Back-End Developer (Node.js / Microsoft SQL Server)

Flexi-Software; Atlanta (GA); Hybrid; USD 110,000 - 160,000; Full time

Benefits offered by this job

Health and dental insurance

401(k) plan with company participation

Paid holidays and paid time off

Vision discount plan

Job summary

Flexi Software, a long‑standing enterprise software company, seeks a backend developer to build the API layer in Node.js on SQL Server. The role focuses on 70% API and service development and 30% database work, with deep T‑SQL knowledge and multi‑tenant considerations.

You will work in a small team in our Atlanta office on a hybrid schedule. We value experience with NestJS/Express, TypeScript, and a solid track record in high‑volume OLTP systems, with ownership over design decisions and

Qualifications

• 4–7 years of professional back-end development experience.
• Strong Node.js skills and experience building REST APIs with NestJS or Express.
• Professional TypeScript experience; fluent with typed JavaScript.
• Deep MS SQL Server / T-SQL expertise including indexing and query tuning.
• Experience with concurrency in high-volume OLTP systems and relational schemas.
• Ability to own tasks end-to-end with minimal supervision.

Responsibilities

• Build API services in TypeScript on Node.js; design, develop, test, and document RESTful services.
• Work across the data boundary; write and tune T-SQL, evolve schemas, and decide if logic belongs in API or DB.
• Read legacy code and translate it into the new architecture while preserving accounting behavior.
• Profile and optimize queries, indexes, and endpoints for concurrency and large data volumes.
• Implement multi-tenancy and support both Azure SQL Database and on-premises SQL Server.
• Contribute to architecture; participate in design discussions and own tasks through to completion.
• Write unit and integration tests and prepare technical documentation.

Skills

Node.js

TypeScript

REST APIs

API design

Concurrency in OLTP

Relational database design

Software architecture

Problem solving

Education

Bachelor's degree in Computer Science or related field

Tools

Microsoft SQL Server / T-SQL

NestJS or Express

Git

Azure (Azure SQL Database)

Job description

Description

About Flexi

Flexi Software is a 30+ year-old enterprise software company building commercial accounting applications for both cloud and on-premises deployment. Our customers run their financial operations on our software — closing their books, reporting to regulators, and answering to auditors with it. That sets a high bar for correctness, and it is the reason our engineers care as much about the data layer as the code that sits on top of it.

We are now building the next generation of that platform. This is a re-platforming effort, not a science project: the accounting logic is proven, and the customers are already live, but the technology underneath it is roughly twenty years old and increasingly expensive to support. We are rebuilding it as a modern multi-tenant SaaS solution on Azure while continuing to support customers who deploy on-premises.

This role is one of the core engineering hires for that effort, based in our Atlanta office.

The Role

You will build the application API layer in Node.js on top of Microsoft SQL Server. In practice, the work runs roughly 70% API and service development, 30% database work — but the database 30% is what makes the other 70% possible. A great deal of Flexi's accounting logic lives in T SQL today, and you will be the person who can read it, reason about it, decide what belongs in the API and what stays in the database, and make both sides fast.

This is not a role where you hand SQL off to someone else. We are looking for a back-end developer who is genuinely strong in SQL Server — someone who reads an execution plan without flinching, knows why a query went sideways after a schema change, and has opinions about indexing that they can defend.

You will report to the engineering lead and work on a small, dedicated team of fewer than ten engineers. Small team, real ownership: the design decisions you make will be visible in the product and in the codebase for years.

What You'll Do

• Build API services — design, develop, test, and document RESTful services in TypeScript on Node.js (NestJS or Express).
• Work across the data boundary — write and tune T-SQL, design and evolve schemas, and make deliberate case-by-case calls about whether business logic belongs in a stored procedure or in the service layer.
• Carry legacy logic forward — read and understand existing legacy database code, and translate it into the new architecture without losing the accounting behavior our customers depend on.
• Make it fast under real load — profile and optimize queries, indexes and API endpoints for concurrency and large data volumes; diagnose performance problems from execution plans and query statistics.
• Build for multi-tenancy — implement tenant isolation, data partitioning and access patterns that hold up as the tenant count grows.
• Support both deployment models — write code that works against Azure SQL Database in our cloud and Microsoft SQL Server in customer on-premises installations, and account for the differences between them.
• Contribute to architecture — participate in design discussions for new functionality; on a team this size, mid-level engineers are expected to have a voice in the design, not just an assignment.
• Fix what breaks — investigate and resolve defects surfaced through QA and customer support, including issues that only appear at customer data volumes.
• Write the tests and the docs — unit and integration tests for the code you ship, and technical documentation your teammates can actually use.

Requirements

What We're Looking For

• 4–7 years of professional back-end development experience.
• Strong Node.js skills, with production experience building REST APIs — NestJS, Express, or comparable.
• Professional TypeScript experience. We expect working fluency with typed JavaScript (TypeScript) rather than a willingness to learn it.
• Deep Microsoft SQL Server / T-SQL expertise: stored procedures, views, functions, triggers, transactions and isolation levels, indexing strategy, and query tuning from execution plans. SQL Server 2017 or newer.
• Practical experience with concurrency in a high-volume OLTP system: transaction isolation levels, locking and blocking, deadlock diagnosis, and row-versioning approaches such as snapshot isolation. In an accounting system, a lost update is not a performance problem; it is a financial error.
• Demonstrated ability to design and evolve relational schemas for transactional systems, including migrations against databases that are already in production.
• Experience troubleshooting performance problems in high-volume data environments.
• Solid grasp of API design fundamentals: versioning, authentication and authorization, error handling, and backward compatibility.
• Comfort with Git and modern development workflow — branching, code review, CI.
• Bachelor's degree in Computer Science, Engineering, or a related discipline, or equivalent practical experience.
• Clear written and verbal communication: accurate status updates, early flagging of risk, and the judgment to raise a problem before it becomes a deadline.
• Ability to own tasks through to completion without detailed supervision, and to estimate your own work realistically.

Preferred

• Experience in a professional environment using C# and the .NET stack.
• Multi-tenant SaaS architecture experience, particularly tenant isolation and data-partitioning approaches.
• Azure platform experience: Azure SQL Database, App Service, Azure DevOps.
• Background in accounting, ERP, or financial software, or in any domain where data correctness is non-negotiable.
• Experience with commercial software that ships to customers, as opposed to internal-only systems.
• The Atlassian tool suite — Jira, Confluence, and Loom.
• Reporting and analytics exposure — Microsoft Fabric, the umbrella Microsoft's data and analytics services are consolidating under, along with Power BI and Azure Synapse Analytics.

Why This Role Is Worth Your

Time Re-platforming a proven product is a specific kind of engineering problem, and a genuinely interesting one. You get the freedom of a modern stack with the discipline of real customers and real accounting requirements — no hand-waving about what the software has to do, because it already does it. You will learn the domain deeply, work on a team small enough that your decisions matter, and end up with the rare combination of strong API skills and strong database skills that makes a back-end developer hard to replace.

Location & Schedule

This is a hybrid position based in metro Atlanta, Georgia, with several days per week in our Atlanta office. Candidates must be local to the Atlanta market or willing to relocate before starting.

Compensation & Benefits

Compensation is competitive and commensurate with experience. Flexi provides excellent benefits including paid holidays and paid time off, a 401(k) plan with company participation, health and dental insurance, life and disability insurance, and a vision discount plan.

Flexi Software is an equal opportunity employer. M/F/V/H EEO