Otrium grows with next-level marketing technology

Introduction

Otrium, the online outlet platform for designer fashion, saw strong international growth in recent years, largely driven by performance marketing. But in a market where competition is increasing and cost per click is rising, growing profitably became harder and harder. Together with Draft Digital, Billy Grace and Talpa Media, plus a consortium of innovative media and technology partners, Otrium developed an entirely new, integrated brand and media strategy. The approach combines smart technology, AI and creativity to make a lasting impact, on brand as well as on performance.

The problem

Otrium was growing fast, but noticed that the performance media it had relied on for years were becoming less efficient. Cost per click rose while conversion rates came under pressure. Profitability declined, and it became increasingly difficult to trace where in the funnel the stagnation started. Having both an app and a website made it even harder to see complete customer journeys.

At the same time, competition intensified. Platforms such as Best Secret and Zalando Lounge were investing heavily in visibility and performance. To avoid being overtaken, Otrium needed a sustainable, scalable growth strategy that went beyond clicks.

Why was a solution needed?

Otrium wanted to move into its next phase of maturity: from fast growth through performance to profitable scale built on brand preference and data-driven insight. That meant:

• Positioning the brand structurally more strongly in the minds of the audience
• Reaching new audiences that are hard to reach through performance media
• Getting a firmer grip on cross-channel attribution, including app and web usage
• Being able to judge branding media on their actual impact on sales

Only an integrated approach would let Otrium keep growing sustainably and position itself as a market leader in an increasingly crowded field.

The solution

The chosen strategy rested on four innovative pillars: advanced data technology, smart media deployment and creative automation.

1. Understanding customer behaviour through Billy Grace

With Billy Grace, Otrium became the first to bring the complete customer journey from both website and app together in one model. Connecting that combined data to the CRM (order data at product level) produced a crystal-clear view of customer acquisition cost per specific channel.

Billy Grace's data science models revealed that the standard algorithms of platforms such as Meta and Google were often over-optimised on existing customers or lower-funnel conversions. The connection proved that:

• Upper-funnel channels were significantly more effective at bringing in new customers than had been assumed.
• The real incremental value of campaigns could be tied directly to long-term customer value.

That hard evidence was the direct trigger for a fundamental shift in media strategy. Because the contribution to growth KPIs was now measurable, Otrium dared to reallocate budget towards broad, brand-building channels. The result was the start of large-scale investment in radio, digital out of home (DOOH) and digital audio, specifically aimed at acquiring new customers at scale and at a healthy acquisition cost.

— Mitch Voskuilen, Co-Founder and CEO at Billy Grace

2. Cross-media campaigns with audio and DOOH

Because Otrium's goal was twofold — building a brand and delivering direct performance — the team looked for a channel mix that moves several KPIs at once. That mix was built on research (including from the IPA) showing that radio delivers impact on both brand and performance KPIs. To achieve a healthy balance of reach and frequency, Otrium entered a strategic partnership with Talpa Media.

To strengthen the radio mix, DOOH was added tactically in locations where a lot of radio is consumed, such as along motorways and in car parks. That contextual link reinforced the message. DOOH was only bought while the radio commercial was on air, made possible through programmatic buying, which allows offline media to be bought at specific moments.

Digital audio was deployed alongside it. Precise targeting on interests, behaviour and moments of use delivered maximum relevance there too. Unlike radio, digital audio allows frequency capping, so contact frequency could be steered to a healthy level across all audiences. Radio reach generally skews towards older audiences, which makes digital audio an important addition for reaching younger ones.

3. Fully automated radio spots through voice cloning

Otrium changes its promotions weekly and activates dozens of brands at unpredictable moments. That made static radio spots impossible. The solution: AI voice cloning. Talpa Media developed a synthetic voice for Otrium.

Voice actor Costian spent four hours in the studio recording sounds and intonations. Those recordings were processed in Audiostack, creating a dynamic system in which text is automatically converted into natural, personalised audio. That made millions of radio spot variations possible, without a studio or voice-over session in between.

"Being able to create millions of radio spot variants with AI voice cloning, without human intervention, is an absolute game changer for audio creation. For Otrium it meant not only speed and scalability, but a huge leap in consistency and personal relevance of the message." — Paul de Beus, Digital Audio Advertising Specialist at Talpa Media

4. Branding held to performance

All impressions, GRPs and media deployment — from radio to DOOH and digital audio — were loaded into Billy Grace automatically. That was essential: without real-time data in Billy Grace, the algorithms could make the wrong budget optimisation decisions.

