Senior Software Engineer

Company Introduction

NextDay AI is a privately held company specializing in applying artificial intelligence (AI) engineering and creative innovation in B2C entertainment products. Our mission is to leverage the power of Large Language Models (LLM) and generative AI (Gen AI) to create innovative consumer products that push the boundaries of entertainment and companionship. With over 35 millions+ messages per day and millions of monthly visitors, our products are revolutionizing the way people interact with AI.

This is a unique opportunity to participate and make a real difference in a company actively working to shape the future of AI applications for consumers.

Job Description

We are looking for a Senior Software Engineer who thinks like an engineer first and writes code second. You will build new features for AI-powered role-playing chat products: several brands, web and mobile applications, one shared codebase, and tens of millions of active users. You work fullstack and move between React, React Native, Node.js, and AWS based on what the feature needs.

You own your features. You take a feature from an idea to production, decide how it should be built, and stay responsible for how it works after release. You also have real authority: you can change the technical approach, challenge requirements, and propose product changes when you see a better option for the user. We expect you to use that authority and to explain your decisions.

Code agents are part of your daily work. You use them to move fast, but you lead them: you give the agent a clear specification and the right context, you guide it in small steps, and you review everything it produces. You make the decisions.

What You Will Do

• Own a complete feature from requirements to release, including its technical design, edge cases, error handling, and integration with existing parts.
• Create technical designs and explain them clearly to engineers and to non-technical people.
• Review Pull Requests from other engineers and from your code agents. Check how the code meets our standards and how easy it will be to maintain.
• Write a clear technical specification and spec prompt for execution in small controlled steps.
• Work with the Product team to collect requirements. Find gaps in the ticket, suggest changes, and improve the user experience instead of only building what is written.
• Plan your work around sprint priorities, estimate realistically.
• Mentor Middle Software Engineers, and write documentation.

What We Are Looking For

• Five or more years of professional engineering experience, with a track record of shipping production software used at scale.
• Solid engineering foundations that you apply without reminders: Keep It Simple, Don't Repeat Yourself, Single Responsibility, Separation of Concerns, Functional Programming.
• System design skills: client and server split, stateless services, caching, and a single source of truth for each piece of data. Concurrency state solving.
• Experience with unit, integration, and end-to-end testing.
• Deep knowledge of React and its ecosystem, including state management, list virtualization, and data persistence.
• Strong Node.js knowledge and the ability to design a clear API.
• Advanced TypeScript.
• Experience with React Native, or strong motivation to learn it quickly.
• Working knowledge of document-oriented databases such as DynamoDB.
• Practical experience with AWS: S3, Elastic Compute Cloud, SQS, load balancers, and CloudWatch.
• Daily, deliberate use of code agents. You know how to design a prompt, how to feed the right context, and when a task is too complex or too specific to trust the output.
• Clear communication. You can defend a technical decision in front of engineers and explain the same decision to a Product Owner.

Why Join Us?

• Real 100% remote work. We do not have physical offices to visit "once per week".
• Flexible time. Manage your own schedule, because we look for teamwork and results, not hours.
• Unlimited vacation policy.
• Competitive salary and benefits package.
• A dynamic and supportive work environment.