Julian Clemens

Julian Clemens

I'm Julian, 20 years old. I started two B2C brands as a teenager and now build AI video systems at Knowunity.

With my classmates in front of the international school in Tokyo
Age 15 · Tokyo

2021

  • Moved to Tokyo, Japan for a year
  • Went to an international school
  • Improved my English skills and learned Japanese
  • This is where I first came in contact with a different culture and learned about entrepreneurship
My kanji reading exercise at school in Tokyo
The Aestlive Instagram profile
Age 16 · Germany

2022

  • Moved back to Germany
  • Launched Jumirr (formerly Aestlive) to make discovering fashion products easier
  • First revenue on day 3 after launch
  • Met my co-founder through TikTok, 1 month after launch
Building my first website, Aestlive, myself in Elementor
Twofourtyseven: a skeleton watch, a desk full of watches and the Shopify dashboard showing €10.02K in sales this month
Age 17

2023

  • Founded Twofourtyseven, my second company, a DTC watch brand
  • Hit €10k monthly revenue within 8 months
  • Jumirr hit 100k followers in September, 10 months after launch
  • Drove 100K+ clicks for W Concept and generated €50K in clothing sales for Weekday within just a few months
Jumirr on TikTok (30.8K followers) and Instagram (71.7K followers)
Selfie at the Golden Gate Bridge in San Francisco, on my solo trip
Age 18

2024

  • Launched the Jumirr iOS app
  • Scaled it to 70k downloads and built an Android waitlist of 50k+
  • Self-funded solo trip to Tokyo, Seoul and San Francisco during summer break
The Jumirr app: verified brands, swipeable product cards and outfit details with a buy link
With my co-founder on the beach near Montpellier
Age 19 · Montpellier

2025

  • Graduated high school
  • Sold Twofourtyseven for five figures to focus on Jumirr
  • Moved to Montpellier (South of France) on my own 2 weeks after graduating, to build the Jumirr app with my co-founder, without speaking French
Flippa email: twofourtyseven.com successfully sold
With part of the Knowunity team at the office in Berlin
Age 20 · Berlin

2026

  • Moved to Berlin
  • Joined Knowunity, a Series B EdTech company with 1M+ daily active users
  • Took ownership of AI video, content automation and push notifications
  • Manage paid ads for France, the UK and Romania
  • Attended YC Startup School Paris
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My projects

Jumirr

Founder · 2022–2026

Founded Jumirr – make fashion more accessible for everyone.

When I was 16 I noticed that you can only shop by scrolling through websites with thousands of products. And when you see an outfit on social media you can't buy it right away. I wanted to change this with Jumirr.

Jumirr on Instagram The Jumirr app
Three screens of the Jumirr app: an outfit feed, a shoppable item from an outfit and the brand finds swipe deck Jumirr on TikTok (30.8K followers) and Instagram (71.7K followers): over 100K combined App Store downloads of the Jumirr app: 72.5K in total, peaking at almost 4K a day around New Year 2024

What I built

I started Jumirr on my own as a website with a few features and grew it from there. I later met my co-founder through TikTok. While he built the app, I shaped the product and drove growth. I built our social media presence, reaching millions of people every month. I also hired a few employees (part-time) to help with operations.

Challenges

The workload. Balancing school with the workload of Jumirr. So I hired Kiko from our community and later two more people.

Managing people. Managing them at 16 was hard because I had to tell them exactly what to do instead of assuming (which I did).

What I learned

Affiliate marketing is low-margin and not recurring, so you have to keep selling every single month.

With my first employees I learned that I have to tell people exactly what I need instead of assuming they know.

Basics of starting a company. This was my first company.

Results & traction

Day 3
first revenue after launch
100K+
followers, Instagram + TikTok
70K+
iOS app downloads
€185K+
trackable affiliate GMV

All from affiliate marketing. €50K+ of it for Weekday and Jaded London. Mostly a US audience then Germany.

Anything else

I decided to move on from Jumirr and join Knowunity because the business wasn’t sustainable enough for the effort involved. Over time, I also realized that fashion and the fashion industry was no longer something I felt strongly passionate about.

Twofourtyseven

Founder · 2023–2025

Started a watch brand on top of Jumirr.

I was already selling a good amount of products through Jumirr and thought: I could scale this up as my own brand and make more money with it. So I built a watch brand focused only on skeleton watches. It reached over €10,000 in revenue per month when I was still 17 and was acquired by a Luxembourg-based company for five figures.

