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We are Cobalt Sign

Your Mobile App Development Experts

Taking a structured approach to creating successful iOS & Android apps, from idea to market. Specialized in fintech & healthcare industries.


International awards for app development & design


Integrity is our core value


Passionate team of engineers


Agile approach and open communication

Agile & Professional

We build mobile apps using Flutter, Swift & Kotlin or React Native for innovative companies from Europe & worldwide.

For established businesses

seeking to build a mobile app equivalent for an existing web product or a proof of concept app (POC), we act as your specialized mobile team that augments your existing web team’s work. We create mobile specs, UX & UI design to ensure best practices and requirements from Apple & Google are met and collaborate closely with your product team throughout the app development process.

For startups

and new businesses seeking to launch and scale rapidly, we help you translate your high-level ideas into digital products. We typically start by creating your MVP (minimum viable product) to launch and reach the market, followed by validating ideas and building teams to expedite product development processes.


Product Development

Gathering requirements, creating the concept, defining the roadmap. Proof of concept (POC), minimum viable product (MVP), scaling.


UX & UI Design

Rapid prototyping, research, user testing, wireframes and a beautiful design, following Apple's and Google's guidelines, to ensure a successful app with high ratings.


App Development

Native mobile, web and wearable app development using Flutter, Swift, Kotlin, React Native and ReactJS.


Product Launch

Guidance for app stores setup and optimization, QA, deliveries & updates, continuous integration.


Cobalt Sign is not less than the ideal partner you wish to have. We enjoyed the whole process of creating the Trialog app.
We made the best choice to work with the experts from Cobalt Sign, who really developed the app, not simply technically, but involving the whole project team from Belgium, Italy, Germany and Romania in a common process of innovation and creativity.

Ildikó PatakiProject Lead, Trialog - Erasmus Educational Project

Brilliant and intelligent team, precise, professional and extremely on-time, transparent and very friendly. Was a very pleasing and professional collaboration.

Reza PayaCTO ARMNet

A reliable partner.
We needed a mobile app that would allow our customers to connect to their 123FormBuilder accounts from their mobile devices. CobaltSign provided a solution and developed a great mobile app that worked on both iOS and Android. They jumped in and suggested the best technical approach in order to fit the budget and time.

Florin CornianuCEO 123FormBuilder

We love working together with Oana and Arthur from Cobalt Sign. They are highly skilled experts for mobile platforms and combine great UX design and coding skills.

Simon SchweigruberCEO - Dream Production AG

Cobalt Sign delivered professional results within a very short time, which helped us meet the deadline for a product-launch. In addition to the professional results of the accomplished work, we especially want to highlight the quick understanding of our requirements and the structured, professional way of working.

Mark VoorboomProduct Manager - Stb Automatisering & Advies BV

I've had the pleasure of working with the Cobalt Sign team on a few projects and I'm looking forward to working with them again. Using a clean and structured project management approach, oriented to getting things done, they were able to deliver high quality work on amazingly short deadlines.

Andrei MarinescuCTO - Appscend

International Awards

We always love a good challenge, enjoy taking part in competitions and, of course, receiving awards.

Samsung Gear App Challenge

We created a wearable version of our Tea Cup app designed for Samsung Gear 2. It was one of the winners in Round 1 of the Challenge.

Nokia Developer Champion

Awarded to Oana Csertus in May 2013. “Nokia Developer Champion is a recognition and reward program for top mobile app developers from around the world.”

Fast Track to the Mobile App

App design & development competition by Core77 and Microsoft in November 2011. Our app, 1tap2send was one of the notable finalists.

Imagine Cup “Rockstar”

“Windows Phone Rockstar Award” 2010. We reached the top 10 with our app, Hawkeye, a travel trails app, that organised your photos and created a map trail.

Cobalt Sign - Mobile App Development - Team at office
Cobalt Sign - Mobile App Development - Hello App
Cobalt Sign - Mobile App Development - Team at mDevCamp
Our Style

Engineering & Passion

It is all chemistry. We enjoy building mobile apps and staying up to date with the latest news & technologies in app development. The languages of our choice are Swift, Kotlin/Java and React Native.

Our proven chemical formula for the best product = passion + attention to details + UX + tech skills + reliable team + good communication

Our Values

Teamwork & Good Times

We care a lot about team spirit and enjoying time at the office.

Contributing to the community is important for us, we organize free app development courses & we develop pro-bono apps for NGOs.

Cobalt Sign
Cobalt Sign - Mobile App Development - Hello App
Cobalt Sign - Mobile App Development - Team

Let’s talk about your product

Contact us