Custom Fitness App
Development & Project Rescue Services
Build from scratch or rescue your fitness app? We do both.
Onix is your go-to sports and fitness app development company when things go off track. We don’t just fix – we optimize. From bug-ridden prototypes to never-scaled fitness software, we rescue, rework, and relaunch your product quickly and reliably.
Onix’s senior fitness app developers jump into messy codebases, outdated designs, or half-built fitness apps and turn them into revenue-ready, scalable, cutting-edge mobile fitness app solutions powered by AI, innovative UI/UX, and solid engineering. No more lost users. No more missed revenue. Just a fitness app that performs.
Trusted by clients worldwide
0+
successfully delivered
projects
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years of software
development
experience
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countries represented
by our clients
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talented developers and
experts on staff
Stop losing users – deliver what they expect
Your users expect more than just a step counter. You need a reliable, interactive platform that motivates, guides, and retains users daily.
0%
of users delete fitness apps due to bugs, poor UX, or slow performance
0%
of users expect integration with wearables and real-time tracking
0 in 4
users say personalization (AI coaching, adaptive plans) keeps them coming back
0%
of fitness app users drop off within 10 days if the app lacks engagement or value
Meet the expectations of modern users with our custom fitness solutions
Whether you're launching a new fitness app or fixing a failed one, we know what modern users expect, and we build exactly that. Onix delivers fully custom, user-focused fitness app development solutions packed with features users love:
Coaching platforms
Smart equipment apps
Workout and training apps
Yoga and meditation apps
Real-time activity tracking apps
Rehabilitation and physical therapy apps
AI personal training assistants
AI-powered workout and nutrition plans
We build, rescue, and scale: our fitness application development services
Onix is your end-to-end fitness mobile app development company with a strong focus on long-term success: from rebuilding unstable code and refining UX to integrating AI-driven features, app optimization, and scaling your infrastructure.
Our fitness app development services adapt to your needs: new product development, app rescue, modernization, maintenance, or full-scale growth. We’ll get you where you need to be.
Build fitness web & mobile apps that engage users and drive growth
Rescue & rebuild your fitness app. Don’t start over, start smarter
Wearables & IoT integration that drives engagement and retention
Connect everything with smart API & system integrations
Validate first: MVPs for fitness startups
Scale with confidence: we build infrastructure that grows with you
Whether you're building from scratch or fixing what's failing, Onix is your one partner for every stage of your custom fitness app development.
We don’t just promise.
We build results.
USA
Sports & Fitness
From concept to a community-loved app
Solution:
We synced wearables with sleek UX to deliver real-time swim analytics.
Result:
A smart swimming fitness tracker with a growing swimmer base.
USA
Sports & Fitness
From scaling issues to seamless coaching
Solution:
Onix fixed architecture, UX, and payments to launch a sleek, scalable SaaS for fitness pros.
Result:
A thriving platform used by countless coaches and clients.
USA
Sport
From a broken vendor handoff to a scalable platform
Solution:
Onix rebuilt the app for iOS and Android with smooth video coaching, better UX, and a solid architecture.
Result:
A stable app training golfers worldwide.
USA
Sports & Fitness
From decent to best-in-class
Solution:
We redesigned the UX, added key features, and scaled the app over 3 years.
Result:
A fan-favorite fitness app with 200 K+ downloads, 30 K+ active users, and a 4.8 rating, boosting revenue and retention.
Our fitness software services drive results you can measure
0% faster
time to market
with lean, Agile development
0% lower
development costs
thanks to reliable architecture and reusable components
0% faster ramp‑up
and 30% less rework
thanks to our built-in fitness domain expertise that keeps your project on target from day one
0% less
time spent
on bug fixes with proactive QA and clean, maintainable code
0x more
user engagement
through gamification, wearable integration, and personalization
0x more
user growth
supported by scalable cloud infrastructure and microservices
Testimonials
Go beyond basic. Let's wow your users.
Modern fitness apps aren’t just about tracking steps and receiving notifications.
Users expect engaging, intelligent experiences, and that’s where Onix comes in.
From AI to VR, we integrate advanced technology that transforms your fitness app into something smarter, hyper-personalized, and more addictive.
AI-powered personalization
Our AI experts deliver hyper-personalized workout plans, nutrition advice, and habit-building tips tailored to users' goals, preferences, and performance data.
Computer vision for form tracking
We use smartphone or webcam footage to analyze users' posture and exercise form in real-time, helping them train smarter and avoid injury.
VR fitness experiences
Our engineers create immersive workout environments that turn fitness into fun. These environments are perfect for guided sessions, gamified training, or virtual group workouts.
Wearable & IoT integration
We connect seamlessly with smartwatches, heart-rate monitors, and gym equipment to collect real-time health data and enhance in-app progress tracking.
Voice recognition & virtual coaching
Our remote specialists add hands-free navigation and real-time voice feedback from AI-powered virtual trainers that guide users through routines and motivate them.
