version (Graf, 2003) of the short form of the Social Problem-Solving Inventory-Revised (SPSI-R) (D'Zurilla et al., 2002).The scale contains 25 items that are rated on a 5-point scale from 0 - not at all true to 4 - extremely true. The scale contains 5 subscales: positive problem orientation, negative problem orientation, rational problem-solving, impulsive style, avoidance style. A higher score indicates a higher orientation on each subscale.

Self-esteem will be assessed with the German version (Collani & Herzberg, 2003) of the Rosenberg Self-Esteem Scale (Rosenberg, 1965). The scale contains 10 items that are rated on a 4-point scale from 1 - not at all true to 4 - extremely true. A higher score indicates more self-esteem.

Well-being will be assessed with the Warwick-Edinburgh Mental Well-being Scale (WEMWBS) (Tennant et al., 2007). The scale contains 14 items that are rated on a 5-point scale from 1 - never to 4 - always. A higher score indicates better well-being.

Self-Efficacy for Managing Emotions will be assessed with the PROMIS Short Form v1.0 - Self-Efficacy for Managing Emotions (PROMIS, 2022). The scale contains 7 items that are rated on a 5-point scale from 1 - never to 5 - always. A higher score indicates better emotion regulation skills.

Fear of Negative Evaluation will be assessed with the German short version of the fear of Negative Evaluation Scale (SANB-5) (Kemper et al., 2012). The scale contains 5 items that are rated on a 4-point likert scale from 1 - almost never true to 4- almost always true. A higher score indicates more fear of negative evaluation.

Social avoidance will be assessed with the subscale social-behavioral avoidance from the German version of the cognitive-behavioral avoidance scale (KBVS) (Röthlin et al., 2010). The subscale contains 8 items that are rated on a 5-point likert scale from 1 - not at all applicable for me to 5 - absolutely applicable for me. A higher score indicates more social avoidance.

Problem-solving will be assessed with German version (Graf, 2003) of the short form of the Social Problem-Solving Inventory-Revised (SPSI-R) (D'Zurilla et al., 2002). The scale contains 25 items that are rated on a 5-point scale from 0 - not at all true to 4 - extremely true. The scale contains 5 subscales: positive problem orientation, negative problem orientation, rational problem-solving, impulsive style, avoidance style. A higher score indicates a higher orientation on each subscale.

Self-esteem will be assessed with the German version (Collani & Herzberg, 2003) of the Rosenberg Self-Esteem Scale (Rosenberg, 1965). The scale contains 10 items that are rated on a 4-point scale from 1 - not at all true to 4 - extremely true. A higher score indicates more self-esteem.

Resilience will be assessed with the German version (Sarubin et al., 2015) of the Connor-Davidson Resilience Scale (CD-RISC) (Connor & Davidson, 2003). The scale contains 10 items that are rated on a 5-point scale from 0 - Not true at all to 4 - True nearly all the time. A higher score indicates more resilience.

The ZUF-8 is a self-report measure that explores patients' overall satisfaction with the treatment (Schmidt et al., 1989). For this study, the instrument was adapted to explore patients' satisfaction with the Internet intervention studied in this trial. The scale contains eight items that are rated on a 4-point scale from 1 - low satisfaction to 4 - high satisfaction. A higher score indicates more satisfaction with the online intervention. The German version of the ZUF-8 showed adequate psychometric properties with good internal consistency, construct validity, and concurrent validity (Schmidt et al., 1989).

The scale is an abbreviated version of the PANAS following previous research, that used similar EMA items (Oorschot et al., 2013; Wichers et al., 2012).

The items of the coping scale were developed by this research team on the basis of previous research (Daros et al., 2019). They measure different emotion regulation and coping strategies such as reappraisal, avoidance or changing the situation.

These items were developed by this research team as an addition to the emotion regulation items based on feedback from a user testing group. The participants indicate how burdened they feel in different areas.The scale contains 6 items (school/work, family, friends, feelings/thoughts, difficult memories, leisure time) that are rated on a 7-point scale from 0 - not at all to 6 - extremely. Furthermore, participants can indicate burdens in other areas.

These items were developed by this research team. The Items explore the participants emotional state in the last social situation, for example how happy a person felt in the interaction.

First, participants are asked, if they had a social interaction since the last measurement. If participants indicate an interaction, there are 7 follow-up questions about how the participant felt in this interaction. The scale contains 7 items (stressed, well, anxious, understood, irritated, insecure, happy) that are rated on a 7-point scale from 0 - not at all to 6 - extremely.