About us

We grow fast and are always looking for new colleagues if you want to know more feel free to come by and drink a cup of coffee!

Loyalty Rockstars Customer Retention CRM Interim Team Wies Mensink

Wies Mensink

Founding Partner

Wies (1977), our founding partner, is a mom of three kids, fanatic gig-rower (Islands of Scilly), city-swimmer (Amsterdam, New York, Muiden) and kick-boxer. She had a fundamental position at the start of the renewed Bonuskaart concept of Albert Heijn. Her expertises are devising and creating broad customer engagement and creating loyalty concepts. She has a lot of knowledge about MarTech therefore she is able to help with the newest insights and solutions. She has a background in retail and finance. Our dedicated business developer will assist you further with your engagement and loyalty issues.

Loyalty Rockstars Customer Retention CRM Interim Team Justin Tsen Hsiang

Justin Tsen Hsiang

Founding Partner

Justin (1979), has two kids, loves ice hockey and lives in Amsterdam, with his wife and kids. He is an experienced marketer and motivated entrepreneur with years’ of experience at different companies such as Albert Heijn, Route Mobiel, Pepsico and Yourzine. In his last employment at Albert Heijn, he was responsible for the data driven personal deals within the My Bonus loyalty program. After Albert Heijn he founded Loyalty Rockstars and has consulted on and implemented various project specializing in strategy, data and concept development.

Ronald de Groot

Ronald de Groot


Ronald (1986) is dad of two and lives in Baarn. In 2006 he started at a full service digital marketing and communication agency in Utrecht. He was responsible for the setup of a mobile marketing and development label. They developed apps, mobile marketing campagnes and mobile website for clients such as TNT Post, Eneco, Sanoma, Yakult, Walibi, TNT Express, ING, Sprinters and Yellowbrick. After 7 years the label had grown into an independent division with 15 man. After that Ronald made the switch to Yourzine, a more data-driven marketing agency where he developed knowledge in the field of data, mobile and loyalty. His last position was as innovative strategist in which he advised clients such as Albert Heijn, Efteling and NRC to collect and use more than only email data. Within Loyalty Rockstars he is focusing on concept, strategy and business development.

Loyalty Rockstars Customer Retention CRM Interim Team Niels Costerus

Niels Costerus

Project Manager / IT Consultant

Niels (1977) is an avid fan of TV-series, fitness, windsurfing, sailing and good food. He is project manager and MarTech specialist. He gained over 10 years of experience at Telegraaf Media Groep, Cadeaukaarten Nederland and The entertainment Group. He developed e-commerce solutions for companies such as Air Miles, Shell, De Telegraaf and the Nationale Bioscoopbon. Niels lives just outside of Amsterdam and is a father of three kids.

Loyalty Rockstars Customer Retention CRM Interim Team Merel Bulder

Merel Bulder

Project Manager

Merel (1992) started at Loyalty Rockstars as an intern in 2016 and is now a Project Manager. She graduated Business Administration at the Rijksuniversiteit Groningen in 2017. After which she finished the Master Digital Business and Innovation at the Vrije Universiteit Amsterdam. Merel has a big interest in data analytics, but also marketing and the newest technology are part of her interest. After work she likes to go out for dinner, but she also loves to stay home watch a good series or cook for friends.

Olaf Slot

Project Manager

Olaf (1989) started as intern at Loyalty Rockstars in September 2017. Since February 2018 he is a Project Manager. He studies Commercial Economics at the Hogeschool van Amsterdam. Olaf has a lot of affinity with IT, marketing and sales. At Loyalty Rockstars he uses his IT background & marketing skills for new CRM and marketing solutions. Besides his study and job Olaf plays field-hockey with his friends, tries to go on his racing bicycle every week and is a home gourmet chef and likes to enjoy dining with family and friends.

Romy van Kessel


Romy (1998) is currently carrying out her graduation assignment at Loyalty Rockstars. Here she is able to combine her education and interests. Romy studies International Business (and Languages) at the University of applied sciences Utrecht, for which she has lived in Berlin, Copenhagen and Alcalá de Henares. She is mainly interested in internationalisation, culture, marketing and data. She fills her spare time with travel and sports and loves to cook.

Isabel de Bruijn

Growth Hacker & Project Manager

Isabel (1991), has worked for Loyalty Rockstars since March 2019 after doing a growth hacking traineeship at The Talent Institute. She has a background in marketing and sales and worked in different industries such as fashion, fitness, fintech and FMCG – mostly as brand building/business development freelancer for start-ups but alsof for corporates. She has acquired a Bachelor degree in Economics & Business and a Master degree in Business Adminstration (Marketing track), both at the University of Amsterdam. Before she started her studies, she worked for 3 years as an international model and lived in various world capitals. In her free time she loves to travel and practicing different kinds of sports such as kickboxing, pilates and hiit.