Here are reputable U.S. custom software development companies (grouped by type). Short notes show typical strengths — pick based on your project size, industry, budget and required tech expertise.

Enterprise / global leaders

• EPAM — large-scale digital engineering, platform & AI work for enterprises. (investors.epam.com, reuters.com)
• Accenture — full-service consulting + custom software, strong enterprise/cloud/AI capabilities. (gartner.com)
• IBM (IBM Consulting) — enterprise software, cloud, data/AI and systems integration. (gartner.com)
• Cognizant — large IT services firm with custom apps, cloud and AI delivery at scale. (reuters.com)

Product-engineering & transformation specialists

• ThoughtWorks — product-led engineering, agile transformation and software modernization. (businesswire.com)
• Slalom (and Slalom Build) — consulting + product engineering focused on cloud, data and AI; strong U.S. delivery footprint. (slalom.com, prnewswire.com)
• EPAM (also fits here) — strong for engineering-driven product development and platform builds. (investors.epam.com)

Mid-size / design-focused and boutique shops

• Atomic Object — US-based consultancy good for custom apps, embedded and IoT, hands-on teams. (atomicobject.com)
• WillowTree — mobile and digital product specialists (design-led, enterprise & consumer apps). (willowtreeapps.com)
• DockYard — design-first web & product engineering for startups and enterprises. (linkedin.com)
• Fueled — app-centric, product design + mobile/web development for consumer-facing products. (linkedin.com)

Nearshore / value / staff-augmentation options

• FullStack Labs — product engineering teams, good for startups and growth-stage companies; transparent pricing/models. (fullstack.com)
• Saritasa — US-based teams with full-cycle development (mobile, web, AR/VR, IoT). (clutch.co)
• INOXOFT / other Clutch-ranked firms — numerous U.S. firms listed and reviewed on Clutch (search filters by hourly rate, industry and reviews). (clutch.co)

Quick selection checklist (use to compare firms)

• Project scope & complexity (MVP vs enterprise platform)
• Industry experience (healthcare, finance, retail, etc.)
• Team model (onshore, nearshore, mixed, staff augmentation)
• Tech stack & architecture (cloud provider, frontend/backend languages, AI/ML needs)
• Budget & timeline (hourly vs fixed, expected delivery date)
• References & case studies (look for similar projects and client reviews)

If you want, I can narrow this to a 3–5 company short‑list based on your budget range, industry, tech stack and whether you prefer enterprise consultancies or boutique product teams — tell me those details and I’ll tailor recommendations.