API development services help you build and connect the interfaces that let your applications, partners, and third-party tools exchange data. Mobilions designs, builds, and integrates custom REST and GraphQL APIs, then secures and documents them so your systems and outside developers can rely on them.
Whether you need a new public API, private services between your apps, or third-party API integration, you get clean architecture, clear documentation, and code you own. Our senior engineers build API-first, so your product stays ready for web, mobile, and partner use.
Part of our backend development services →
API development is the work of designing, building, and maintaining an application programming interface (API): a defined set of rules that lets one software system request data or actions from another. A well-built API gives other apps a predictable way to connect without touching your internal code. REST and GraphQL are the two common approaches. A REST API exposes data through fixed endpoints and standard HTTP methods, which keeps it simple and widely supported. A GraphQL API lets clients request exactly the fields they need in one call, which reduces over-fetching for complex apps.
The right choice depends on your use case. We help you pick based on your data, your clients, and how your API will grow over time.
The right choice depends on your use case. We help you pick based on your data, your clients, and how your API will grow over time.
Our API development services cover the full build, from first design to live monitoring:
Custom REST API development for clean, predictable endpoints.
GraphQL API development for flexible, field-level queries.
Third-party API integration for payments, CRM, messaging, and more.
API-first architecture so your backend serves web, mobile, and partners.
Authentication and security with OAuth, tokens, and role-based access.
API documentation your team and external developers can follow.
Versioning so you can change APIs without breaking existing clients.
API gateways and rate limiting to manage traffic and protect resources.
Testing and monitoring to catch errors before your users do.
Five steps from endpoint design to an API your product and partners rely on.
We map your data, users, and use cases, then design the endpoints, schemas, and contract your clients will depend on.
Our engineers build your REST or GraphQL API with clean, tested code, connected to your data through reliable database integration.
We add authentication, access control, and rate limiting, then write documentation your team and partners can use.
We test each endpoint, connect third-party services, and confirm your API behaves correctly under real load.
We ship your API to your cloud services, set up monitoring and logging, and support versioning as your product grows.
Where API development pays off, from public APIs to internal integrations.
API development services fit teams that need their systems to talk to each other or to the outside world. You may be a startup exposing a public API so partners can build on your product, or a company connecting internal apps that no longer share data cleanly.
You might also need our API integration services to bring payments, shipping, CRM, or analytics into your product. If your current APIs are slow, undocumented, or hard to change, we can rebuild them on a cleaner foundation.
This is for founders, product teams, and engineering leaders who want APIs that are secure, documented, and built to last.
The essentials of our API development services, at a glance.
Custom REST and GraphQL APIs built for your data and workflows.
Third-party API integration to connect payment, CRM, and other services.
Authentication, security, versioning, and rate limiting built in from the start.
Clear API documentation your team and outside developers can actually use.
Code and docs you own, built by senior US-first engineers.
Mobilions proves its work through real, shipped products, not invented metrics. These are approved case studies with no fabricated results, revenue, or timelines.
An AI translation app that handles Hebrew gender, slang, and context most translators miss.
A multi-vendor beauty marketplace with vendor storefronts, real-time inventory, and a vendor operations app.
A bill-splitting app that settles up through the payment apps people already use.
An app that turns TikTok and Instagram food videos into saved, mapped, bookable spots.
Why engineering leaders trust us with the interfaces their products depend on.
Since 2016, Mobilions has delivered 250+ Projects for 100+ Clients across 20+ Countries.
Our senior, US-first engineers approach custom API development as part of full products, so your API fits your backend development and custom software development rather than standing apart from it.
You own the code and the documentation, with no lock-in and no black boxes.
As an API development company, we build for the long term, so your API stays secure, versioned, and ready as your traffic and integrations grow.
In their own words, Mobilions' clients describe fast delivery, clear communication, and senior, trustworthy engineering.
Great experience working with this team. They completed the development work quickly and efficiently without wasting time. Communication was clear and consistent, they understood the requirements well, gave smart suggestions, and delivered exactly as discussed. I'd highly recommend them to anyone looking for a reliable, fast, and skilled app development team.
We worked with Ankit, Mayur, and Tushar to build the first version of Baba Hebrew for iOS and Android, and they delivered super fast. The team was responsive, reliable, and efficient, taking the idea from zero to a working app in record time. I'd recommend them to anyone who wants to get an MVP live quickly.
Tushar and Ankit did an outstanding job developing our native iOS (Swift) and Android (Kotlin) apps. They were efficient, responsive, and technically strong throughout. Thanks to their work, we launched successfully and gained over 1,000 users in the first 30 days. Highly recommend this team for quality mobile app development.
It was a wonderful experience working with Tushar, Ankit, and their team. They built a great mobile app for me and truly brought my vision to life. What stood out was not just their technical skill but their attitude: always positive, solution-oriented, and incredibly patient. They went above and beyond at every step, finding creative workarounds and staying committed even when things got challenging. Extremely professional and trustworthy. I would absolutely hire them again.
Ready to build a new API or connect the systems you already have? Tell us what your product needs and our engineers will map the fastest path to a secure, documented API. Contact Mobilions to start your API project.
Direct answers to the questions teams ask before an API build.
API development services are the design, build, integration, and maintenance of APIs that let software systems share data and actions. At Mobilions, that covers custom REST and GraphQL APIs, third-party API integration, security, documentation, and versioning, delivered by senior engineers with code you fully own.
Cost depends on the number of endpoints, the complexity of your data, and how many third-party services you connect. A small internal API costs far less than a public API with heavy security and documentation needs. Tell us your goals and we will scope a fixed estimate for your project.
A REST API exposes data through fixed endpoints and standard HTTP methods, which is simple and widely supported. A GraphQL API lets clients request exactly the fields they need in one call, which reduces over-fetching for complex apps. We help you choose based on your clients and data.
Yes. Third-party API integration is a core part of our work. We connect payment, shipping, CRM, messaging, analytics, and other external services to your product, handle authentication and error cases, and make sure data flows correctly so your users get a reliable experience.
We secure APIs with authentication such as OAuth and tokens, role-based access control, input validation, encryption in transit, and rate limiting through API gateways. We also test for common vulnerabilities and set up monitoring so your team can spot unusual activity early.
Yes. You own all API code and documentation we produce, with no lock-in. We hand over clean, tested code and clear docs so your team, or any developer you choose, can maintain and extend the API without depending on us.
Yes. Every API we build comes with documentation your team and external developers can follow, plus a versioning plan. Versioning lets you improve or change your API over time without breaking the apps and partners that already depend on it.
Let's build your next big thing. Share your idea and get a free consultation. We respond within one business day.
