Senior Frontend Engineer

The future of AI — whether in training or evaluation, classical ML or agentic workflows — starts with high-quality data.

At HumanSignal, we’re building the platform that powers the creation, curation, and evaluation of that data. From fine-tuning foundation models to validating agent behaviors in production, our tools are used by leading AI teams to ensure models are grounded in real-world signal, not noise.

Our open-source product, Label Studio, has become the de facto standard for labeling and evaluating data across modalities — from text and images to time series and agents-in-environments. With over 250,000 users and hundreds of millions of labeled samples, it’s the most widely adopted OSS solution for teams working on building AI systems. 

Label Studio Enterprise builds on that traction with the security, collaboration, and scalability features needed to support mission-critical AI pipelines — powering everything from model training datasets to eval test sets to continuous feedback loops.We started before foundation models were mainstream, and we’re doubling down now that AI is eating the world. If you're excited to help leading AI teams build smarter, more accurate systems — we’d love to talk.

About the Opportunity:

We’re growing engineering to support delivering novel product work in a data labeling automation platform powered by GenAI and agents. We’re looking for the next group of passionate and talented engineers who desire to join and grow alongside us in our mission to build and deliver software that democratizes everyone's ability to harness these technologies. 

HumanSignal is looking for a Front-End Engineer who is comfortable working across the stack when necessary. You will be a key part of our efforts to ensure our platform is user-friendly, reliable, and scalable. You will collaborate with backend engineers, product managers, and designers to create intuitive and responsive web applications that meet the needs of our growing user base. This role is ideal for engineers who enjoy creating intuitive and impactful user interfaces and are passionate about building software that democratizes data labeling through AI and automation.

Responsibilities:

• Develop and maintain front-end components for our data labeling platform, focusing on performance, scalability, and user experience.
• Work closely with product, design, and other engineers to translate requirements and mockups into intuitive user interfaces.
• Participate in code reviews, architecture discussions, and the entire development process, from ideation to production.
• Establish standards for front-end development, including code style, maintainability, and best practices.
• Identify areas for improvement in the codebase and drive changes that enhance the overall quality of the product.
• Mentor and provide guidance to junior engineers on best practices and coding standards.

If this opportunity sounds intriguing and you're drawn to engineering challenges, have a strong desire to make a big impact as part of a small, agile team, in an exciting space, we'd love to talk to you.

• Extensive experience developing front-end applications with modern JavaScript frameworks (React, Angular, Vue.js).
• Strong knowledge of HTML, CSS, and JavaScript (ES6+), with a focus on cross-browser compatibility, accessibility principles, and delivering high-quality, maintainable code.
• Familiarity with state management libraries (Redux, Vuex) and front-end build tools (Webpack, Vite).
• Comfort working with backend technologies (e.g., REST APIs, Django GraphQL) and willingness to dive into backend code when needed.
• A keen eye for design and UX, with a drive to build intuitive and visually appealing interfaces.
• High user empathy and a focus on delivering value through thoughtful, well-crafted user experiences.
• A passion and aptitude for impactful communication at a Sr+ SWE IC level, using TDDs, code reviews, presentation, and thoughtful feedback.
• BSCS, related degree or equivalent practical experience

Languages, Frameworks, and Technologies We Use:

Python, django, JS, Typescript, React, OpenAI API, Spark, BigQuery, Kafka, Jest, Cypress, AWS, kubernetes, Postgres & Redis 

Within 1 week, you'll:

• Setup your development environment, and enhance the self-serve documentation and workflows to ensure it’s pristine and effective. 
• Meet your buddy, team, key stakeholders and the founders
• Participate in team meetings and get close to the sprint in progress

Within 1 month, you'll:

• Make multiple production contributions, across small features, enhancements and bug fixes as you ramp up on codebase, systems, workflows, and product.
• Give feedback in retrospectives, bringing in your experiences and a desire to build a world class engineering team.
• Review multiple pull requests, and leverage your convictions as a software engineer to see design patterns, code style and syntax upheld.
• Resolve multiple engineering dependent customer support requests—quickly get to the root cause and resolve complex technical issues.

Within 3 months, you'll:

• Independently drive and fully own development and delivery of complex features, and present on them in company meetings.
• Review PRDs and lead creation or review of TDDs,  
• Experience and give feedback across a quarterly OKRs cycle, and help the team understand and plan its next quarter commitments.
• Continue to engineering team to improve our velocity and predictability
• Contribute to our industry leading Open Source products and community (with over 20K+ users)
• Mentor and guide junior engineers

Within 6 months, you'll:

• Take the lead and own major features collaborating with other engineers for successful delivery
• Leverage your experience to work closely with Product Management, Engineering and Customer Support staff to identify, document and help resolve technical issues and product feature/functionality gaps
• Support and help grow the open source community through your participation in meet-ups, design/code camps and technical speaking engagements
• You will play a key role in shipping highly scalable products and the next evolution in labeling software.

In 1 year, you'll:

• Continue delivering increasingly complex projects
• Play an active role in advancing your career to the next level

At HumanSignal we pay based on regional compensation market rate ranges across the globe. We are hiring for this role across North and South America as well as Europe. The base cash compensation range is $140,000 to $200,000 USD. These ranges are provided by market data and are in good faith. The final offer details are determined by several factors including candidate experience, expertise, as well as applicable industry knowledge and may vary from the pay ranges listed above.

It is an exciting time at HumanSignal, we are a growing startup and at this stage we are constantly evolving. While we have put a lot of thought into your first and most important initiatives, it’s only an example and something we will work on together. We're always learning and growing, so like us this role will evolve and expand. We hope that this opportunity sounds exciting to you and that you consider joining us on our journey!