Senior Software Engineer (JavaScript, MongoDB)

Title : Senior Software EngineerHybrid2 to 3 Months contract ( Possible for Extension)Location : Fremont, CAOverviewOur client is seeking an experienced Senior Software Engineer in Fremont, CA for an onsite contract opportunity.The Senior Software Engineer will rapidly bootstrap and deliver a scalable MongoDB application within an approximately 6-week deliverable timeline, including initial wireframing, frontend components, backend services, database structure, and API connections.You will develop, enhance, and support a complex software application. This role requires a highly experienced full-stack engineer who can think critically through abstract technical problems, independently own solutions, and lead projects from definition through completion.The ideal candidate brings deep expertise in JavaScript, TypeScript, MongoDB, ElectronJS, React, Node.js, REST APIs, and modern frontend development , along with strong software engineering, code review, and project leadership experience.What You'll DoWork effectively in a fast-paced, startup-style environment, independently turning high-level requirements into functional, scalable solutions.Analyze, develop, and modify complex software applications and information systems.Lead software projects by defining requirements, specifications, milestones, and tasks.Own technical solutions from initial problem definition through successful completion.Design and develop frontend and backend application functionality.Build and maintain RESTful APIs and server-side applications.Develop and manage SQL and NoSQL databases (MongoDB).Investigate application and system issues, isolate root causes, and implement resolutions.Improve application performance by identifying technical trends, developing specifications, and recommending solutions.Support business leadership in evaluating software and hardware requirements, options, risks, costs, and business impact.Track project activity, resolve issues, publish progress updates, and recommend corrective actions when needed.Perform code reviews and provide constructive technical feedback.Manage source-control activities including branching, merges, and conflict resolution.Mentor colleagues on software engineering standards and best practices.Work collaboratively across technical and business teams.What You Bring to the Role ( Required Experience )10+ years of JavaScript experience required.7+ years of MongoDB experience required.Hands-on MERN stack experience, including MongoDB, Express.js, React, and Node.js.Experience with ElectronJS is strongly preferred.Demonstrated ability to solve complex and abstract technical problems.Experience breaking projects into milestones and tasks and leading them through completion.Strong understanding of the software development lifecycle (SDLC).Experience with code reviews, branch management, merge conflict resolution.Software development best practices.Strong communication and organizational skills.Frontend TechnologiesHTMLCSSJavaScriptTypeScriptReact.js or similar frontend libraries.CSS frameworks such as Tailwind CSS.UI frameworks such as Ant Design and shadcn.Global state-management tools such as Redux and React Context API.Backend TechnologiesNode.js or comparable server-side technologiesRESTful API developmentServer-side frameworks such as Express.jsSQL and NoSQL database development and administrationSQLiteMySQLMongoDBEducationDegree in Information Technology or related field.