Senior/Lead Software Engineer - Backend AI Agents

About Us

At Sales Marker, our mission is to create a world where all people and companies can challenge themselves beyond existing boundaries. We are one of the fastest-growing startups in Japan—scaling at more than twice the pace of typical unicorns. Our flagship product, Sales Marker, empowers sales teams to achieve 3 times greater efficiency. In just two years since launch, we’ve achieved 2,000% growth, and today our year-over-year business growth stands at 270%—and this is only the beginning.

Backed by strong financial growth, we’re expanding into a bold portfolio of new products, empowering businesses to grow from every angle: Sales, Marketing, Recruiting, AI agents and so on.

The Team

Our co-founders come from leading global companies and were recognized on the Forbes 30 Under 30 Asia List (2023).

Our Product & Engineering team is proudly global, with members from 24+ countries and backgrounds at top tech companies such as Google, Microsoft, Indeed, Mercari, LINE, Yahoo, and SmartNews etc.

At Sales Marker, you’ll join a global, ambitious, and fast-moving team where your ideas truly shape the future. We’re building an engineering culture around:

• Customer Obsession – solving real problems and exceeding expectations
• Ownership – taking responsibility end to end, across roles and functions
• 10x – aiming for bold impact, moving fast, and disrupting old standards

The Role

As a strategic role reporting directly to the CTO, you will be at the forefront of driving our AI Agent development. This position goes beyond a typical engineering role, involving significant engagement in strategic decision-making and the direction of our products. You will take a leadership role in building the next generation of AI Agents, driving innovation through collaboration with internal and external stakeholders. You will also lead large teams, leveraging the latest AI technologies to develop and operate next-generation enterprise solutions.

• Provide technical leadership for AI Agent development projects.
• Design and select system architectures.
• Provide technical support and conduct code reviews for team members (senior and junior).
• Coordinate technically with external stakeholders (Product, UX, Research, etc.).
• Evaluate cutting-edge LLM and agent technologies and formulate adoption strategies.

What We're Looking For

Required

• Have meaningful experience with building (and rebuilding) production systems to deliver new product capabilities and to handle increasing scale
• Care deeply about the end user experience and take pride in building products to delight customers
• Experience leading development teams or managing projects with multiple members.
• Large Language Model Integration: Experience working with LLM APIs (e.g., OpenAI, Anthropic) and integrating them into agent workflows for natural-language understanding and generation
• Agent Solution Design: Ability to design and build deployable AI agent solutions and best-practice templates for internal and external stakeholders
• Cloud Platform Expertise: Hands-on experience with AWS, GCP, or Azure to deploy, scale, and secure AI services in production
• Database Design & Optimization: Expertise in designing scalable database schemas, indexing strategies, and query optimization for high-performance applications
• Understanding and practical experience with Model Context Protocol (MCP).
• Business-level English proficiency.

Nice to Haves

• Agent Orchestration Frameworks: Familiarity with platforms like LangChain, Rasa, or Restack to build, evaluate, and iterate on AI agent workflows
• Benchmarking & Evaluation: Experience with tools and methodologies to measure agent accuracy, reliability, and on-brand performance
• Experience promoting projects in startups or R&D departments.
• Experience with technical presentations and public speaking, both internally and externally.

Our Tech Stack

Front-end

• TypeScript, React, NextJS;
• Testing: Storybook, jest, playwright;
• Hosting: Amplify;
• Feature flag: Unleash;

Server Side/Back-End

• Infrastructure: AWS, EKS, ElasticBeanstalk;
• DB: Aurora, ElasticSearch, Redis;
• Languages: Go, Typescript;
• Analysis environment: Athena, Superset;
• Monitoring: DataDog;
• Others: AWS Lambda, AWS Batch, AWS API Gateway, AWS Glue, AWS S3;

Why Us?

• One of the fastest growing Saas startup in Japan with strong financial growth.
• Innovative new product development and opportunity to build things from scratch.
• Plenty of leadership and career development opportunities.
• Hybrid work environment & full flexible work schedules.
• Global team and English speaking environment.
• Great benefits & perks packages such as Resort Worx, Purchasing Books, Free Weekly Lunch, Offsites, etc.

Working Style

Hybrid Work

• We follow a hybrid work style, combining both office and remote work. Recommended in-office days vary by role. Even when working remotely, we maintain smooth collaboration and communication through tools like Zoom, Google Meet, and Gather.

Flex Work

• You can customize your working hours to suit your day. For business and client-facing teams, schedules are often arranged around client meetings.

Global Environment

• With team members from over 20 countries, we bring together diverse perspectives and ideas, driving projects forward across languages and cultures in an environment where English and Japanese blend naturally into daily communication.