Senior Backend Engineer - Rust

The Modern Milkman; City of Westminster; On-site; GBP 60,000 - 80,000; Full time

Job summary

A forward-thinking delivery startup based in the UK is seeking a Senior Rust Engineer to enhance its technology platform. The role requires a balance of shipping features and ensuring code stability while migrating legacy systems from C# to Rust. Candidates should be experienced with Rust and possess a pragmatic approach to problem-solving. Benefits include generous holidays, share options, and various wellness budgets. This position is ideal for engineers passionate about sustainable technology and quality code.

Benefits

25 days holiday

EMI Share Options

Up to 6% matched company pension

Employee discount off products

Enhanced parental leave

Cycle to work scheme

£300 working from home set up

£300 L&D budget

Health and Well Being budget

Volunteering days

Company events

Qualifications

• Senior engineer with expertise in Rust and modular system design.
• Comfortable with both Rust and legacy C# migration.
• Strong documentation and code quality practices.

Responsibilities

• Develop and maintain performant Rust services.
• Migrate critical logic from C# to Rust.
• Collaborate with teams to solve domain problems.

Skills

Rust programming

Understanding of concurrency

Performance optimization

C# familiarity

Job description

Modern Milkman isn't just another delivery startup. We're a Certified B Corporation designing the milk round for the modern world; reconnecting households with local suppliers while cutting packaging waste and emissions from the supply chain. Our technology platform is the engine behind that mission. Every Rust module, API, and database migration helps power a real-world system that delivers reusable packaging, reduces waste, and makes sustainable living effortless for over one hundred thousand of customers across the UK and US. We move fast, build with intent, and balance environmental impact with engineering excellence. Joining the team means shaping software that has both purpose and technical depth.

Performance Expectations

• Service quality: measurable improvements in availability, latency, and error rates across customer and operations journeys.
• Migration delivery: completion of defined C#-to-Rust migrations with no functional regression and clear performance gains.
• Engineering standards: creation and ongoing maintenance of clear, documented standards for Rust development, testing, and observability.
• Team discipline: fostering a culture of diligence, code quality, and operational accountability within the Customer Team and beyond.

Responsibilities

• You’ll be expected to balance shipping features with raising the bar; ensuring every line of code contributes to stability, clarity, and long‑term maintainability.
• Design, build, and maintain performant Rust services within our modular monolith, using Actix‑Web and explicit SQL.
• Migrate critical business logic from legacy C# systems into Rust, ensuring accuracy, performance, and observability.
• Identify, prioritise, and deliver improvements to reliability, latency, and error rates across customer and operations workflows.
• Maintain disciplined testing, code review, and documentation practices that set the standard for the wider team.
• Define and uphold engineering conventions; including module structure, observability, and deployment patterns, and ensure they are explained and adopted consistently.
• Collaborate with other teams (Product, Operations, Data) to translate domain problems into robust technical solutions.
• Support architecture and platform evolution, contributing to design discussions and long‑term technical decisions.
• Participate in incident reviews and post‑mortems, ensuring lessons are codified into future development.
• Offer technical guidance to peers when needed, by example rather than title.

What you’ll bring

• You're a senior engineer who prefers clarity over ceremony. You care about correctness, reliability, and the integrity of the systems you build. You can explain technical reasoning clearly to both engineers and non‑technical peers, and you don’t lose patience when the details matter.
• You're deeply experienced in Rust, comfortable designing large, modular systems and reasoning about concurrency, performance, and correctness. You may not be a C# expert, but you’re pragmatic enough to dive into it, extract what’s valuable, and migrate it cleanly into Rust when needed.
• You balance speed with precision, document as you go, and leave systems cleaner than you found them. You’re comfortable owning a problem end‑to‑end; from design and data model to deployment and monitoring. You like Rust because it enforces discipline, and you value that same discipline in your teams.
• If you see a broken abstraction, you fix it. If you see a messy process, you streamline it. You understand that the product and the system succeed together, not in isolation.

Benefits

• 25 days holiday, 8 bank holidays (5 flexible ones). Plus, your birthday off too!
• EMI Share Options
• Up to 6% matched company pension.
• Access to thanksBen, for a range of core & flexible benefits
• Employee discount off Modern Milkman products
• Enhanced parental leave & pay
• Life Insurance
• Cycle to work scheme & Octopus EV salary sacrifice
• In‑person company events
• £300 working from home set up
• £300 L&D budget per annum
• £300 Health and Well Being budget
• Endless samples of our stock – Seriously, our category managers have us taste‑testing food and drinks all the time!
• Up to 4 weeks working abroad
• 2x volunteering days and team volunteering days
• Loads of company clubs to join, from book clubs (Page Churners), Running, cycling and swimming (Trotters and Plodders), 5 aside Football (Modern Milkman FC) and any other pun‑related clubs you can think of.

Interview Process

• Screening Call
• Hiring manager call
• Technical interview inc ways of working
• Final Intro with Product Director / CTO

Due to the high volume of applications, it might take us a little longer to get back to you. Most feedback will be shared via email, and we make every effort to provide specific and constructive insights whenever possible. We strongly encourage candidates of all different backgrounds and identities to apply. We believe that our team is stronger with a variety of perspectives.