Who writes this site?
I am Henry Lightfoot, an independent iOS developer in the UK. I studied Computer Science at the University of Reading and I build small, private apps: Bifocal for DBT, and Anneal for Internal Family Systems. I am not a clinician, and nothing on this site is clinical advice.
I use DBT myself. Bifocal began as the app I wanted between sessions: a diary card that took minutes rather than an evening, a Chain Analysis that kept the detail, and an export that handed my therapist the sheet she already used. The app's own caption is “from one DBT patient to another”, and it is the reason the guides are written from practice rather than from a keyword list.
Why does Bifocal have no account?
Because the contents of a diary card are about as sensitive as app data gets. Entries are stored in a local database on the iPhone, with optional sync to your own private iCloud; there is no sign-up, no email address and no server holding a copy. Analytics are off unless you turn them on, and there is no advertising. The full position, including what the host of this website sees, is in the privacy policy.
How are the guides written?
Each guide starts with the skill as it is taught in DBT, then explains it in plain language, with the situations where it tends to fail. I check the descriptions against the published skills handouts and against how the skill is implemented in the app. Where a claim is uncertain, the guide says so: for example, that apps have far less evidence behind them than DBT itself does.
Posts carry a publication date and, when they are materially revised, a separate “last updated” date. The RSS feed and the llms.txt index are generated from the same Markdown at build time, so they cannot list an article that does not exist.
How are DBT apps compared?
The iPhone comparison is written by the person who makes one of the apps in it. That is a conflict of interest, so the page says so at the top, names each competitor's genuine strengths, and gives the criteria before the verdict. Prices, ratings and update dates were read from the App Store listings in October 2026. There are no affiliate links and no paid placements: the only money changing hands is the optional £3.99 lifetime upgrade, paid to Apple in the App Store.
Bifocal, the DBT app for iOS is unrelated to opticians, eyewear or lens retail. The name is a reference to the app's two focal points: the daily card and the longer work behind it.
What this site is not
It is not therapy, diagnosis, risk assessment or a crisis service. If you are in immediate danger, contact your local emergency number. For urgent mental-health support in the UK, contact NHS 111 or the Samaritans on 116 123. An app can support the work you do with a clinician; it cannot replace it.
Contact
Questions about the app, a bug, or a correction to a guide: use the support page or the contact form on henrylightfoot.co.uk. I also post development updates on LinkedIn, and the code for other projects is on GitHub.