Sr. Software Engineer

essentialsoftwareinc; Rockville (MD); Hybrid; USD 115,000 - 160,000; Full time

Benefits offered by this job

Health care

401(k) retirement plan

Professional development

Paid time off

Job summary

Essential Software Inc. in Rockville, MD, seeks a Sr. Software Engineer to design and deliver front-end solutions within federal project contexts.

You will lead React.js applications, integrate APIs, and mentor juniors, while aligning with governance and accessibility standards. The role is hybrid with periodic travel to client sites in the DC area.

Qualifications

• Bachelor's degree in CS, Web Development, or related field.
• At least 5 years of relevant experience.
• Expertise in React.js with hooks, context, Redux or equivalent.
• Proficiency in Node.js including middleware, API integrations, and tooling.
• Experience with HTML5, CSS3, JavaScript (ES6+), and WCAG 2.1 accessibility.
• Familiarity with Webpack, Vite, or similar build tools.
• Experience with Git and CI/CD pipelines.
• AWS AI Practitioner certification (or ability to obtain).
• Excellent verbal and written communication with customers and stakeholders.
• Strong prioritization and multitasking abilities.
• Interpersonal and collaboration skills in cross-functional teams.
• Ability to work in a complex government-related environment.

Responsibilities

• Collaborate with UX designers, back-end engineers, and product owners to deliver high-quality front-end solutions.
• Architect, develop, and maintain scalable React.js applications and component libraries used across platforms.
• Build and integrate RESTful and GraphQL APIs using Node.js for seamless front-end and back-end communication.
• Create and manage technical documentation including component docs and front-end architecture guides.
• Write clear technical design documents for multi-developer projects or complex components.
• Work with business users and stakeholders to develop acceptance tests ensuring accessibility and requirements.
• Monitor front-end performance, identify bottlenecks, and optimize for speed and reliability.
• Integrate existing software and design systems into new environments.
• Lead process improvements, coding standards, and documentation practices.

Skills

React.js

Node.js

HTML5/CSS3/JavaScript

Redux or state management

RESTful APIs

GraphQL APIs

Web performance optimization

Git / CI-CD

AWS AI Practitioner

Communication skills

Government project experience

Education

Bachelor's degree in Computer Science or related field

Tools

Webpack

Vite

Git

CI/CD pipelines

REST API tooling

GraphQL tooling

Job description

Sr. Software Engineer

About the Role

ESI provides direct support to the Frederick National Lab (FNL) and its clients at the National Cancer Institute (NCI), aiding their mission to accelerate the prevention and treatment of cancer. FNL's support of NCI includes the management and execution of IT projects.

The organization supports several high-priority programs focused on advancing research through modern data infrastructure. These programs provide secure, cloud-based environments that accelerate discovery byfacilitatingdata submission, sharing, access, interoperability, and cost-effective analysis at scale. The data ecosystems are dynamic and evolving infrastructures that bring together data from various collections generated or held at institutions across the country and worldwide, ensuring quality and consistency for the broader research community.

The systems include:

• Enhanced cloud-computing platforms.

• Services thatlinkdisparate information, including clinical, image, and molecular data.

• Standards and tools so that data are interoperable.

• Essential underlying data science infrastructure, methods, and portals for the Cancer Data Ecosystem.

• Sustainable data governance to ensure long-term health of the Ecosystem.

What You'll Do

• Collaborate with UX designers, back-end engineers, and product owners to deliver high-quality front-end solutions that meet user needs and follow established design systems and development standards.

• Architect, develop, andmaintainscalable React.js applications andcomponentlibraries used across NCI platforms.

• Build and integrate RESTful andGraphQLAPIs using Node.js, ensuring seamless communication between front end interfaces and back-end services.

• Create and manage technical documentation, includingcomponentdocumentation and front-end architecture guides.

• Write clear technical design documents independently for projects involving multiple developers or for critical, complex front-end components.

• Work with business users and stakeholders to develop and implement acceptance tests, ensuring products meet customer requirements and accessibility standards.

• Monitor front end application performance,identifybottlenecks, and implement optimizations for speed and reliability.

