Our analysts identified the top outsourcing software development companies in California providing cutting-edge services that answer key business problems, from building technical software, designing websites or mobile apps to integrating operating systems and more. Narrow down your search by team size, budget, reviews and more to select the best developer for your company’s needs.
Organic rankings are determined by five factors: top services, reviews, portfolio, awards/press, and team expertise. Sponsored listings pay for a placement that appears above organic positions. Sponsorship does not affect star ratings or review content - read more on our methodology page.
Your trusted AI software development partner
When startups and enterprise clients need AI-driven software or staffing, Diffco delivers custom mobile, web, and IoT applications backed by 17 years of delivery experience. San Jose-headquartered, the team has built solutions for American Express, Starbucks, Whole Foods, and Mars, using React, Node.js...
Top Services:
- AI Development
- Software Development
- Staff Augmentation
- Mobile App Development
- Web Development
- Show more
- Location
- San Jose, California
- Number of Employees
- 50 - 99
- Average Hourly Rate
- $110/hr
- Minimal Budget
- $25,000 - $50,000
- Portfolios Count
- 31 Projects Listed
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsDiffco Services
Data sourced from the agency's DesignRush profileMars Food Rocket FlashGrid Nokia Instreamatic Quire Legionfarm Latoken Genius One Shift
Diffco Reviews & Testimonials

Mobile App Development Review from Elvera Kaparchuk
SaveIT is receipt management on autopilot. You connect your email once, and we import your receipts, extract every line item with AI, categorize it, and sync it with QuickBooks. The AI isn't a feature of the product, it is the product. If it reads a receipt wrong, everything downstream is wrong. We brought Diffco in to work on that core. Since April they've worked on our AI models, fixed security problems in the platform, and helped us build a real strategy around where AI belongs and where a conventional solution is the better call. The most important change was measurement: extraction accuracy is now a number we evaluate every change against, instead of something we judge by trying a handful of receipts. They were also honest in a way I didn't expect from an AI firm. When we assumed a problem needed a stronger model, they showed us it was in our data. That saved us time and money. They continue to support the AI side of the product, and they're easy to work with; direct, technically deep, and clear about trade-offs.

AI Development Review from Ivan Pasichnyk
We brought Diffco in to deliver the AI and computer vision components for one of our clients, an image generation startup. Because the work sat inside our own client relationship, we needed a partner we could trust to operate at our standard without us managing them day to day - and that is exactly what we got. Diffco owned the technical approach, built the computer vision and AI layer, and delivered the full scope in three months, on schedule. The engineering quality was high, they raised the right questions early instead of late, and they handled the confidentiality the project required without us having to chase it. After delivery they stayed on to support the system, which mattered to us as much as the build itself. When you subcontract a technical project inside your own client relationship, the risk is that the partner makes you look bad. Diffco did the opposite. They've earned our trust and we'd work with them again.

AI Development Review from Oleg Sotnikov
Diffco built a complex, production-grade AI agentic system and backend for our client's fintech platform owning architecture, AI/ML components, and AI agents in a security- and compliance-sensitive environment. They delivered on time and within budget, communicated proactively, and operated like part of our own team, taking ownership and suggesting better solutions throughout. Deep AI/ML and senior backend expertise. We'd happily work with them again.
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsWhere Exceptional Apps Are Just The Beginning
When enterprises need custom apps across healthcare, fintech, and ecommerce, BitsWits delivers mobile and web platforms using React Native, Flutter, Swift, and blockchain stacks. The Houston-based studio handles iOS, Android, and cross-platform builds with in-house AI, IoT, and AR/VR capabilities. Clients...
Top Services:
- Mobile App Development
- Software Development
- VR/AR
- Blockchain
- AI Development
- Show more
- Location
- Los Angeles, California
- Number of Employees
- 100 - 249
- Average Hourly Rate
- $25/hr
- Minimal Budget
- $25,000 - $50,000
- Portfolios Count
- 12 Projects Listed
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsBitsWits Services
Data sourced from the agency's DesignRush profileFitNow Wisu Soul Scribe Grease Monkey Beats
BitsWits Reviews & Testimonials

Mobile App Development Review from Sydney Malone
With the development of our Mobile App, BitsWits performed a fantastic job. Their team was quick to respond and produced a great application that runs smoothly on all platforms. We are quite happy with the result.

