Freelance Full Stack Web Developer Jobs in Wisconsin

Join us at Zendesk, where we're on a mission to power exceptional service for every person on the planet. We're accelerating that ambition by building products rooted in AI, automation, and intelligent customer experiences, because behind every interaction lies an opportunity to make a human connection.

We're seeking a Senior Full Stack Engineer to build the real-time voice AI product that makes live conversations feel natural and reliable. Your work will reduce latency, improve conversation flow, and make voice interactions an effective channel for AI-driven support.

• Design and implement backend services powering real-time voice conversations, focusing on latency, reliability, and observability.

• Build integrations for telephony, WebRTC, real-time audio processing, and external AI/speech services.

• Ship end-to-end product features across backend systems and user-facing web experiences when required.

• Improve platform reliability and performance: monitoring, tracing, autoscaling, and failure recovery.

• Address real-time interaction challenges such as turn-taking, interruptions, responsiveness, and graceful handoff to humans.

• Partner with product and design to deliver voice experiences that feel polished and human.

What you bring to the role

• Solid backend fundamentals with experience designing APIs, async systems, and scalable integrations.

• Hands-on experience with real-time systems (WebRTC, WebSockets) or telephony protocols.

• Product-driven engineering mindset - you ship user-facing features and care about UX quality.

• Ability to debug and optimize latency and reliability issues in production systems.

• Enjoys cross-functional collaboration with product, design, and ML/speech teams.

Basic qualifications

• 3+ years building production software, with significant backend engineering experience.

• Experience with real-time or event-driven systems (WebRTC, SIP, streaming APIs).

• Proficiency in Python or equivalent backend languages and async architectures.

Preferred qualifications

• Experience with telephony stacks, SIP, media servers, or speech/ASR/TTS integrations.

• Familiarity with LLMs, speech models, or conversational AI production infrastructure.

• Experience on fullstack teams shipping both backend and frontend user experiences.

• Expertise in diagnosing performance and reliability issues under real-time constraints.

The intelligent heart of customer experience

Zendesk software was built to bring a sense of calm to the chaotic world of customer service. Today we power billions of conversations with brands you know and love.

Zendesk believes in offering our people a fulfilling and inclusive experience. Our hybrid way of working, enables us to purposefully come together in person, at one of our many Zendesk offices around the world, to connect, collaborate and learn whilst also giving our people the flexibility to work remotely for part of the week.

As part of our commitment to fairness and transparency, we inform all applicants that artificial intelligence (AI) or automated decision systems may be used to screen or evaluate applications for this position, in accordance with Company guidelines and applicable law.

Zendesk is an equal opportunity employer, and we're proud of our ongoing efforts to foster global diversity, equity, & inclusion in the workplace. Individuals seeking employment and employees at Zendesk are considered without regard to race, color, religion, national origin, age, sex, gender, gender identity, gender expression, sexual orientation, marital status, medical condition, ancestry, disability, military or veteran status, or any other characteristic protected by applicable law. We are an AA/EEO/Veterans/Disabled employer. If you are based in the United States and would like more information about your EEO rights under the law, please click here.

Zendesk endeavors to make reasonable accommodations for applicants with disabilities and disabled veterans pursuant to applicable federal and state law. If you are an individual with a disability and require a reasonable accommodation to submit this application, complete any pre-employment testing, or otherwise participate in the employee selection process, please send an e-mail to peopleandplaces@zendesk.com with your specific accommodation request.