Multimedia Appendix 2: Full content analysis coding framework and illustrative quotes of all themes and subthemes identified.
Major theme	Quotes	Description/guidelines
1. Accessibility	Any reference to the quality of app being easy to obtain or use including comments around convenience, simplicity and efficiency. Any mention of accessibility in terms of inclusiveness for people with disabilities (e.g. dyslexia). Exclude: generic statements with no specific example of accessibility problems or opportunities for example ' Just plain does what it says it does' (too generic).
1.1. Simple/easy to use	'This app is simple and allows for easy thought record keeping' 'A clutter free interface'
1.2. Efficiency	'This app is an efficient and interesting way of keeping track of the day'
1.3. Cost	'Finally a free app I would pay for!' 'I like the app but, whenyouhave to pay it's ridiculous!! I meanpaying for mental and my own mental health?!'
1.4. Inclusivity	'I have a coordination disorder so prefer a mobile app to a paper diary'
2. Flexibility	'The app gives you the ability to add emotions of your own, and has a much broader spectrum of emotion to choose from than other similar apps' 'It's precise and let's you rate as many times as you need to in one day and charts each individual mood' 'Would like to see some features like the ability to edit an entry rather than delete it and resubmit'. 'I use it to vent...I haven't reached a character limit yet...and I am grateful for that!'.	Any reference to flexibility or options within the app. Flexibility includes user comments on the ability to customize or personalize a certain aspect of the app, for example, custom emotions or , choosing a color theme.
3. Technical features	Any mention of a technical app feature either structural or functional including comments on data, bugs and security features. Exclude: generic technical comments that do not specify a particular feature of engagement or technical issue for example 'loved it a lot before the newest update, still like it just not as much' (no specific technical feature mentioned)
3.1. Data loss/backup/saving	' I loved this app! UNTIL I discovered that after using it for a few months it was deleting all of my entries each month. When I figured this out I was super upset, it was like someone deleted my journal. This sucks. '
3.2. Bugs/display errors/ app entry issues	' Hi, i don't see the day. I was about to input my emotion when I don't see the dates. '
3.3. Export/share/sync	' Wish it would export mood entries as well the mood graph I thought that this mood tracker fit most of my needs for information that I would like to track but when I went to export the data to share with my healthcare provider, I saw that it exports the graph but none of the details! I think that it would be a much more powerful tool if we could share that information as well. '	Any mention of a technical app feature either structural or functional including comments on data, bugs and security features. Exclude: generic technical comments that do not specify a particular feature of engagement or technical issue for example 'loved it a lot before the newest update, still like it just not as much' (no specific technical feature mentioned)