Mobile App Development Review from Benson Sung
They created a Mobile app for Medical services, and patient management has changed greatly as a result. The app works well with our current systems, is safe, and is simple to use. Their team produced a top-notch product on schedule while paying close attention to our unique requirements. We are really pleased with their work and heartily recommend BitsWits to anyone in need of app development services.

Mobile App Development Review from Steve Garry
The outcomes of our collaboration with BitsWits to develop an Online Food delivery app were outstanding. Real-time tracking is integrated into the app, which makes it easy to use and has significantly enhanced our customer support. Their development staff was quick to respond and took care of all of our requests. We couldn't be more pleased with the result!
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsYour Product Engineering & Gen AI Partner
Simform is a premier AI-native digital engineering company specializing in Product Engineering, Agentic AI, Data, Cloud and Enterprise Transformation. We help enterprises and high-growth ISVs build sophisticated AI-integrated digital solutions and scalable platforms...
Top Services:
- Software Development
- Cloud Consulting
- AI Development
- Big Data Analytics
- DevOps Consulting
- Show more
- Location
- Los Angeles, California
- Number of Employees
- 1000 & Up
- Average Hourly Rate
- $30/hr
- Minimal Budget
- $25,000 - $50,000
- Portfolios Count
- 8 Projects Listed
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsSimform Services
Data sourced from the agency's DesignRush profileSony Music (EMI) Pepsico Zep Inc Intralinks Nxt-ID FreeWire Inc Accent Inc Mission Rabies DoggyBnB Drizzle Labs
Simform Reviews & Testimonials

Software Development Review from Andrew Muroff
We worked with Simform for many years ongoing software development on our core product, the Strainprint mobile outcomes tracker for medical cannabis patients. We have only positive things to say about their work product and attention to detail. We highly recommend them and will work with them again.

Software Development Review from Robel Yemane
I've been working with Simform for over six months now. The engagement began with bringing our subscription management platform in-house, and we've since expanded the partnership to other projects due to their broad skill set and consistent reliability. They've gone the extra mileeven over weekends and public holidaysto help us move faster when needed. Communication and project management have been excellent, with any issues swiftly addressed. It genuinely felt like Simform was invested in our success. Having worked with similar firms throughout my career, I can confidently say Simform stands out and comes highly recommended.

Software Development Review from Russ Makhauri
We worked with Simform to hire a front-end engineer for our SaaS platform. The process was well-organized, and their team was professional, responsive, and efficient. They quickly identified a candidate who met our technical requirements and ensured a smooth onboarding process.Simforms communication and project management were strong throughout the engagement. They were proactive in addressing feedback and remained flexible in adapting to our needs. While there is some room for improvement in developer vetting and quality assurance, their overall service was excellent.For companies looking to scale their development teams efficiently, Simform is a reliable partner. Their structured approach, responsiveness, and commitment to client satisfaction make them a great choice. We would recommend them without hesitation.
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsFUELING DISRUPTION
EffectiveSoft is an AI-enabled product engineering company focused on digital products and enterprise systems. We combine software engineering, UX expertise, and AI capabilities to help companies build products that can adapt to changing requirements, integrations, and growth...
Top Services:
- Software Development
- Mobile App Development
- Big Data Analytics
- AI Development
- ERP Consulting
- Show more
- Location
- San Diego, California
- Number of Employees
- 250 - 499
- Average Hourly Rate
- $50/hr
- Minimal Budget
- $25,000 - $50,000
- Portfolios Count
- 29 Projects Listed
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsEffectiveSoft Services
Data sourced from the agency's DesignRush profileCITY INDEX TruBridge CNote Plato Intelon Optics InCheq Nissin Foods Soutron Ltd. BullionRock InContinuum
EffectiveSoft Reviews & Testimonials

Software Development Review from Alex Silverstein
Over the past 13 years, I’ve valued the opportunity to work alongside this team. Their expertise played a central role in my company’s success, and I’ve come to rely on them for their consistency, attention to detail, and thoughtful approach.

