Frontend Engineer

ActAI; Greater London; On-site; GBP 70,000 - 110,000; Full time

Job summary

ActAI is seeking a Web Frontend Engineer to build core experiences such as Chat, Notes, Calendar, Docs and Sheets. You will own complex, interactive surfaces from architecture to implementation, collaborating with product, design, backend and AI engineers to make AI a native part of user workflows.

You will drive real-time interactions, streaming AI responses and model-driven experiences while ensuring performance, accessibility and cross-browser reliability across ActAI apps.

Qualifications

• Experience building production web applications using React and TypeScript.
• Strong understanding of frontend architecture, state management and performance.
• Experience with real-time systems, WebSockets, streaming APIs, or collaboration features.
• Able to independently own features from technical design through production.

Responsibilities

• Build major web experiences across Chat, Notes, Calendar, Docs and Sheets.
• Develop complex interactions including real-time messaging and collaborative editing.
• Create reusable frontend architecture and components for ActAI apps.
• Integrate streaming AI responses and model-driven experiences into workflows.
• Ensure frontend performance, accessibility and cross-browser reliability.

Skills

React

TypeScript

Frontend architecture

State management

Real-time systems

UI judgment

Independent ownership

Education

Bachelor's degree or equivalent in CS/engineering

Tools

Next.js

HTML/CSS

WebSockets

REST/GraphQL

Node.js

Job description

There are over 5 billion users using basic applications today such email, notes, tasks, calendar and they're not AI-native. Our mission is to build proactive applications for anyone in the world, who are not used to complex prompting. We aim to bring intelligence to conversations, errands, organising and workflows, with minimal prompting.

Our product focuses on achieving high reliability for long-running workflows, persistent context, and real-world task completion. We believe products will greatly reduce hallucinations.

Our objective is to organise anyone's life, allowing us all to spend time on valuable and meaningful things.

About ActAI

There are over 5 billion users using basic applications today such email, notes, tasks, calendar and they're not AI-native. Our mission is to build proactive applications for anyone in the world, who are not used to complex prompting. We aim to bring intelligence to conversations, errands, organising and workflows, with minimal prompting.

Our product focuses on achieving high reliability for long-running workflows, persistent context, and real-world task completion. We believe products will greatly reduce hallucinations.

Our objective is to organise anyone's life, allowing us all to spend time on valuable and meaningful things.

Role

As a Web Frontend Engineer, you will build the core web experiences, including Chat, Notes, Calendar, Docs and Sheets.

You will own complex, highly interactive product surfaces from architecture through implementation, working closely with product, design, backend and AI engineers to make AI a native part of how users communicate, write, organise and work.

What You'll Own

• Build major web experiences across Chat, Notes, Calendar, Docs, and Sheets.
• Develop complex interactions including real-time messaging, collaborative editing, rich-text editing, scheduling, tables, and spreadsheets.
• Build reusable frontend architecture and components that work consistently across ActAI applications.
• Integrate streaming AI responses, proactive actions, and model-driven experiences directly into product workflows.
• Own frontend performance, responsiveness, reliability and accessibility across browsers and devices.
• Work closely with product and design to take ideas from prototype to production quickly.

What We're Looking For

• Strong experience building complex, production web applications using React, TypeScript and modern frontend technologies.
• Deep understanding of frontend architecture, state management, browser APIs, and performance.
• Experience building highly interactive products such as chat, collaboration, productivity, document editing, calendars, or workspaces.
• Experience with real-time systems, WebSockets, streaming APIs, or collaborative interfaces.
• Strong product and UI judgment with attention to interaction details.
• Able to independently own features from technical design through production.

Outcomes

• Users can communicate, write, organise and collaborate seamlessly across Chat, Notes, Calendar, Docs and Sheets.
• Complex interactions such as group messaging, editing, scheduling and collaboration feel fast and reliable.
• AI capabilities are integrated naturally into product workflows rather than added as separate chatbot experiences.
• Frontend architecture remains fast, maintainable and reusable as ActAI expands into new applications and workflows.

Tech Stack

• TypeScript
• React.js / Next.js
• HTML / CSS
• WebSockets / streaming APIs
• Node.js
• REST / GraphQL APIs

How We Work

The best products today in the world were built by small, world-class teams. We are a high talent density and hands-on team. We make decisions collectively and move at rapid speed, striking a balance between shipping high-quality work and learning.

Joining our team requires the ability to bring structure, exercise judgment and execute independently. Our goal is to put in the hands of our users a truly magical product.

Interview Process

If there appears to be a fit, we'll reach out to schedule 3, but no more than 4 interviews.

Applications are evaluated by our technical team members. Interviews will be conducted via virtual meetings and/or onsite.

We value transparency and efficiency, so expect a prompt decision. If you've demonstrated the exceptional skills and mindset we're looking for, we'll extend an offer to join us and help bring practical AI benefits to billions of users globally.