Sr. Back-end Developer

Visma; Rotterdam; On-site; EUR 70,000 - 100,000; Full time

Job summary

Yuki is seeking two Senior Back-end Developers to join our development teams (AO Ops and Platform). You will help own, build, and scale the core financial engine and infrastructure that powers our SaaS accounting platform.

As a senior, you will mentor juniors, guide code quality, and collaborate with cross-functional teams to ship robust features. Strong .NET, MSSQL, REST, and DevOps experience required; cloud and NoSQL exposure are a plus.

Qualifications

• 4+ years of backend development with .NET technologies (VB.NET/C#).
• Experience coaching and mentoring junior developers.
• Strong MSSQL relational database experience and API development.

Responsibilities

• Participate in full application lifecycle, focus on optimization and refactoring.
• Improve performance of critical applications for speed and scalability.
• Build readable, maintainable, and performant code using best practices.
• Mentor juniors, conduct peer reviews, and share knowledge across the team.
• Collaborate with cross-functional stakeholders to deliver features.

Skills

NET/.NET Core

C#/VB.NET

SQL MSSQL

API Development

RESTful Services

Azure DevOps

Mentoring

Agile Scrum

Tools

GitHub

NoSQL (MongoDB/DynamoDB)

AWS

Vue.js

Angular

Job description

Yuki & The Yuki Way

Hi there, welcome to Yuki! As a vibrant, international IT scale-up, we support accountants, businesses, and entrepreneurs in handling their accounting more efficient and simple, and thus make it more enjoyable! And to make that possible? Well, we're looking for kick‑ass colleagues to complete our ambitious, cheerful, and lively team of top professionals!

Yuki is one of the leading innovators in the domain of accounting and financial administration. We are rapidly growing and, as a product driven organization, it makes us proud that our business-critical SaaS solution is already used by over 140.000 companies and hundreds of accountancy firms across The Netherlands. We need you to own, build, and scale the core financial engine and infrastructure that form the very heartbeat of our accounting platform!

Your Role at Yuki

We are currently looking for two Senior Back-end Developers to join our development organization. We have two distinct high-impact teams available: Team AO Ops and Team Platform.

Team AO Ops

Team AO Ops is responsible for the bedrock of our software: the core accounting domain. The team's mission is to ensure that Yuki's financial engine remains rock-solid, highly performant, and exceeds our users' expectations every single day.

Team Platform

Team Platform focuses entirely on system-technical excellence and internal-tooling rather than client-facing features. The team is responsible for internal tooling/processes and integration with other Visma solutions.

(During the intake conversation, we will explain both team dynamics in detail to see which challenge fits your expertise best!)

What you get to do (across both teams)

Participate in the entire application lifecycle, focusing on optimizing and refactoring the existing codebases, enhancing the performance of critical applications for maximum speed and scalability, and building readable, maintainable, and performant code using the best software practices.

Furthermore, as a senior developer you will be a reference to the team, you will guide junior developers and help implement new features and functionalities into our product(e.g. API's, data interfaces with external parties, etcetera).

• Feature Development & Integration: Work on implementing new features, APIs, system integrations, and data interfaces (with external parties or Visma solutions), ensuring they are efficient, robust, and aligned with user/system needs.
• Code Optimization: Optimize and refactor existing codebases, focusing on improving performance, readability, and maintainability.
• Code Development: Build readable, maintainable, and performant code by applying best software practices and industry standards.
• Performance Enhancement: Optimize business-critical applications for maximum speed and scalability under heavy system load.
• Mentoring and Coaching: Provide guidance, peer reviews, and support to less experienced team members, helping them improve their technical skills and grow professionally.
• Team Collaboration: Work closely with cross‑functional team members and technical stakeholders, fostering effective communication to achieve project goals.

What are we looking for

• At least 4 years of experience as a back-end developer using .NET Technologies (VB.NET/C#)
• Experience with coaching and mentoring junior developers (e.g., peer reviewing, sharing best practices etc.)
• Strong experience with relational database engines (MSSQL);
• Experience with API development HTTP, REST and .NET Web API;
• Experience in Agile methodologies (Scrum);
• Experience with Azure DevOps and/or Github;
• Autonomy, analytical mindset, and strong organizational skills.

Big plusses if

• Familiarity with AWS S3 / SNS / SQS
• Some experience with JavaScript frameworks (e.g., Vue, Prototype, Angular)
• Experience in performance-critical applications
• Familiarity with OCR systems and Machine Learning (ML)
• Experience with ASP.NET
• Familiarity with NoSQL databases (e.g., MongoDB, DynamoDB)

Very Important: What's in It for You

At Yuki, we believe in empowering our team so they can empower our users. Here's what