We’ve researched and ranked the best California HTML5 mobile app development agencies that build sophisticated and high-quality apps that help brands drive more loyal customers and sales. Compare listings by past work, reviews, cost and size to pick the best fit for you.
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.

Flyaps
VerifiedVerified by the DesignRush team for authenticity and credibility.Award WinnerRecipient of a Best Design Award for outstanding work.AI & Cloud Software Engineering
Flyaps is an AI & cloud engineering company headquartered in New York, with delivery teams in Ukraine and Poland. For 12+ years, we've helped early-stage startups scale into unicorns and modernized legacy businesses into IT leaders...
Top Services:
- Software Development
- AI Development
- IT Services
- DevOps Consulting
- Cloud Consulting
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- Location
- San Diego, California
- Number of Employees
- Under 49
- Average Hourly Rate
- $49/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 accountsFlyaps Services
Data sourced from the agency's DesignRush profileNetSpark IP & Telecom MyersBiz Net Yaana Airbyte Nextgen Clearing JOIN Relocate Shoelace Wireless
Flyaps Reviews & Testimonials

Python Django Review from Andrew Stetsenko
We partnered with Flyaps to build the GlossaryTech Chrome Extension from scratch, including the backend for tech terminology analysis. The goal was to help recruiters, sales professionals, and other non-technical specialists in IT quickly understand the technical terms they encounter every day.The first release shipped back in 2017, long before today's AI tools were available off the shelf. Flyaps built a custom tokenization layer on top of NLTK library to resolve the ambiguity problem - distinguishing "Go" the language from "go to the shop," or "Swift" the framework from the adjective, while also correctly recognizing multi-token terms like "Ruby on Rails" or "Amazon Web Services". It was a pragmatic, precise solution that made the extension genuinely usable from day one.The outcomes have validated that early bet. GlossaryTech now holds "Featured" status in the Chrome Web Store, has passed 25,000 downloads, and consistently serves 10,000+ weekly active users and 2,000+ daily active users. For a niche professional tool, that level of organic, sustained engagement is rare - and it traces directly back to the technical foundation Flyaps put in place.Beyond the engineering, what stood out was how Flyaps engaged with the product itself. They contributed to architecture decisions, flagged edge cases early, and treated scope conversations with honesty rather than upsell. Communication was straightforward throughout, deadlines were met, and the codebase has held up well as we've extended the product over time.I'd recommend Flyaps to anyone looking for a partner who combines solid engineering with genuine product thinking. They've been central to GlossaryTech's success and continue to be a team we trust.

Software Development Review from Dariia Ryzhova
Our collaboration with Flyaps has lasted for several major projects, of which I personally worked with them on two. I am very satisfied with the level of expertise (both technical and domain), the involvement and responsibility of the teams, and the quality of delivery. We successfully brought 2 major products to life together. Flyaps teams have diverse specializations, so I had the opportunity to attract consultants from different fields: software developers, including high-level architects, DevOps, QA, and business analysts.The teams have a modern technology stack and are experienced in Agile development. This allowed for smooth integration with internal teams and processes. It is also important to note that Flyaps provides technical consulting on demand, and this was very valuable service as well. Overall, I can recommend working with Flyaps as a reliable and high-quality partner.
ТОВ ХОТНАЙТС's Review Sourced from Google
Flyaps delivered outstanding results for our e-commerce store! They built a visually stunning and high-performing website that perfectly captures our brand. Since launching, our site speed has improved by over 60%, and we've seen a noticeable increase in our conversion rate. Their team's technical expertise is top-notch, and the new admin panel they created has made managing our operations so much easier. I am happy to recommend this team of professionals.
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsBringing awesome ideas to life
App Development drives innovation at Closeloop Technologies. With our unique expertise, we deliver tailored mobile solutions that enhance user engagement and business growth. Expect collaborative, cutting-edge apps designed to meet your specific goals and elevate your digital presence...
Top Services:
- Software Development
- Web Design
- Mobile App Development
- AI Development
- Wearables
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- Location
- Mountain View, California
- Number of Employees
- 100 - 249
- Average Hourly Rate
- $25/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 accountsCloseloop Technologies Services
Data sourced from the agency's DesignRush profilePacefunding Cordance Premier Talent Partners Omnidian Datacube.ai HomeRun Financing BioStem Technologies UTR Sports AJNA Block & Tam
Closeloop Technologies Reviews & Testimonials

