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We build apps we are proud of.

Cobalt Sign

About us

The Cobalt Sign Team

We are an app development company based in Timisoara, focusing on developing apps on iOS, Android & Windows.

Here at Cobalt Sign, we work together with our clients on their apps, starting from just an idea to product launch.  We like to keep it simple & professional, having a good time along the way.

We believe that passion, hard work, pixel-perfect design and organized communication lead to a great product.

The Founders

Passion Changes Everything

Oana & Arthur Csertus are both software engineers passionate about mobile, technology, tea and travel.

Throughout the years, they received numerous awards at international mobile development contests. In 2011 they decided to focus on app development and start their own company in the heart of Timisoara.

Cobalt Sign - Oana Csertus & Arthur Csertus
A Place for Our Team

The Zen Room

We value team spirit, curiosity and authenticity. From time to time, we come together and discuss our ideas in the Zen Room.

Usually, we gather to review sprints & code. But, we also relax, find inspiration for our apps and occasionally enjoy a cup of tea.


About Our Work Ethic

01. Style

Authentic, agile, open & reliable describe our work ethic. We work with enthusiasm & attention to detail to develop good software.

About Our Workflow

02. Tools

We work best with Slack, JIRA, Bitbucket and Confluence by Atlassian. Occasionally, for fun ideas and office projects, we also use Trello.

About Communication

03. Agile

Basecamp and Asana are our best friends to keep all the projects clean, well-organized and transparent for our customers.


Giving Back to the Community

Hello App is an initiative started by Cobalt Sign in 2014, through which we organize free mobile app development workshops for students.

Hello App has reached its 6th edition. Read more about the workshops and stay tuned for future editions!

About Conferences, Presentations, Training sessions, Workshops and Labs 

Speaking of…

Arthur was at SCUMPT as part of the jury for computer science students who were invited to showcase their mobile app projects.– January 22, 2020

Our travel app, Ready Set Holiday!, got featured in The Telegraph. – January 8, 2020

We organized the 6th edition of our free app development workshop for students from Timișoara. – October 12 – 26, 2019

Arthur was part of the jury and supported IDMSC, a local contest for students organized by UPT & the Multimedia Centre. – May 31, 2019

Arthur spoke about the app store listing on the App Store and Google Play Store at Cowork Timisoara – the Garden. – May 23, 2019

Arthur spoke about the skills & tools we teach our students to use at Hello App and why they are important in app development. – November 16, 2018

We’ve rebranded Mobile Summer to Hello App and held the 5th edition of our event this autumn. – October 13 – 17, 2018

Arthur was part of the jury and prepared some cool prizes for the winners of the IDMSC contest, organized by UPT & the Multimedia Centre. – May 18, 2018

Arthur was part of the jury at the SCMUPT, where computer science students showcased their apps. – January 29, 2018

Oana and Arthur mentored the participants from the Startup Survivor educational entrepreneurship program. – November 17, 2017

We’ve developed apps for the community from Timișoara in collaboration with 3 local NGOs. – June 25 – July 5, 2017

Arthur presented the Google Play Developer Console and its latest feature, the Pre-Launch Reports. – May 17, 2017

Arthur talked about our app, Ready Set Holiday!, and its road to 1 million downloads. – April 12, 2017

Oana & Arthur Csertus mentoring at the first edition of Startup Survivor – November 15, 2016

Oana Csertus & the Mobile Summer 3.0 crew speaking of the outcomes of the 3rd edition of Mobile Summer – October 10, 2016

The Cobalt Team organizing the 3rd edition of Mobile Summer – August 20-28, 2016

Oana Csertus speaking about women in startups – March 16, 2016

Oana & Arthur Csertus speaking of Ready Set Holiday! – January 20, 2016

by Cobalt Sign, a free summer course for high school students to learn mobile development, Ambasada, Timisoara – August 17-29, 2015

Oana Csertus @ Anita Borg Celebration, Timisoara – January 17, 2015

Oana & Arthur Csertus – Mentors /Jury for Mobile and Kids Tracks  – October 18-19, 2014


Oana Csertus @ Timisoara Mobile Development Group Meetup  – September 15, 2014

by Cobalt Sign, a free summer course for high school students to learn mobile development, Colegiul National “C. D. Loga” Timisoara – July 14 – August 1, 2014

Oana Csertus @ Windows Phone Week Timisoara – October 7, 2013

Oana Csertus @ Windows Phone Week Timisoara – October 7, 2013


Oana Csertus @ Ronua Roadshow 2013 – July 9, 2013


Arthur Csertus @ AIESEC IT School 2013, West University – April 24, 2013


Oana Csertus @ AIESEC IT School 2013, West University – April 17, 2013

Arthur Csertus @ TiMoDev Meetup #1 in 2013, Timisoara Business Center – January 20, 2013

Arthur Csertus @ “Recruited in Timisoara”, DIGI24 News Channel – 5th December 2012

Oana Csertus @ Timisoara Mobile Development Meetup – 10th September 2012

Oana Csertus @ ReBranders, AIESEC – August 2012

Oana Csertus @ UXPerts, Brussels – 11th June 2012

Oana & Arthur @ CodeCamp – 2nd June 2012

Oana Csertus @ RONUA Windows 8 Tour – 19th May 2012

Oana Csertus @ ITFest 2012 by OSUT – 6th May 2012

Arthur Csertus @ ITFest 2012 by OSUT – 5th May 2012

Arthur Csertus @ AIESEC University IT School – 9th April 2012

Oana Csertus @ AIESEC University IT School – 8th April 2012

Oana Csertus @ Microsoft Student Partners Windows Phone Labs – March 2012 – Week 3

Oana Csertus @ Microsoft Student Partners Windows Phone Labs – March 2012 – Week 1

Oana Csertus @ Timisoara Mobile Development Meetup #13 – January 2012

Oana & Arthur @ Geekmeet Hackathon @CoworkTM – 10-11 December 2011

Oana & Arthur @ RONUA 2011 Tour – 18th May 2011

Arthur Csertus @ Timisoara Mobile Development Meetup #2 – 14th February 2011

Oana & Arthur @ Timisoara Mobile Development Meetup #1 – 10th January 2011

Oana & Arthur @ eXcite – Microsoft Student Partners Timisoara – 8th November 2010

Oana & Arthur @ GeekMeet #13 Timisoara – 26th September 2010

Oana & Arthur @ RONUA VS2010 Roadshow – 17th July 2010

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