Senior Software Engineer / Tech Lead (AI)

About Threecolts

Threecolts is a software suite built for consumer brands, helping them recover revenue, operate more efficiently and grow across major retailers and marketplaces.
Our largest business, Margin Pro, helps brands recover money owed to them by retailers and marketplaces such as Amazon, Walmart and Target by managing disputes on their behalf. Alongside this, we’re building and scaling newer products, including AI Operator and Retail 365, while continuing to grow our portfolio of subscription products across our customer base.

Who We Are 

We’re a global team of 340 people across 33 teams, having grown through 24 acquisitions. We operate with a flat structure, giving people real ownership and the ability to move quickly. AI is embedded in how we work across the business, helping us increase speed, improve quality and operate at scale.

About the Role
We're looking for a hands-on Senior Software Engineer / Tech Lead to join ExportYourStore, one of the products within the Threecolts portfolio.
ExportYourStore is a SaaS platform used by around 1,200 paying sellers to list, manage and synchronise products across marketplaces including Shopify, Amazon, eBay, Etsy, Walmart, Poshmark, Depop and Vinted.
We're a small, collaborative team of three developers and a product lead, with ambitious plans to make AI a core part of the platform.
This role sits at the intersection of backend engineering, AI development and technical leadership. You'll take ownership of building production-ready AI features, developing our Model Context Protocol (MCP) server and API infrastructure, and improving the underlying platform.
We're looking for someone who enjoys writing code, solving complex problems and shipping products that customers actually use. You'll have a real say in technical decisions, work closely with product and the GM, and help shape where we take the platform next.
This is a hands-on role, not a traditional people management position.

What You'll Do

• Design, develop and launch AI features using large language models (LLMs), including listing optimisation, product descriptions, pricing insights, translation and image enhancement.
• Build reliable AI workflows with a focus on output quality, performance, latency and cost.
• Evaluate and improve AI features based on real customer usage and measurable results.
• Design, build and maintain our MCP server and public API, enabling AI assistants and autonomous agents to interact with ExportYourStore.
• Develop secure, scalable integrations that allow AI agents to perform actions on behalf of sellers.
• Ensure APIs are reliable, well-documented and built for long-term scalability.
• Work hands-on across our existing technology stack, including .NET, C#, SQL Server, MongoDB and REST/GraphQL APIs.
• Build and maintain integrations with major e-commerce platforms and marketplaces.
• Improve platform performance, reliability and scalability as our product evolves.
• Take technical ownership and collaborate
• Own features from initial design through development, testing and production.
• Break complex projects into manageable stages and deliver improvements regularly.
• Work closely with developers, product and the GM to translate business priorities into technical solutions.
• Contribute to code reviews, technical discussions and knowledge sharing, supporting other engineers when needed.
• Communicate progress clearly, identify risks early and help keep delivery on track.

 About You

• 5+ years of software engineering experience, ideally building and maintaining production SaaS applications.
• Hands-on experience developing and shipping AI-powered features using LLM APIs such as OpenAI, Anthropic or similar. We're looking for real production experience, not just personal projects or prototypes.
• Strong understanding of LLM integration, including prompt engineering, function calling, structured outputs, evaluation and cost optimisation.
• Experience building an MCP server or similar AI agent/tool integration architecture.
• Strong backend engineering skills, with the ability to design scalable, reliable applications and APIs.
• Experience with .NET/C#, SQL Server or MongoDB is advantageous, but we're open to engineers with other backend stacks who can pick up new technologies quickly.
• Experience integrating third-party APIs, including OAuth, webhooks, rate limiting and data synchronisation.
• Comfortable taking technical ownership while remaining hands-on with development.
• A collaborative, pragmatic approach to engineering, with strong communication skills and a willingness to share knowledge.
• Good working English, comfortable collaborating with an international remote team.

Nice to have 

• Experience with AI agent frameworks, retrieval-augmented generation (RAG) or AI evaluation tools.
• Experience with e-commerce platforms, marketplace APIs or seller tools.
• Mobile development experience (iOS, Android or cross-platform).
• Experience building browser extensions.
• Experience working in a small, fast-moving SaaS team.

What Success Looks Like

Within your first six months:

• Our MCP server and public API are live, reliable and being used by real customers and AI assistants.
• You've launched at least two AI-powered features that demonstrate measurable improvements in customer adoption or add-on usage.
• You're consistently delivering high-quality features in manageable stages, with clear communication and predictable timelines.
• You've helped improve how the team builds, tests and ships AI-powered functionality.
• You're making a visible impact on the product's growth, technical direction and customer experience.

Note : - This is a Contractor Role 
Location: Remote – Eastern Europe.

Compensation, Perks & Benefits

• Salary: $5,500 a month.
• Fully remote working