Software Development Review from Philipe Araujo
We have had a highly positive experience utilizing EffectiveSoft's staff augmentation services for our Business Analyst and Quality Engineer needs. The professionals provided were not only highly skilled and knowledgeable but also integrated seamlessly with our existing team, requiring minimal ramp-up time. Their expertise in their respective fields significantly enhanced our project's efficiency and overall quality. We confidently recommend EffectiveSoft for any organization seeking top-tier talent to augment their teams and drive successful project outcomes.
Software Development Review from Sasja Ihn Christensen
Maersk Broker is pleased to provide this reference letter for EffectiveSoft, our trusted collaborator for complex web projects. From the initial stages of our projects, the team at EffectiveSoft demonstrated a deep understanding of our requirements and have been apro-active part of any problem-solving process. The team of offshore developers has been well-run through their lead developer, and we have only experienced a professional approach to our projects, as well as a pleasant and trust-based collaboration = between all members in the EffectiveSoft team and our own team. EffectiveSoft has furthermore proved to be highly flexible, adapting to our evolving needs and delivering reliable results under shifting circumstances and shifting priorities. They have furthermore been very quick to find and add the necessary resources to the team when needed, and we have only experienced professional and highly skilled consultants. This has also made on-boarding into projects faster and more efficient.In conclusion, it has been a pleasure working with EffectiveSoft, and I have no doubt that they will continue to be an asset to any collaborators in the future, adding value through their professionalism, dedication and understanding of business needs.
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsCertified E-Commerce Development Company
Certified E-Commerce Development Company...
Top Services:
- eCommerce Development
- Web Development
- IT Services
- Web Design
- Mobile App Development
- Show more
- Location
- San Francisco, California
- Number of Employees
- 50 - 99
- Average Hourly Rate
- $40/hr
- Minimal Budget
- $25,000 - $50,000
- Portfolios Count
- 16 Projects Listed
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsDinarys Services
Data sourced from the agency's DesignRush profileAroma Kava LastBid Budu Sushi Magento 2 Migration Rite Space Bookbreakrs Can Vivat Udifo ServisBook
Dinarys Reviews & Testimonials

eCommerce Development Review from André Schörnig
We have been working with Dinarys on our Shopify store for quite some time, and the experience has been great. From the very beginning, communication was clear, efficient, and reliable. The Dinarys team consistently delivered detailed proposals, stuck to agreed timelines, and offered well-structured solutions tailored to our needs. Their technical expertise is impressive, but what really sets them apart is their proactive attitude and genuine commitment to our project. Whenever we had questions or changes, they responded quickly and constructively. Its a true pleasure to work with a partner who feels like an extension of our own team. Highly recommended!

