Yuja Labs

A product engineering studio for startups and small businesses. We work end-to-end — from early product thinking through the code that ships.

From idea to running product

We work end-to-end with founding teams — or plug in at the stage where you actually need help.

Design + Build
01

End-to-end product builds

Most engagements look like this. We take an idea or an early product and we design it, build it, and ship it — together. Strategy, UX, visual design, and the production-grade engineering to back it. One team across the arc, no handoff between the design and the code.

  • Product strategy·
  • UX·
  • Design·
  • APIs·
  • Infrastructure·
  • Launch·
  • Iterate
02Prototype

Prototypes & Early Systems

From idea to working software. Built so what works on day one is still the foundation to build on.

03AI

AI Applications

Custom workflows, internal copilots, and AI-enabled products designed for real use cases — built into how a team actually works.

04Advisory

Technical Advisory

Fractional CTO and design leadership. Architecture, hiring, product direction — and the decisions in between.

Two ways to work with us

Two ways teams find us: with a project that needs to ship, or with an idea worth building together.

Model 01

Project work

We design and build the product with you — from early definition through launch — as a single integrated team across strategy, design, and engineering.

Engagement: Paid, sized to the workTeam: Senior product + engineering, end-to-endFit: Founders and small teams
Model 02

Building together

For small businesses with an idea we believe in but can't fully fund, we build alongside the founder at a reduced rate, with a stake in the outcome.

Engagement: Reduced rate + revenue shareFit: Small businesses with conviction

A two-person studio

  • 2026
  • Denver
  • Remote, worldwide
Jane · MikaëlCo-founders

Jane Castellani

Co-founder · Product Design & Strategy

Former staff product designer at AirDNA, where she led the design team across two brands and five product lines. Earlier: product design and management at AE Studio across multiple clients, including EVgo's B2B 0→1 line; before that, design, PM, and consulting work spanning NYC, Paris, and Denver. Also co-founding konteen, a consumer AI product.

Education
UPenn

Mikaël Castellani

Co-founder · Engineering & AI

Former VP of Engineering at Tawkify, where he led a team of 5–12 through a platform rewrite and the company's AI adoption across product and operations. Earlier: senior front-end at Symphony.com (Paris/NYC) growing the team from 2 to 20, and R&D at ActiveViam. Master's in Computer Science from EPFL and engineering from Centrale Paris.

Education
EPFL · Centrale Paris