Mentalium - CBT Diary by Voice

I'm building a CBT diary app, and before sinking years into it I wanted to know why this niche has so many corpses in it. So we went through everyone who left the market between 2000 and 2026: 542 digital mental health companies — shutdowns, bankruptcies, acquisitions, quiet dissolutions. Up to 18 coded fields each, at least two independent sources per company, and the report is generated from the dataset, so every fraction in it can be recomputed.

The strongest signal is who signs the check. Where the user pays, 53% of the companies are dead; where an institution pays, 21%. The groups are nearly the same size, 258 against 254, so it isn't a denominator trick. B2C died 2.2 times more often than B2B, and apps sold as a one-time purchase died at 85%, 22 of 26.

The finding that landed on me: a medical co-founder does nothing on its own — 47% exits with one, 47% without. My own team has one.

What this does not show: it's a graveyard, not a random sample, so the shares compare groups against each other and don't predict failure. Funding is disclosed for 59% of the companies, and 67% of the sample is US and UK.

Full report, seven findings with denominators:

https://mentalium.me/en/research/mental-health-startup-graveyard/

If you're building in health right now — who pays in your model, and how long did it take you to find that out?

After two years of trying to keep a CBT diary the normal way, I built the thing I needed.

The problem: CBT works when you actually keep a thought diary between sessions. But typing one during a panic attack or post-work crash is impossible — so most people fill it in from memory two hours before therapy. That defeats most of CBT's effect.

Mentalium fixes it with voice. Press record, speak the five steps of a CBT thought record (situation → automatic thought → emotion → reaction → alternative), and the AI on your phone writes every field. No typing. No cloud. Your voice never leaves the device.

Tech stack: Flutter + Whisper.cpp compiled for iOS Metal GPU and Android JNI. The model (~180 MB) downloads once, then runs fully offline. SQLite for local storage. AES-256 only when the user emails a report to their therapist — nothing else leaves the phone.

iOS is live. Android is coming. Free 7-day trial, $4.99/week or $29.99/year.

Would love feedback from anyone who has tried to build in the mental health space — especially around the offline AI angle and the CBT-specific UX.

App Store: https://apps.apple.com/app/id6764609587

Site: https://mentalium.me/en/