Software Development Review from Rick Tomsic
Global business segment growth is requiring technology to keep up with the increase. Our platform is designed to be scalable and able to be implemented across several nations. We collaborated with Closeloop Technologies to work with our staff in order to scale up the programme.An whole agile team is provided by Closeloop Technologies to participate in our programme. At first, we gave them the data in hopes that they would aid in our execution. They have combined Spring Boot, JavaScript, and AWS cloud technologies.The platform is a value stream and full-suite insurance lifecycle. It is an internal iterative software programme.Working with Closeloop Technologies is simple. They pick up new roles rapidly and possess agile team abilities that are industry standard. The staff not only fits right in, but they also contribute their knowledge and perspectives, making them a vital component of the programme.

Software Development Review from Henrique Dubugras
Services that had been slow or unavailable for weeks had to be brought back up. We must bring back our vital business role. After learning about our issue, the Closeloop project manager assigned a senior database specialist to address it. Our main programmer had a direct conversation with the database specialist of Closeloop after they listened to our problem and asked some follow-up questions. Within less than two hours, the solution to our issue had been verified and implemented.

Software Development Review from Bill Rogers
We occasionally utilize outsourced resources to increase our team's ability to satisfy the commercial demands of our clients. This time, my goal was to create and enhance the products we were providing to clients. Their engineers joined our own team to work on the project, creating MetaTrader-based software for our traders. They assisted us in creating and refining a suite of services that give our clients more functionality; up until that point, the solution had been erratic and unconventional. Their most recent endeavor was the development of an income trading module. We employed a scrum methodology with sprint deliverables and agile planning. Along with narrative points, we also used our in-house bug tracking application for project and task management. Everything was really accurate.
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsTrusted IT Partner for SMBs & Enterprises Since 2001 | Dedicated Teams | Industry-Specific Solutions
Altoros is a 350+ person strong IT consulting and development group. For over 20 years, we've been assisting Global 2000 organizations in getting software products to market faster and reducing the cost of R&D experiments to enable stable business growth...
Top Services:
- Software Development
- Mobile App Development
- Web Design
- Web Development
- Staff Augmentation
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- Location
- Pleasanton, California
- Number of Employees
- 250 - 499
- Average Hourly Rate
- $50/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 accountsAltoros Labs Services
Data sourced from the agency's DesignRush profileSiemens Toyota Hitachi Huawei Denso LikeFolio Dealflo iFit Walmart EQ Bank
Altoros Labs Reviews & Testimonials

Software Development Review from Daria Stolyar
We hired Altoros engineers as an essential extension of our client-facing internal teams. This was a tough decision because our reputation as a brand depends on the overall efficiency of our processes and we needed to make sure all risks are mitigated when it comes to delivery. Altoros has not let us down.Together with Altorosians we successfully deployed a number of tough and technologically complex projects on time. So our collaboration is certainly set to continue.

Software Development Review from Victoria Lewis
We enjoy working with our team, Roman Yurkin, Tatyana Kobzar, Svetlana Kalchanka and Tatiana Anop. They bring expertise and immense value to our business with each piece of work they complete. They are a major part of our business development and delivery.

Ruby on Rails Review from Greg Lipper
In my 30 years in the software business, I have never had as positive an experience with an outsourced development services provider as I have with Altoros. Each Altoros engineer we have worked with has been strong technically, estimated development times accurately, completed projects on time, and delivered code and projects with high quality. Beyond that, they have helped improve our thinking and approach with suggestions and ideas that were better than the spec of instructions we supplied.
Reviews verified by DesignRush and sourced from the agency's profile View All ReviewsEngineering Intelligent & Scalable Solutions.
VentureDive is an award-winning custom software development company dedicated to spearheading digital transformations for Fortune 500 companies across BFSI, CPG/retail, healthcare, transportation, logistics, and QSR industries through its expertise in the realms of Fintech, Data & AI, HealthTech, PropTech...
Top Services:
- AI Development
- Software Testing
- Software Development
- Mobile App Development
- Big Data Analytics
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- Location
- Mountain View, California
- Number of Employees
- 250 - 499
- Average Hourly Rate
- $50/hr
- Minimal Budget
- $25,000 - $50,000
Data sourced from the agency's DesignRush profile, its website, and other relevant accountsVentureDive Services
Data sourced from the agency's DesignRush profileCareem Unilever DNOW Islamic Finder Roland Berger Kaizen Google McKinsey & Company Droobi Kashat
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