Launch banners for two Twofourtyseven watches: The 207 and The S.9.4 A Twofourtyseven skeleton watch with a square case and mesh strap A desk covered in Twofourtyseven S.9.4 watches, one on my wrist Shopify dashboard showing €10.02K in sales in one month, next to the Flippa email: twofourtyseven.com successfully sold

What I built

I built a brand from 0 to almost 1,000 orders (Shopify + Etsy). I selected a supplier network in China and with them produced and co-designed the watches. I came up with the branding myself (only skeleton-look watches) and handled the logistics: getting the product shipped to my house from China and then distributed to customers globally.

Challenges

Cashflow management: buying stock first and then selling it. Managing thousands of euros while being young. Marketing, branding and logistics. With the responsibility of doing all of this alongside school and my other business, Jumirr.

What I learned

How to deal with suppliers in China. How to sell low-priced ($20–50) and higher-priced items ($250) and how to create a brand around a product. How to drive growth for my own products. And, thinking back, the quality of the product: that's something quite important.

Results & traction

€10K+
revenue per month, at 17
~1,000
sales
5 figures
acquisition

Acquired by a Luxembourg-based company in September 2025. I sold it because I moved to France to work on Jumirr.

Knowunity

Growth Analyst · 2026–today

Built and automated Knowunity's entire AI video pipeline.

Knowunity is a Series B EdTech company with over a million daily active users.

Knowunity
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How the pipeline works Click to enlarge

Inputs feed each step ↓   then each step hands over to the next →

  • Curriculum + exam dates
  • Textbooks + pacing guides
  • App demand report
  • TikTok keyword search
1CalendarRough planning of what content goes out when.
  • Official curriculum PDFs
  • Common mistakes students make
  • My drafting rules
2Content qualityMakes sure the topics from the calendar are actually relevant and the right ones.
  • Weekly post mix
  • Hook library
  • Style library
3Post specsPredetermined posting styles I created beforehand.
  • Code-drawn graphics
  • Knowie characters
  • AI visuals
4RenderThe creation of everything: slides, visuals, videos.
  • Week trigger
  • Captions + hashtags
5DistributePosting through a distribution partner I found.

Feedback loop · comments, solve rates and performance flow back into the calendar, the content checks and the post styles

Views per week across all AI video posts, growing from 2K in mid-August to 379K in the week of October 19

What I built

I built the entire AI video pipeline from the ground up (structure on slide 2 above). I also run the paid ads for France, GB and Romania. With a colleague I'm in charge of push notifications, where we're responsible for reactivating millions of users.

Challenges

I am working in a company and not on my own anymore. It was hard to find the balance between over- and under-communicating.

I had never worked on pipelines or automations before. When I joined Knowunity I had to learn this from scratch by myself.

What I learned

The basics of engineering a pipeline. Working on one big mission as a team.

Communication and working across teams and not on my own.

Different AI video tools and how to use them properly.

Results & traction

1.1M+
views in the first 9 weeks
450K
views in the last 7 days
2×
push open rates, two weeks in a row

We've seen good traction on the AI videos, almost doubling the views every week. On my smaller tasks like push notifications, we've doubled open rates two weeks in a row.

Anything else

My initial intention was to join Knowunity only for a few months and then study Geography at LMU in Munich. However, I decided to stay at Knowunity because I saw more opportunities to learn in Gen AI and to grow as a person.

Along the way

Antler logo

Accelerator · 2025

Accepted to Antler and said no

What
We got accepted to Antler's residency programme with Jumirr. To join, we would have had to drop the company and start a new idea. We decided not to.
Looking back
It might have been wise to go. Companies like Peec AI came out of that batch.
Lesson
Jump on opportunities.
Selfie at the Golden Gate Bridge on my solo trip

Solo trip · 2024

Seoul, Tokyo, San Francisco at 18

What
A world trip in my summer break of high school, fully financed by my earnings, mainly from Twofourtyseven. Tokyo to visit friends and San Francisco for the first time.
Challenge
Doing it all by myself at 18 and being sick on the trip.
Takeaway
Meeting new people and discovering new cultures.
At Y Combinator Startup School in Paris, in front of the master stage

Event · 2026

YC Startup School Paris

What
Went to Y Combinator's Startup School in Paris and met a lot of different people.
Takeaway
A cool event and actually the only one where it wasn't cringe to network and talk to people.

Get in touch

juli.clemens@icloud.com