UI/UX Design Agency — Istanbul

We design digital products that convert.

UI/UX Design  ·  Frontend Development  ·  Growth Optimization

See Our Work

What we do

Three pillars. One team.

Design, engineering, and growth — aligned around one goal: products that convert and retain.

  • Design

    Research-driven UI/UX design that puts usability first — from concept to pixel-perfect delivery.

    • UI/UX Design
    • Mobile App Design
    • Visual Identity

  • Build

    Figma to production — clean, performant frontend code built with modern React and React Native.

    • Frontend Development (React)
    • React Native Mobile Apps
    • Design-to-Code Handoff

  • Grow

    Sustainable growth through organic search, conversion optimisation, and app store rankings.

    • SEO
    • Conversion Rate Optimization (CRO)
    • App Store Optimization (ASO)

How we work

From brief to launch — fast.

No bloated sprints, no endless feedback loops. A focused process built for shipping.

  1. Discover

    Research, audit, competitor analysis.
    We define the real problem before anything is built.

  2. Design

    Wireframes, prototypes, visual design.
    Every screen mapped and validated before we write a line of code.

  3. Build

    Development & QA.
    Production-ready React or React Native — tested, accessible, fast.

  4. Grow

    Launch, optimize, iterate.
    SEO, CRO, and ASO to compound results after you ship.

Selected projects

Work that ships.

A sample of recent projects across industries and platforms.

  • UI/UX Design 2025

    E-commerce Redesign

    Full UX audit and redesign of a retail platform — simplified checkout flow, new design system, 22% lift in conversion.

  • Mobile Design + Build 2025

    Mobile Banking App

    End-to-end design and React Native build for a challenger bank — onboarding, accounts, payments, and notifications.

  • UI/UX Design + Frontend 2024

    SaaS Dashboard

    Complex data-heavy dashboard redesign for a B2B analytics SaaS — information hierarchy, dark mode, Next.js build.

About Custeo

A small team.
Sharp focus.
Real results.

Custeo is a UI/UX design agency based in Istanbul, working with startups and product teams across Europe and North America. We price in USD and operate fully remote.

We also build our own products. bunudene.com is our UX and LxD testing platform — we test assumptions before we design, so every decision is grounded in real user behaviour. uxanalysisreport.com is an automated UX audit tool that generates actionable reports instantly.

Custeo Dijital Teknoloji Ltd. Şti.

Get in touch

Let's work
together.

  • Email mail@custeo.com
  • Location Istanbul, Turkey
  • We work with clients worldwide.