Welcome to “Building Localization from Scratch”, the series where we speak to founding localization leaders about what it really takes to build localization departments from the ground up.
This week’s interview is with Mathilde Barbaroux, Localization Lead at Heidi, an AI Care Partner designed to expand clinical capacity by automating administrative work so clinicians can focus on patients.
Today, Heidi supports more than 2.7 million consultations each week across 110 languages in 190 countries, spanning emergency departments, general practice, and specialist clinics.
From LSPs to leadership
Mathilde began her career as a project manager at small LSPs before becoming a freelance French Language Specialist working for global brands like Tinder. She later transitioned to in-house roles, first as a Localization Program manager at Apple, then a Language Growth Manager at Brave.
After years in structured, large-scale localization teams, joining Heidi marked a major change for Mathilde. She initially joined as the Language Growth Manager for France eight months ago, and her quick shift to localization has been a huge step up in terms of ownership, strategy, and decision-making.
Impact through strategy
💡“I need to make sure that what we do has impact.”
Before Mathilde joined, localization at Heidi was focused on building the localization infrastructure, switching Translation Management Systems, and onboarding the initial vendors.
Stepping into the lead role meant Mathilde quickly had to transition from simply taking care of the website and product translations (although she does still work on daily project management tasks) to working on more strategic areas for improvement.
Early on, the go-to-market strategy was still taking shape, meaning the team sometimes had conflicting priorities. Mathilde leveraged data and used market-level insights to guide decisions and prioritize where the team could have the most impact in terms of company goals or user experience.
The localization team structure at Heidi
Besides Mathilde, the compact localization team at Heidi consists of one (soon to be two) loc engineer who focuses on the backend and the product, and four Language Growth Managers (one each for Japan, Spain, Germany, and France).
Although similar to Language Leads, the Language Growth Managers at Heidi are also involved in growth initiatives and partner events. In addition to in-house translation, they create ads, launch specific campaigns, experiment with A/B testing campaigns, and partner with influencers on Instagram, etc.
These roles are fairly unique to the localization industry, and proof of Heidi’s culture of trust in each employee’s expertise:
💡“There’s a trust within Heidi that everyone in each role is a subject matter expert, creating a culture of ownership.”
Localization as an investment rather than a cost
As a product-led AI company, Heidi is scaling rapidly. In this context, isolating the exact impact of localization can be challenging, especially when it happens alongside sales efforts in different markets.
However, while localization may not always be the sole driver of growth, it is a critical enabler. At Heidi, it is clearly positioned as an investment rather than a cost; so much so that it is part of the growth team.
💡“As the localization lead, Heidi is a great place to be. The leadership team genuinely value localization and see it as essential to growing the markets we want to reach.”
Why accuracy and adaptation are non-negotiable
💡“If you want to sell to clinicians and healthcare organisations, you need to have a high degree of accuracy.”
With an audience of clinicians, Heidi must communicate its product clearly and remain fully compliant with regulations across markets.
Localization also plays a role in product development. Medical systems differ significantly across countries due to variations in history, culture, and policy. Even core elements like clinical notes vary in structure and style.
For Heidi, this means going beyond translation to true market adaptation. As Mathilde explains, without this level of hyper-localization, the product simply wouldn’t work.
Managing AI in localization as an AI-led company
As an AI company, you might expect that the localization team is under pressure to adopt an AI-first strategy. However, Mathilde tells us that she has never felt pressured to use AI for the sake of it.
This comes back to Heidi’s philosophy of trusting its employees to make their own decisions. That’s why the localization team has chosen to use AI in projects where it makes sense in terms of cost and speed, and leave it out (at least as a first step) for more creative content and ads.
The next strategic steps
Still early in her leadership role, Mathilde’s focus is on strengthening how the team operates at scale.
Her immediate priority is processes and workflow refinement; creating a consistent cadence that allows her team to work autonomously, without the need for her input and briefing on every task. She also plans to introduce automated QA workflows to support continuous quality improvement.
Looking ahead, Mathilde wants to play a more active role in market-level decision-making in future; deciding which markets they should expand into, and where they should focus their efforts.
The pain of localizing too fast
When we asked Mathilde about lessons learned, it was all related to speed. Moving fast in a high-growth environment meant the team began scaling localization before some foundational structures were fully in place. In hindsight, she would have invested more time up front in building a strong strategic foundation before making any hiring decisions.
Advice for new localization leads
💡“Start with clear directions and expectations from your management.”
Mathilde’s top advice for new localization leads is to align closely with senior management from the outset. Clear goals, expectations, and KPIs make it significantly easier to prioritize effectively and measure success. Investing time at the beginning to understand leadership objectives ultimately sets the entire localization function up for success.
Growth through ownership
Mathilde’s rise into leadership has been fast, requiring rapid adaptation and a strong sense of ownership from the outset. This has been made possible in part by Heidi’s forward-thinking culture, which places trust in employees to apply their expertise and make informed decisions. In this environment, localization is able to operate as a true growth driver rather than simply a support function.
At the same time, the team is deliberate about how it scales. There is a clear awareness that moving quickly must be balanced with thoughtful decision-making; knowing where to invest, where to hold back, and how to maintain quality as the company grows. This is particularly evident in areas like marketing, where a more selective approach to AI ensures that nuance and effectiveness aren’t compromised.
Ultimately, it’s this balance of speed, trust, and strategic focus that underpins Heidi’s approach to global growth and highlights the evolving role of localization as a key contributor to that success.
This interview is the seventh in our “Building Localization from Scratch” series, where we sit down with 10 localization industry leaders to pull back the curtain on what it actually takes to build a localization department from the ground up.
Every hard-won lesson, workflow, and strategy from the series is distilled into our White Paper: The Blueprint for Founding Localization Managers, a practical guide for localization leaders building their function from the ground up.
📢The White Paper launches in June 2026. Register your interest here, and we’ll send it straight to your inbox when it’s ready!