Web Development Review from Nissrine Kohen
Weve been working with Dinarys for quite some time now, mainly collaborating on Magento and Shopware development projects. Their developers consistently show solid technical expertise and a good understanding of our expectations and workflow.Communication is generally smooth, and response times are quick. Whenever issues arise, the team is open to feedback and acts quickly to improve. Over time, weve seen a positive evolution in their proactiveness and alignment with our teams way of working.They are flexible and collaborative, and its clear that they genuinely aim to build long-term partnerships. For the quality delivered, we feel the pricing is fair and transparent.All in all, weve been satisfied with our cooperation and would recommend Dinarys as a development partner, especially for companies looking for experienced backend developers in Magento and Shopware.
Nina Liashuk's Review Sourced from Google
Smooth, reliable cooperation every step of the way. They're quick to respond, easy to work with, and consistently deliver strong results. Their reliability and the quality of support have stood out the most. A team we would recommend without hesitation.
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsModern Times, Modern Measures. We Call It the Wizeline Way.
Wizeline is a recognized global leader for on-point, outsourced design and technology services. Headquartered in San Francisco, the firm provides optimal data leverage, new market capitalization, product development, and much more. More than 10 million people use Wizeline products every day...
Top Services:
- Software Development
- Mobile App Development
- AI Development
- Web Design
- UI/UX Design
- Show more
- Location
- San Francisco, California
- Number of Employees
- 500 - 999
- Average Hourly Rate
- $100/hr
- Minimal Budget
- $25,000 - $50,000
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsWizeline Services
Data sourced from the agency's DesignRush profileFox Networks Group USA Rugby WSJ Banco Base Mastercard Coppel Shape Security TWG Dover Digital Arts Network Barron's
Wizeline Reviews & Testimonials
David Brown's Review Sourced from Google
HORRIBLE, company -- must avoid - management has zero ethics, constantly lies through teeth, noncommittal , doesn't give a straight answer to anything. Avoid!
Michael Noga's Review Sourced from Google
I thought this was crunchbase inc? Wizeline? But same type of business. Well as long as I know it is real but if so then the name I have is my own creation. It is called crunchbase inc
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsYour AI-Driven Software Development Partner
Savvycom is an AI-driven software development and IT consulting company founded in 2009, helping enterprises design, build, and modernize digital systems that deliver measurable business outcomes. Recognized as one of Vietnams Top 10 Digital Technology Companies, Savvycom partners with organizations...
Top Services:
- Mobile App Development
- Software Development
- Web Development
- IT Services
- AI Development
- Show more
- Location
- Laguna Beach, California
- Number of Employees
- 500 - 999
- Average Hourly Rate
- $40/hr
- Minimal Budget
- $25,000 - $50,000
- Portfolios Count
- 9 Projects Listed
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsSavvycom Services
Data sourced from the agency's DesignRush profileKB Bank Citeco. Capsikin Path. North America & Europe: TaylorMade
Savvycom Reviews & Testimonials
Amelia's Review Sourced from Google
Working with Savvycom was a positive experience. The team was professional, responsive, and delivered quality work on time. Communication was smooth, and they were always willing to help when needed. Highly satisfied with the collaboration.
Nguyên Ngọc's Review Sourced from Google
From my perspective as a former employee: I worked here for almost a year. Colleagues and staffs here are pretty open-minded but employees are highly underpaid. Also in order to get a job here you must have decent technical skills and English language ability.Pros: nice office, friendly staffs that really take care of employeesCons: underpaid salary
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsTranslating Ideas & Research to Market
KritiKal Solutions is a technology design house and holds 22+ years of experience in AI, Computer Vision, Software Applications, Cloud and Mobile-based Solutions, Embedded Systems, Generative AI and Large Language Models. We specialize in R&D, product engineering, and innovation services...
Top Services:
- AI Development
- IoT
- Mobile App Development
- Software Development
- Wearables
- Show more
- Location
- Los Angeles, California
- Number of Employees
- 100 - 249
- Average Hourly Rate
- $25/hr
- Minimal Budget
- $25,000 - $50,000
- Portfolios Count
- 4 Projects Listed
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsKritikal Solution Services
Data sourced from the agency's DesignRush profileVector USA BYJU'S P&G Columbus Continental Honeywell ITC Stryker G&D University of Berkeley
Kritikal Solution Reviews & Testimonials
Aakriti Bhatnagar's Review Sourced from Google
Great place to work.Very good learning opportunity.Best place for freshers to learn and gain knowledge.Supportive and understanding colleagues.
Jobin John's Review Sourced from Google
One of the best aspects of working at KritiKal Solutions is the opportunity to collaborate with talented professionals across multiple domains. The company promotes a culture of innovation, knowledge sharing, and continuous improvement.
twinkle kumari's Review Sourced from Google
A great workplace that encourages continuous learning, teamwork, and professional growth. The management maintains an open-door policy, making it easy to share ideas and collaborate across all levels of the organization.
Reviews verified by DesignRush and sourced from the agency's profile View All Reviews
Related Services in California
Related Software Development Specializations in California
Popular Services
The Benefits Of Top Outsourcing Companies In California
Why companies trust DesignRush
Every agency is independently vetted before it can be listed or ranked
Some agencies pay for sponsored placement, clearly labeled and held to the same vetting standards.
Latest Trends Related to Outsourcing Software Development










