API Development Guide: What to Keep in Mind When Building API-Focused Products

16 min read


Companies across different verticals use APIs to enable communication between the client and server side of their apps, to integrate with third-party software, and to allow external apps to access their system. Moreover, building and monetizing custom APIs can become an essential part of a business development strategy. 

If APIs play a crucial role in your project, the requirements for their development may be rigorous. You need to know how to meet technical challenges, what protocol to choose, and what practices to apply for building top-notch API-focused products. The following guide aims at answering these questions.      

API Protocols: Types & Development Specifics

Let’s first explore different kinds of APIs and their development features so that you can identify the most suitable protocol for your project. Currently, the top approaches in custom API development are REST, GraphQL, and gRPC.


REST, also known as Representational State Transfer, refers to APIs that are stateless, meaning each request holds all the details necessary to complete it. A vast majority of backend developers are familiar with REST API development. This is the most frequently used and versatile type of API, utilized in a large number of software projects. Being a simple protocol with a low barrier to entry, REST APIs are unlikely to face future support issues. 

With REST, we clearly understand what and how we’re requesting, and we know what response to expect. The same applies to errors; we can pinpoint the error based on status codes at any given moment. We can also upgrade this protocol with custom elements to make errors more comprehensible on the client side.

Advantages of REST: simplicity, speed, and a clear relationship between the client and server, ease of caching responses, and built-in security features.

Downsides: a lack of flexibility due to the server’s standardized responses. For instance, let’s say we have a list of company managers, and on one page, we might want to have names with roles and contact details, and on another, just the names without any other data. In the REST scenario, we either have to use one request everywhere, responding with unnecessary data and using up bandwidth, or write a separate request for each page, leading to code duplication and complexity. Usually, the same request is used throughout.


GraphQL is a query language for APIs developed by Facebook. More flexible than REST APIs, GraphQL lets developers obtain all needed data in a single request (client-driven query). Developers can also specify the data type they wish to receive from the API.

GraphQL resolves the issue of request-response interaction. We leverage a specific query language that instructs the server about the client’s specific data needs at any given moment. Revisiting the managers’ example, the client isn’t defaulted to receive standardized data but can choose the needed info (like name and phone number), and the server responds with this specific information. 

This system is perfect for apps requiring greater flexibility and scalability, complex systems, and microservices.

Advantages of GraphQL: this approach saves bandwidth and boosts performance, providing more flexibility and scalability.

Downsides: the query language is more complex, and the entry barrier is fairly high, potentially complicating support if you lack specialists. The community is also smaller. 

GraphQL is flexible for end users, but it involves a certain load on the server. The development of GraphQL is much more complicated than the development of REST APIs because there are more cases of how a request can be made and certain complex requests from the client may appear, which will affect the server’s work. Therefore, ensuring good performance requires a certain amount of experience and expertise from your developers.

Anton Lohvynenko

Solution Architect


gRPC, an open-source RPC framework created by Google, is considered to be a high-performance API development technology. gRPC leverages Protocol Buffers, a language-agnostic, platform-neutral mechanism for serializing structured data. 

Unlike REST and GraphQL, which are quite similar, gRPC offers a different client-server interaction and is only usable with the HTTP/2.0 protocol. This advanced protocol provides benefits in data compression, user connection, and more. 

gRPC is perfect for projects with high-performance communication requirements.

Advantages: gRPC communicates with the server through streams and its query language, making the whole process appear as if it’s happening within a single system, regardless of whether you’re on the front end or back end. The front end can call methods written on the backend. However, in reality, you need to write server methods and build them first, and only then the front end understands that these methods exist and can be used. Setting up all this requires experience with this type of API.

Other advantages include more compact data, better performance, and quick responses.

gRPC is built on top of RPC (Remote procedure call) and is a key that provides more flexibility for executing long-running requests. With Rest and GraphQL a complex request can fail due to a timeout, and with gRPC you can build such an architecture where long-running requests will be executed easily.

Anton Lohvynenko

Solution Architect

Disadvantages include a small community (the protocol is still evolving) and a relatively high entry barrier. Understanding the data transmission protocol is also important; each newcomer is likely unfamiliar with this protocol and will need to be trained. Compared to other approaches to API development, this one is quite complex and takes more time, which is not always justified for the project.


The table below illustrates the main difference between the mentioned approaches to API development. But it’s also important to recognize the experience of your developers, among other things. 

Each approach has its specifics that require certain knowledge and skills. Also, you’ll need API support in the future. This is the reason why REST, despite its imperfections, remains the most popular API development method.

