Senior Fullstack Engineer - AI

Hiya; Barcelona; Híbrido; EUR 50.000 - 75.000; Jornada completa

Descripción de la vacante

A leading voice communication company in Barcelona seeks a Senior Software Engineer to enhance its SaaS platform architecture. This role focuses on backend services and collaboration on AI projects. Ideal candidates have 4+ years of experience and skills in TypeScript, cloud infrastructures, and applied AI. Join a dynamic team committed to innovation and growth in the voice intelligence space.

Servicios

Competitive compensation

Travel opportunities

Supportive team culture

Formación

• 4+ years of backend or full-stack engineering experience.
• Experience with LLMs and integrating model APIs.
• Strong product sense and ownership mindset.
• Familiarity with cloud infrastructure, ideally GCP.
• Excellent communication and self-organization skills.

Responsabilidades

• Continuously evolve the architecture of the SaaS platform.
• Build and maintain REST/gRPC backend services.
• Integrate LLMs via APIs and prompt engineering.
• Collaborate with R&D and product teams on AI models.

Conocimientos

Backend or full-stack engineering experience

Applied AI knowledge

Product sense and ownership

Communication skills

Herramientas

TypeScript

Node.js

React

Postgres

Docker/Kubernetes

Rust

Descripción del empleo

About Us

At Hiya, we’re revolutionizing voice communication. Our mission is to modernize voice with intelligence for security and productivity

Since 2015, when we introduced the first mobile caller ID and spam-blocking apps, we’ve been at the forefront of voice intelligence innovation. In 2016, we partnered with Samsung and AT&T to launch Hiya Protect, the first network-based spam-blocking solution. In 2019, we introduced Hiya Connect, a branded call SaaS platform that helps businesses reach more customers by phone.

Today, our Voice Intelligence Platform supports over 500 million users globally. By using adaptive AI and audio intelligence, it delivers smarter, safer, and more productive voice calls across networks, apps, and devices. Our network & solution partners have grown to include British Telecom, EE, Virgin Media O2, Ericsson, Rogers, Bell Canada, MasMovil, Telenor, FICO, Twilio, and more.

About the Position

This position is part of the Audio Intelligence team at Hiya, who works on building solutions for audio and speech leveraging AI and Deep Learning. Some of our products and models include for example AI Voice Deepfake Detection, Voice Authentication and Voice AI Agents. Some of them are served via API for developers to build on top of (you can check our documentation here) in use cases like contact center operations, communications platforms or media fact checking; others are served as part of a no-code SaaS platform

The Senior Software Engineer is an Individual Contributor (IC) position whose main responsibility is to continuously evolve the architecture of our SaaS platform composed of aREST API, a web console and different demos and integrations. You’ll take part in the design of new services and flows involving CRUD operations, audio streaming and model inference.

While the role is primarily backend-focused, you’ll also have opportunities to collaborate with our R&D and product teams on integrating and experimenting with AI models, both LLMs as well as other architectures. This includes tasks like designing prompts for AI-driven features, consuming external model APIs, and contributing to lightweight model-in-the-loop systems.

What You'll Do

Relevant tasks and technologies, with varying levels of involvement (they are all valued but not rigid day 1 requirements):

• Build and maintain REST/gRPC backend services (TypeScript, Node.js; Rust optional).
• Build web applications and agent interfaces using React or SvelteKit.
• Integrate LLMs via APIs, including prompt engineering, tool calling, and retrieval-augmented generation (RAG).
• Maintain Postgres-backed databases and manage deployments with Docker/Kubernetes (GCP).
• Work on integrations with telephony systems (SIP, VoIP, call routing).

What You’ll Need to Succeed

• 4+ years of backend or full-stack engineering experience.
• Experience (or strong interest) in applied AI: using LLMs, building agents, integrating model APIs.
• Strong product sense and ownership mindset: you care about what you build and how it performs in the real world.
• Comfort working in a fast-moving, iterative environment with real customers.
• Familiarity with cloud infrastructure (ideally GCP) and CI/CD pipelines.
• Desire to use AI tools to improve your own development speed and quality.
• Excellent communication and self-organization skills including working within and with other remote teams.

Bonus Points

• Experience building agentic workflows with OpenAI, Anthropic, or similar APIs.
• Experience with streaming APIs and media pipelines and voice AI platforms.
• Understanding of telephony protocols and systems (SIP, VoIP).
• Experience with LLM evaluation techniques (e.g., A/B tests, GPT-judge, synthetic data).
• Interest in conversational UX and real-time AI applications.

The person in this role must embody Hiya’s key values of: Serving our customers, Doing rather than observing, Improving ourselves and our business, Owning and holding ourselves accountable for success, and Leading by showing up with a POV, engaging in discussion, listening respectfully to others opinions and committing to decisions.

You will have a fast start if you have experience with:

• Rust
• TypeScript
• Cloud environments (GCP)
• Kubernetes
• Postgres
• Using or integrating LLMs via APIs
• Prompt engineering, retrieval-augmented generation (RAG), or basic orchestration of model pipelines

The requirements listed in the job descriptions are guidelines. You don’t have to satisfy every requirement or meet every qualification listed. If your skills are transferable we would still love to hear from you.

More Details

When determining compensation, a number of factors will be considered: skills, experience, job scope, location, and competitive compensation market data.

• Start Date: Immediately
• Status: Full-time (40 hours per week)
• Type: (Hybrid 3 or 4 days p/w in office)
• Location: Barcelona, Spain
• Travel Requirements: Yes. Once a year travel to Seattle for the company off-site. Additional travel might be required to Spain and Budapest
• Department: Product
• Reports to: Director of Product
• Direct Reports: No

This position is based in Barcelona, Spain

We are building a team with a variety of perspectives, identities, and professional experiences. We evaluate great candidates through a business lens and we strongly believe that diversity and unique perspectives make our company stronger, more dynamic, and a great place to build a career.

Our team has won various awards over the last 4 years from Built-in Seattle and Seattle Business Week to #86 on Deloitte Technology Fast 500 and Forbes #1 Startup Employer. Here at Hiya, we are a people-centric company focused on helping each and every one of our employees grow both personally and professionally. We feel that creating a team culture of support and empowerment to challenge the status quo results in an energized and passionate team that is continuously challenged and passionate about the work they are doing. You'll love working here if you are looking for an innovative challenge that is disrupting an industry. Come join us!