Because the data was up to date and available in real time, unified marketing measurement could calculate exactly what each channel contributed to the eventual conversion. Instead of relying on outdated last-click attribution, algorithmic modelling accounted for multiple contact moments in the performance valuation.

That meant branding channels such as radio and out of home could be held to the same KPIs as platforms like Meta and Google: cost per acquisition, return on ad spend and contribution to new customer acquisition. It was a breakthrough in how Otrium judged investment in upper-funnel media.

It also allowed steering on effectiveness at campaign level: campaigns with a demonstrable conversion contribution were allocated more budget. That made branding not only steerable but scalable and accountable, and therefore a full building block of Otrium's overall growth plan.

What made this approach innovative

This case broke new ground on several levels:

• A first in tracking: Otrium was the first party in the world to integrate app and web data within Billy Grace
• Performance on branding: branding media were held to performance KPIs through advanced modelling
• AI-generated audio: voice cloning allowed millions of radio spots to be generated automatically, a first in the Netherlands
• Smart media combination: running DOOH around radio moments created cross-media reinforcement
• CRM connection for customer value: linking CRM data to media data showed which campaigns delivered new customers and which channels contributed most to growth

"The collaboration with Talpa Media and Billy Grace shows what is possible when you really let data, AI and creativity work together. The dynamic in this case is unique in the Netherlands, and globally too. And it is rare to have a client like Otrium that shows both nerve and a genuine will to innovate across multiple channels and systems." — Lars Postmus, owner at Draft Digital

Results

The new strategy led to very strong results. Even though branding and longer-term growth were the starting point, these channels in some cases outperformed traditional performance media. The strategy has proven effective and can scale further.

• 4% more revenue compared with 2024, showing that the branding strategy had an impact at top level.
• Direct results on sales KPIs. The total mix of radio, digital audio and DOOH achieved a positive return on investment and a return on ad spend (6.38) comparable with performance media such as social. Branding contributed to performance as well as to brand.
• 41% more brand searches for Otrium (based on Google Ads data) than in the same period a year earlier, while spend was only 7% higher. Search volume was also 2% higher than in 2023, while spend there was considerably lower (16%). The new strategy is contributing to brand recall.
• The share of new customers within the branding channels was 10% higher than Otrium's broad average, showing these channels can deliver new customers.
• In total, 27% more new customers were acquired compared with 2024. In the second half of the year that rose to 84%.
• Return on ad spend for DOOH was on par with, and often better than, performance on social media.
• DOOH was the second best performing channel after Criteo and Google, which is remarkable for an upper-funnel channel. Combined with radio, it proves to be an effective investment.
• Within the radio mix there was significant variation in station performance: Radio Veronica achieved a return 37% above average and will get more focus going forward. Sky and 100% also performed well.
• Alongside reach optimisation, this makes it possible to steer on performance within a traditional media type.
• Significant time and cost savings on audio production. More than 100 spots were recorded without human intervention.

"Thanks to this approach we have developed a scalable brand strategy that contributes directly to our commercial objectives. The combination of creativity, technology and data-driven media deployment makes it possible to genuinely stand out in a complex and competitive market." — Philip Sonneveldt, Head of Growth at Otrium

Next steps

The collaboration with Draft Digital, Billy Grace and Talpa Media continues and is being expanded. The coming period focuses on:

• Always-on upper-funnel media: radio, DOOH and digital audio will be deployed structurally within an always-on strategy. That keeps Otrium top of mind among existing and new audiences, and supports seasonal peaks tactically.
• International scale-up: the strategy is being rolled out in other countries such as Germany, the United Kingdom and Belgium, looking per market at channel mix, media consumption and cultural nuance to maximise local relevance.
• AI-driven personalisation: voice cloning and dynamic creation will be used further to personalise messages by audience, channel, moment and even CRM preferences. These voices are also used for performance assets in Google, Meta and TikTok, giving Costian's voice an even more prominent role.
• Deeper data steering: extra data points are being added within Billy Grace, including optimisation at station level, day parts and geography, making it possible to deploy media pressure more precisely and cost-efficiently.
• Deeper customer value: further integrating CRM and media insight is building towards a next-level attribution model that accounts for customer type, order value, profit margin, retention potential and brand impact.

With this, Otrium continues to build a sustainable and profitable growth engine in which technology, creativity and media come together.

Partners: Draft Digital, Talpa Media, Billy Grace, Turntwo, Adform, Outmoove, Audiostack