Senior/Staff Fullstack Engineer, Avatars

synthesia; United States; On-site; USD 140,000 - 200,000; Full time

Benefits offered by this job

25 days leave

Local holidays

Job summary

Synthesia is seeking an experienced engineer to build and ship full-stack product features end-to-end across avatars and generative media. You will own features from idea to production, collaborating with design and product, and delivering reliable, user-friendly experiences.

You will work with frontend, backend, and AI models, evaluate feasibility, iterate quickly, and ship behind feature flags, measuring impact and refining based on real usage.

Qualifications

• Experience building full-stack product features end-to-end in production.
• Comfort with frontend and backend and delivering from concept to implementation.
• Strong product mindset, able to scope ambiguous problems and iterate.
• Experience in 0 to 1 environments, prototyping and learning rapidly.
• Ability to evaluate feasibility and make pragmatic trade-offs in evolving AI systems.
• Focus on reliability and user experience across the stack.
• Willingness to collaborate with product and design and push back when needed.

Responsibilities

• Build and ship end-to-end full-stack features in production.
• Collaborate across frontend, backend, and AI model integration.
• Own ideas from concept through production, with experimentation.
• Work with AI models (third-party and in-house) and assess feasibility.
• Ship behind feature flags, measure outcomes, and iterate.
• Partner with product and design to translate problems into experiments.

Skills

Full-stack development

Frontend and Backend

Product mindset

0 to 1 experimentation

AI/ML-powered products

Feature flags

Cross-functional collaboration

Job description

Synthesia is the world’s leading AI video platform for business, used by over 90% of the Fortune 100. Founded in 2017, the company is headquartered in London, with offices and teams across Europe and the US.

As AI continues to shape the way we live and work, Synthesia develops products to enhance visual communication and enterprise skill development, helping people work better and stay at the center of successful organizations.

Following our recent Series E funding round, where we raised $200 million, our valuation stands at $4 billion. Our total funding exceeds $530 million from premier investors including Accel, NVentures (Nvidia's VC arm), Kleiner Perkins, GV, and Evantic Capital, alongside the founders and operators of Stripe, Datadog, Miro, and Webflow.

About the role

You will work on end-to-end product features across the Avatars and Generative Media domain, building experiences that sit at the core of Synthesia’s product.

You will design and deliver features that combine frontend, backend, and AI model capabilities, helping users create and customize avatars, generate content, and interact with generative systems in a reliable and intuitive way.

You will take ownership of features from idea through to production, working with loosely defined requirements to scope, prototype, and ship solutions that deliver real user impact.

You will work directly with AI models (both third-party and in-house), evaluating what is possible, understanding reliability constraints, and shaping product decisions based on those capabilities.

You will build across the stack, including:

• Backend systems to support feature logic and model integration

• Frontend experiences that allow users to interact with generative features

• End-to-end workflows that connect user input, model output, and product behavior

You will frequently work on 0 to 1 problems, such as introducing new avatar capabilities or generative features, where experimentation and iteration are critical to success.

You will collaborate closely with product and design to:

• Translate user problems into experiments and features

• Validate what works reliably with underlying models

• Iterate quickly based on feedback and real usage

You will ship features behind feature flags, measure outcomes, and continuously refine based on product and user signals.

What we’re looking for

• You have experience building and shipping full-stack product features end-to-end in production environments.

• You are comfortable working across both frontend and backend, and can independently deliver a feature from concept to implementation.

• You have a strong product mindset and can take ambiguous problems, define scope, and iterate towards solutions that deliver user value.

• You are comfortable working in 0 to 1 environments, experimenting, prototyping, and learning quickly rather than relying on detailed upfront specs.

• You can evaluate technical feasibility and make pragmatic trade-offs, especially when working with imperfect or evolving systems such as AI models.

• You care about reliability and user experience, aiming to build features that work consistently in real-world usage.

• You are confident collaborating with product and design, including pushing back when something is not feasible and proposing better alternatives.

• You are willing to debug and work across the stack, wherever the problem is.

• Experience with AI or ML-powered products, experimentation workflows, or feature flagging is a plus, but not required.

The hiring process

1. 30-40min call with our Technical Recruiter

2. 45min call with an Engineering Manager about your past projects

3. 90min Live Coding interview, a collaboration exercise with our Engineer (not Leetcode style)

4. 60min System Design, technical discussion usually about a real problem we had in production

5. 45min call with leadership, focus on examples of collaboration, growth and going through details of your future team

You can find more details on what to expect and how to prepare HERE. The process does not need to take long - we can be done in seven working days.

Other important info

• Our preference is for this role to based either in-office or remote in the following locations: UK, Germany, Switzerland or Ireland. We may also be able to support remote workers in other locations across Europe subject to compliance and right to work checks.

• This is full-time employment only - no contractors possible - usually through OysterHR or a local entity.

• Everyone at Synthesia gets 25 days of leave + local holidays.