Criteria REST GraphQL gRPC
Data transfer format JSON or XML GraphQL Protocol Buffers
Transport Protocol HTTP/1.1 HTTP HTTP/2
Performance Medium  Faster  The fastest
Query flexibility Low High Medium
Support for caching Strong Weak Weak
Community Large Growing Growing

REST vs GraphQL vs gRPC Comparison

Key Features for API Solutions

During the initiation and progress of the API development, software engineers should consider a few crucial points. This will ensure the security and efficiency of your APIs.

Authentication and Authorization

Authentication verifies the correct identity, while authorization determines if a verified user can perform a specific action. Common specifications like JWT, OAuth, and OAuth2 handle these tasks. 

The choice of authentication method depends on the balance between the required security level and ease of implementation and maintenance. OAuth provides scalability and excellent user experience but requires more effort for implementation and maintenance. OpenID can supplement OAuth by verifying a client’s identity and profile through the authorization server.

Query, Filter, Sorting, and Pagination

As your database grows, data retrieval may become slower. To mitigate this, implement caching, pagination, sorting and filtering. 

Sorting organizes data according to specific conditions, while pagination decides how much data to display and when. These features improve processing time, response time, and security. 

Filtering in APIs narrows down result sets based on certain criteria, improving API performance and reducing network data transmission. You can implement sorting, filtering, and pagination in different ways depending on the API type (e.g., using path parameters in REST APIs).

Caching for performance improvements

Caching stores frequently requested data in a secondary store, reducing calls to the primary database. This strategy enhances data retrieval speed and reduces request costs. Tools like Memcached and Redis can assist in this process. 

Depending on where you store the cache, you can use client caching or server caching. While client caching improves client and server efficiency by storing routine requests locally, server caching reduces server load by storing repeated calls in a cache.

REST provides simpler caching mechanisms. With the GraphQL API and the gRPC API, developers must spend more time on caching.

Error Handling

Effective error handling simplifies debugging by differentiating between client and server errors. Providing clear error codes, specifying the number of errors, explaining error causes, and distinguishing between general and domain errors are effective error-handling practices.


Validation confirms data correctness. Client-side validation usually involves prompt feedback for correction which is a plus for a product, while server-side validation is a must-have for ensuring security, data integrity and vulnerability protection. It includes tasks like validating required properties or defining property types.

Best Practices for Custom API Development

There are some best practices for API development that will help you to avoid well-known mistakes and improve the performance, security, and scalability of your product. But it’s essential to note that each case is unique and might require tailored and innovative solutions. 

1. Returning standard error codes

It’s crucial to handle errors gracefully to avoid confusion for API users. When an error occurs, returning an appropriate HTTP response code that indicates the specific type of error provides valuable information for API maintenance. Leaving errors unhandled could potentially disrupt the system, so it’s best to handle them without delay.

Error codes must be accompanied by informative messages to aid maintainers in troubleshooting issues effectively. However, it’s crucial to ensure that these error messages do not expose sensitive information that attackers could exploit to carry out malicious activities, such as data theft or system disruption.

2. Navigating API versioning 

To ensure smooth transitions and avoid disrupting clients, it’s essential to have different versions of the API whenever any changes are made. Versioning can be done using semantic versioning, such as 2.0.6 (indicating major version 2 and the sixth patch), which is a common practice in modern apps.

This approach allows us to gradually phase out older endpoints, rather than requiring everyone to move to the new API simultaneously. For instance, the v1 endpoint can remain active for users who prefer not to change, while the v2, with its exciting new features, caters to those who are ready to upgrade. This becomes especially crucial when your API is public, as versioning ensures compatibility with third-party apps that rely on your APIs.

By implementing versioning, a web API can clearly indicate the features and resources it offers, and client applications can make requests directed at specific versions of these features or resources. 

3. Crafting accurate documentation for APIs

The API documentation educates developers on how to use your APIs and where to start. This is necessary both for developers who will integrate your APIs, and for your team in case of software modernization

If your APIs are documented in detail, it’s easier to increase awareness and adoption of the API and decrease the time and costs of onboarding both remote and in-house developers. At the same time, any internal team can tap into API documentation to understand applied methods, resources, requests, and responses, which will simplify maintenance and updates.

You need to provide concise tutorials to aid developers in a quick start, create a comprehensive glossary defining API terms, and ensure that resources and methods are explained in a user-friendly manner. List all project terms to unify understanding among end users (developers), allowing them to grasp concepts like URLs and URIs, even with limited technical knowledge.

MobiDev API Development Case Studies 

The usage of best API development practices can be easily seen and assessed in MobiDev’s example. Below, you will find a few cases from our experience.

