Currently, ManTech is seeking a motivated, career and customer-oriented **Principal Software Engineer** to join our team in the **Reston or Chantilly, VA** location. This is an onsite position. The successful candidate will be dedicated full-time to development and enhancement support for existing software and systems solutions and the development of new solutions as required. **Responsibilities include but are not limited to:** + Designing, developing, programming, and modifying software, systems, applications, and tools, both existing and new in the future + Analyzing software and integration requirements and working with team members to determine development and implementation plans + Correcting errors by making the appropriate changes and then re-checking the program to ensure the desired result was produced + Developing solutions and maintaining support for external data sources and users + Building web services, APIs, and other solutions to interface with third-party systems to synchronize data + Conducting testing of software to be sure it will produce the desired results and that instructions are correct + Organizing and maintaining documentation of developed software and subsequent revisions, so others are able to understand the program + Collaborating with teammates, third-parties, vendors, and users to develop new requirements and solutions **Minimum Qualifications:** + 15+ years of relevant software engineering experience + Bachelor’s degree in a relevant area or five (5) additional years of relevant project management experience in lieu of a degree + Strong programming/development skills and hands-on engineering experience (Java & JDK 17+ and/or Javascript/Typescript) + Strong experience with REST APIs and standard software engineering tools such as Jira, Git, Gradle/Maven and experience developing software in Linux environments + Strong experience with the full data lifecycle, from ingest through display + Strong experience using SonarQube for code quality testing **Preferred Qualifications:** + Experience with one or more of the following development technologies: Vue.js, Vite, microservices, Bash, wireframes, UX patterns, Websockets, Groovy/Grails + Experience with one or more of the following test technologies: Junit5, AssertJ, Mockito, Postman, Vitest, Eslint + Experience with one or more of the following infrastructure/database technologies: MongoDB, Elasticsearch, PostgreSQL, RabbitMQ, Consul, Vault, Nomad, RHEL9 + Experience with Cloud technologies and developing in Cloud environments + Ability and willingness to travel overseas if required **Clearance Requirements:** + Must possess an active Secret **Physical Requirements:** + Must be able to be in a stationary position more than 50% of the time + Must be able to communicate, converse, and exchange information with peers and senior personnel + Constantly operates a computer and other office productivity machinery, such as a computer + The person in this position frequently communicates with co-workers, management, and customers, which may involve delivering presentations. Must be able to exchange accurate information in these situations + The person in this position needs to occasionally move about inside the office to access file cabinets, office machinery, etc.