• Integrate existing software and design systems into new or modified environments.

• Implement recommendations for improving front end development processes, coding standards, and documentation practices.

• Serve as a trusted reviewer for complex or critical front-end code changes within the team, setting an example for code quality, extensibility, and testing.

• Lead projects involving multiple contributors (or independently drive a complex project): set milestones, break work into manageable tasks, delegate when needed, and adjust timelines as complexityemerges.

• Actively engage in process improvement and Agile/Scrum ceremonies.

• Integrate AI-assisted development tools into workflows responsibly and help define safe patterns for their use.

• Proactively mentor junior teammates through code reviews, pairing sessions, and knowledge sharing.

• Lead technical presentations (e.g., brown bags, design/analysis reviews) and regularly communicate project progress, risks, and technical designs to stakeholders.

What You'll Bring

• Possession of a bachelor's degree from an accredited college/university according to the Council for Higher Education Accreditation (CHEA) in Computer Science, Web Development, or a related field.

• At least 5 years of experience in the above roles and responsibilities.

• Demonstratedexpertisein React.js, including hooks, context, state management (Redux or equivalent), and component-driven architecture.

• Proficiencyin Node.js, including building middleware, API integrations, and development tooling.

• Experience with HTML5, CSS3, JavaScript (ES6+), and responsive/accessible design principles (WCAG 2.1).

• Familiarity with front end build tools such as Webpack, Vite, or similar.

• Experience with version control systems (Git) and CI/CD pipelines.

• AWS AI Practitioner certification (or ability to obtain).

• Excellent verbal and written communication skills, including experience working directly with customers and stakeholders to translate requirements into user-centered designs.

• Strong ability to prioritize, manage, and communicate the status of multiple concurrent tasks.

• Exceptional interpersonal and collaboration skills, with experience working in cross-functional team environments.

• Ability to work effectively in a complex, fast-paced environment, including with government stakeholders and in adherence to government practices and processes.

Preferred Qualifications

• Experience with AWS services (S3, CloudFront, Amplify, or similar) and cloud-hosted front-end deployments.

• Any AWS Associate certification (alternate path if AWS AI Practitioner is obtained afterhire).

• Familiarity with data visualization libraries (D3.js, Recharts, or similar) in the context of scientific or research platforms.

• Prior experience working on federal or government-sponsored IT programs.

About Essential Software Inc. (ESI)

In a time when federal agencies rely on novel technology solutions, ESI stands as a trusted partner. We have built our success on our commitment to technology, teamwork, and trust. At ESI, we acknowledge and celebrate our dedicated, diverse staff, who consistently strive for and achieve excellence.

ESI offers a robust benefits package that includes health care, paid time off, 401(k) retirement savings, professional development, and more.

Equal Opportunity Employer:

ESI is an Equal Opportunity Employer (EOE). We are committed to creating an inclusive environment for all employees, includingequitablehiring and promotion practices, and ongoing learning that supports belongingforevery team member.

Work Authorization Notice:

Candidates must be legally authorized to work in the United States at the time of hire. ESI is unable to provide employment visa sponsorship for this position now or in the future. Because this role is performed in support of government contract work and does not allow ESI to provide the level of direct employer oversight and training administration required for certain temporary work authorization categories, ESI cannot support those employer-specific training obligations for this position.

Work Location:

Hybrid;periodic travel (1–4 days a month) to our client office in Rockville, MD 20850 for meetings and/or collaboration sessions isrequired. You must live in the Washington, D.C., Maryland or Virginia area. This is not a fully remote position.

Job Type: Full-Time

Salary:$115,000–$160,000 per year, depending on skills and experience.

Essential Software Inc. provides equal employment opportunities to all employees and applicants for employment and prohibits discrimination and harassment of any type, without regard to race, color, religion, age, sex, national origin, disability status, genetics, protected veteran status, sexual orientation, gender identity or expression, or any other characteristic protected by federal, state or local laws. This policy applies to all terms and conditions of employment, including recruiting, hiring, placement, promotion, termination, layoff, recall, transfer, leaves of absence, compensation, and training.