Case Study #1. Building a SaaS Platform with Complex API Integration

discover.swiss is a SaaS platform that relies on API integration to aggregate and standardize data from service providers of different sizes and share it across the network. Platform users are tourists who can see a unified picture of local travel spots and destinations in partner apps that are using the API.

Key tech challenges:

  • Create a complex  “API as a Service” ecosystem
  • Ensure data standardization for a single system

Create a complex “API as a Service” ecosystem

The developers needed to build a solution architecture that would allow the system to interact with various data resources and turn these data into structured information for the end user. After a detailed analysis of requirements, REST architecture was chosen.

REST APIs assist in aggregating multiple data points and turning them into structured information about tourist spots and activities. This information can be displayed in a common format in the front end of the tourist service providers. With the large tourist management systems providing information on one side and local service providers on the other, the business needs are all covered via the connection established with the API.

Obtaining data from partner services and data unification was one of the key challenges of the project. We had to create a system that would make it possible to add new partner services with a minimum of changes. For this, we created a scalable importing data platform that includes such things as a complex duplicate searching mechanism which is looking for duplicates from different sources and merging them. Also, we built an access mechanism responsible for managing access to individual data units.

vladyslav hlushkov .net team lead

Vladyslav Hlushkov

.Net Team Leader

Ensure data standardization for a single system

The project concept for this platform is based on the ecosystem approach and its scalability. New companies are constantly being added. Dedicated algorithms keep the aggregated information precise and unified. To achieve data standardization, the system concept relies on schema.org approved data structure definitions. Processing an array of data coming from different sources is possible by using storage queues. This allows the database load to be balanced and distributed.

We also relied on Azure Functions to build the API, process the data and ensure seamless integration between the essential parts of the platform.

Thanks to the cooperation with MobiDev, we were able to meet our high demands for a backend service quality platform for Swiss tourism. MobiDev convinced us with their excellent software development skills, their solution-oriented and imaginative contributions, and very reliable and high-quality services.

Jon Erni

CEO of discover.swiss

Case Study #2: Ensuring Real-Time Client-Server Communication for Taxi Booking Application 

The project is a taxi booking service that combines three solutions in a single suite: a native tablet-optimized Android app for drivers, a dispatch panel, and a native iOS app available to customers. Clients had strict deadlines, which we met by combining classical and innovative development approaches.

Key tech challenges:

  • Provide the solution within strict deadlines
  • Ensure effective real-time communication between all parts of the system

Provide the solution within strict deadlines

The solution had to be ready for production in three months, so this had a significant impact on the choice of development tools and approaches. To enable swift connection of all project components, we opted for REST API, which is both easy to develop and integrate. 

Relying on the experience of our engineers and proven technologies, we managed to deliver the product on time and meet all the technical requirements of customers.

Ensure effective real-time communication between all parts of the system

Although REST was the most suitable approach for this project, it had one notable limitation: it didn’t support real-time communication that would enable a continuous connection between the client and the server for fast data exchange. 

As it was crucial to maintain identical ride statuses across all sub-applications, the development team had to incorporate a third-party PaaS service called PubNub for real-time notifications and display of taxis on the map, order status updates, and more.

To ensure that ride states are accurately maintained, all communication between the apps is routed through the backend, which serves as the repository of records. The applications are only able to transmit requests to the backend via HTTP, with the backend subsequently utilizing PubNub to send notifications.

The application was installed by more than 1200 unique users within 2 weeks after its release.

We appreciate the team being very proactive in assuring that the technology was ready to go for launch. Roman was great to work with! His understanding and years of experience in software development are evident in his work. Eugene was very easy to work with, clear, and prompt. He invests himself in his work and the final product is representative of this. Andrey was great. He was prompt, knowledgeable, and easy to work with. Finally, working with Alex, Anton and Kostya was a pleasant experience. MobiDev has really shown us their dedication. Thank You!

Samuel Krut

Platform сo-founder, COO

API Development Services at MobiDev 

If your business faces any API development challenges, the MobiDev team is here to help with:

  • Enabling data integration across multiple platforms via APIs
  • Integrating third-party tools via APIs
  • Implementing an ‘API as a product’ project 

We follow a consultative approach and ensure the delivered solution can be seamlessly integrated into your existing ecosystem while meeting your business goals and becoming a profitable investment for you in the long term. 

This is supported by the involvement of business analysts to study your business case and clearly define its requirements. Then our tech experts create an effective architecture keeping these requirements in mind.

We provide both application modernization services and new product development services. Contact us below or book a call with a MobiDev expert to discuss your project needs.

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