Predictive analytics
We help you anticipate churn, optimize workout recommendations, and improve retention with data-driven insights and behavior modeling.
No matter where you start, our development process gets your fitness app to the finish line
As a fitness app development company, we build practical solutions that deliver real results, from building sleek new solutions to rescuing projects that have lost momentum.
We combine proven workflows with modern tools, such as AI code analyzers and automated testing, to speed things up and maintain high quality.
Collaborating with Onix means zero guesswork, no hidden surprises, just transparent, results-oriented development
Custom fitness software development process
We build custom fitness software that performs seamlessly from the start.
Here's how we deliver real value to your business and your users:
01
Discovery & planning
We begin by understanding your business, goals, and users. Through a short discovery phase, we define your MVP, product roadmap, and technical plan.
02
Design & prototyping
Our UX/UI designers create intuitive interfaces that work for real users. We validate ideas early with clickable prototypes.
03
Agile development
Our professional developers build your product in short sprints, delivering working features regularly. You’ll get updates weekly and see real progress.
04
Testing & launch
We thoroughly test functionality, speed, and security so that you can launch confidently.
05
Post-launch support & scaling
Need new features, improvements, or AI integrations down the road? We’re here for the long haul.
Build a custom fitness solution that performs, scales, matches your vision, and keeps users returning.
Fitness software rescue process
We step in when fitness software isn’t working as it should, fixing destructive code, delays, and performance issues.
Here is our process for rescuing fitness apps that need a second chance:
01
Quick audit & recovery plan
We quickly audit your codebase, tech stack, and delivery gaps. In just 1-2 weeks, you’ll get a clear rescue audit report.
02
Re-engineering & improvements
Armed with audit insights, our dedicated team stabilizes critical features, reworks malicious code, integrates ML, and cleans up the legacy mess.
03
Transparency at every step
You’ll see weekly sprint progress and demos, and track everything on your dashboard. No guesswork.
04
Final QA & stabilization
We ensure everything runs smoothly with stress testing, performance tuning, and security audits.
05
Ongoing support
Post-rescue, we offer continued support and enhancements to future-proof your product.
Fix what’s broken and rebuild your fitness app into a fast, scalable, user-ready product.
The right tools for your fitness app – nothing more, nothing less
Backend development
Python,
Node.js,
Java,
PHP,
Ruby,
.NET
Frontend development
React.js,
Vue.js,
Angular,
JavaScript,
HTML5,
CSS3
Mobile development
Kotlin,
Java,
Swift,
Objective-C,
React Native,
Flutter
AI
MATLAB,
TensorFlow,
PyTorch,
SciKit-Learn,
Pillow
Platform customization
Shopify,
WordPress,
Salesforce,
Magento,
OpenCart,
Canva
VR/AR and 3D design
Unity,
Visual Studio,
Blender,
Maya,
Houdini,
V-Ray
Cloud storage
AWS,
Azure,
GCP (Google Cloud Platform),
Heroku,
DigitalOcean,
Docker
Our experience across industries
How to start growing your fitness business with Onix
Whether you’re starting from scratch or rescuing a stalled product, Onix is here to help you build high-quality, scalable solutions or fix what others couldn't.
1
Schedule a consultation
It starts with a conversation – schedule your free consultation.
2
Sign
an NDA
We’ll sign an NDA. Then our experts will review your code, software, or concept at no cost.
3
Get audit report
Within a week or two, we’ll send you an audit report or development plan outlining what’s wrong, why it’s happening, and how we can move forward.
Big idea? Tough situation? Either way, your fitness project could be the next big thing.
Insights from our experts
FAQs
What types of fitness apps can you build?
Our firm builds all kinds of tailored fitness app development solutions: from personal training and workout and motivation apps to nutrition trackers, wellness platforms, sports and running apps, wearables-integrated apps, and large-scale fitness marketplaces.
Can you rescue my existing app or take over development from another team?
Absolutely. We specialize in fixing underperforming fitness apps. Whether your code is messy, deadlines were missed, or your current team dropped the ball, we step in, clean up, and get things moving again.
What happens after I submit a request for your fitness software development services?
We begin with a free consulting session and an NDA. Then, our experts conduct a no-cost audit of your project’s code or concept. Within 1–2 weeks, you’ll receive a detailed audit report or fitness custom app development plan outlining what’s wrong, why it’s happening, and how we can move forward.
What if I just have an idea but no design or technical specs yet?
No problem. When you hire us, we’ll help shape your idea, define the scope, build the MVP, and support its growth. You’ll have expert guidance every step of the way.
Do you work with startups or only large companies?
Both! We love working with ambitious startups just as much as established fitness brands. Whether you need an MVP or a scalable platform, we’re in your corner.
What does working with Onix look like?
Expect clear communication, weekly check-ins, and full transparency. With our outstaffing model, you get dedicated professionals who act as an extension of your in-house team.