Hi, I'm Justin.
London based Product Designer of 12+ years
Current
Staff Product Designer at Not On The High Street
AI Shopping Tool, Conversion, and Retention Strategy
Previous
Lead Product Designer at Growth·Design
Lead Product Designer at Bother
Founding Product Designer at Trutify
Product Designer at TouchNote
Other
Creator of Make Like The Greats (Podcast with 100,000+ listens)
Founder of Appfilm Media (Started at age 14)
Media Coordinator for IUFoST Conferences (x3)
Current
Staff Product Designer at Not On The High Street
AI Shopping Tool, Retention Strategy, Shop Conversion
Previous
Lead Product Designer at Growth·Design
Lead Product Designer at Bother
Founding Product Designer at Trutify
Product Designer at TouchNote
Other
Creator of Make Like The Greats (Podcast with 100,000+ listens)
Founder of Appfilm Media (Started at age 14)
Media Coordinator for IUFoST Conferences (x3)
A little intro…
A talk I gave on our product vision at All Hands, 2025
A talk I gave on our product vision at All Hands, 2025
An important life goal realised: Travelling Asia
An important life goal realised: Travelling Asia
Working with mentors: Dan and LX of Growth·Design
Working with mentors: Dan and LX of Growth·Design
Japan: Half my heritage, and most of my inspiration
Japan: Half my heritage, and most of my inspiration
My dad: a man who took work, and me, seriously
A fun, 1.5 min read...
The day I became a better designer
At 14, I built my first website and started earning money publishing articles online.
At 16, I joined a startup building software for retailers like M&S, Waitrose, and Uniqlo.
At 19, I dropped out* of UAL to design apps, websites, and tools for startups full-time.
I always knew software was powerful.
But over the next 10+ years, I realised something deeper.
The best-performing designs weren't just functional.
They tapped into human psychology.
Because UX doesn't happen on a screen…
It happens in the user's mind.
So I went looking for the best minds to learn from.
Turns out I already knew who they were...
Alongside Kahneman, and Ariely, I'd been studying Growth.Design's case studies
to understand the behavioural principles that most shape UX.
So I emailed the founders, Dan and Louis-Xavier.
(With 130,000+ subscribers, I didn't expect a reply.)
They replied the next day.
Would I try making a case study in their style?
Hell yes.
They loved it.
Then came a second experiment: a hands-on format for teaching a concept deeply.
I did that too.
Within two weeks, I'd learned the truth of the old saying:
if you want to learn something, teach it.
59 emails later, we began working together.
At 14, I built my first website and started earning money publishing articles online.
At 16, I joined a startup building software for retailers like M&S, Waitrose, and Uniqlo.
At 19, I dropped out* of UAL to design apps, websites, and tools for startups full-time.
I always knew software was powerful.
But over the next 10+ years, I realised something deeper.
The best-performing designs weren't just functional.
They tapped into human psychology.
Because UX doesn't happen on a screen…
It happens in the user's mind.**
So I went looking for the best minds to learn from.
Turns out I already knew who they were...
Alongside Kahneman, and Ariely, I'd been studying Growth.Design's case studies to understand the behavioural principles that most shape UX.
So I emailed the founders, Dan and Louis-Xavier.
(With 130,000+ subscribers, I didn't expect a reply.)
They replied the next day.
Would I try making a case study in their style?
Hell yes.
They loved it.
Then came a second experiment: a hands-on format for teaching a concept deeply.
I did that too.
Within two weeks, I'd learned the truth of the old saying:
if you want to learn something, teach it.
59 emails later, we began working together.
During those next ~2 years, I made 14+ case studies on how psychology shapes:
(And more.)
This work sharpened my ability to design for how people actually behave, and to tie that to real business impact.
Dan and Louis-Xavier have also coached me personally, refining my instincts along the way.
Charlie Munger said:
"If you don't get psychology, you're not going to be a very good businessman."
Now I don't just get it.
I leverage it.
👆 I also completed the Product Psychology Masterclass course that they teach.
*Whilst I attended University of Arts London (LCC), studying Information and Interface Design (BA), I dropped out at 19 years old to pursue my preferred method of education: building real products for people with real business needs.
A fun, 1.5 min read...
The day I became a better designer
At 14, I built my first website and started earning money publishing articles online.
At 16, I joined a startup building software for retailers like M&S, Waitrose, and Uniqlo.
At 19, I dropped out* of UAL to design apps, websites, and tools for startups full-time.
I always knew software was powerful.
But over the next 10+ years, I realised something deeper.
The best-performing designs weren't just functional.
They tapped into human psychology.
Because UX doesn't happen on a screen…
It happens in the user's mind.**
So I went looking for the best minds to learn from.
Turns out I already knew who they were...
Alongside Kahneman, and Ariely, I'd been studying Growth.Design's case studies to understand the behavioural principles that most shape UX.
So I emailed the founders, Dan and Louis-Xavier.
(With 130,000+ subscribers, I didn't expect a reply.)
They replied the next day.
Would I try making a case study in their style?
Hell yes.
They loved it.
Then came a second experiment: a hands-on format for teaching a concept deeply.
I did that too.
Within two weeks, I'd learned the truth of the old saying:
if you want to learn something, teach it.
59 emails later, we began working together.
During those next ~2 years, I made 14+ case studies on how psychology shapes:
(And more.)
This work sharpened my ability to design for how people actually behave, and to tie that to real business impact.
Dan and Louis-Xavier have also coached me personally, refining my instincts along the way.
Charlie Munger said:
"If you don't get psychology, you're not going to be a very good businessman."
Now I don't just get it.
I leverage it.
👆 I also completed the Product Psychology Masterclass course that they teach.
*Whilst I attended University of Arts London (LCC), studying Information and Interface Design (BA), I dropped out at 19 years old to pursue my preferred method of education: building real products for people with real business needs.
Growth·Design
"Most designers focus on trends. Justin's approach starts from psychology, from how people actually think. That matters more every year, as AI commoditises interfaces and code. Any product team hiring a designer would be lucky to get him."
Dan Benoni
Co-Founder, Growth·Design
You
Let's think through it together…
Share what you're building and where you feel its stuck,
I'll give you my take!
justincampbellplatt@gmail.com
Copy my address
linkedin.com/in/justincampbellp/
You
Let's think through it together…
Share what you're building and where you feel its stuck,
I'll give you my take!
justincampbellplatt@gmail.com
Copy my address
linkedin.com/in/justincampbellp/
You
Let's think through it together…
Share what you're building and where you feel its stuck. I'll give you my take!
justincampbellplatt@gmail.com
Copy my address
linkedin.com/in/justincampbellp/