When it comes to mobile app development companies in the USA, there are several top players in the industry. New Jersey (NJ) is home to numerous reputable companies that excel in mobile app development. Here is a list of some of the top mobile app development companies in NJ, being recognized as one of the best:

1. Appinventiv: Appinventiv is a leading mobile app development company in USA and with a strong presence in New Jersey. They have an impressive track record of delivering innovative and high-quality mobile applications for various industries. Appinventiv is known for its customer-centric approach, deep technical expertise, and commitment to delivering exceptional user experiences.
2. Fingent: Fingent is a well-established mobile app development company based in New Jersey. They specialize in developing custom mobile applications for businesses across different sectors. With a team of skilled developers and a focus on creating intuitive and user-friendly apps, Fingent has earned a reputation for delivering reliable and feature-rich solutions.
3. eMobiStudio: eMobiStudio is a New Jersey-based mobile app development company that offers a wide range of services, including app development, UI/UX design, and quality assurance. They have worked with both startups and established enterprises, providing them with scalable and robust mobile solutions tailored to their specific needs.
4. TechAhead: TechAhead is a mobile app development company with offices in New Jersey and California. They have a talented team of developers and designers who are experienced in creating mobile apps for various platforms. TechAhead focuses on delivering customized solutions that align with clients' business objectives.
5. WillowTree: Although based in Charlottesville, Virginia, WillowTree has a strong presence and serves clients in New Jersey. They are a trusted mobile app development company known for their expertise in building innovative and user-friendly applications. WillowTree has worked with leading brands across industries and is renowned for their design-driven approach.
6. Softeq: Softeq is a New Jersey-based mobile app development company that specializes in developing advanced mobile applications for various platforms, including iOS, Android, and Windows. They have a team of experienced developers and offer comprehensive services that encompass the entire app development lifecycle.

These companies have demonstrated their expertise in the mobile app development space and have a strong reputation for delivering high-quality solutions. It's important to note that the best choice for your specific project will depend on your unique requirements and preferences. Consider factors such as expertise, portfolio, client reviews, and budget when making your decision.