API & Software Dev

Every modern digital ecosystem is made of parts: a website, a booking engine, a CRM, a property management system, a payment gateway, a data analytics platform, a clinical information system. Each part may work well in isolation. The real value, however, is created when these parts communicate seamlessly — exchanging data in real time, without friction and without manual intervention.

This is the domain of API integration and custom software development. The gap between organisations that have done it well and those that have not is immediately visible: in the quality of the user experience, in the efficiency of internal operations, and in the ability to scale services without rebuilding from scratch every time something needs to change.

Esario has been designing and implementing API integrations and custom software solutions for over twenty years, with deep sector experience in Hotels, E-Commerce, Finance and Bio-Medical. The combination of technical expertise and domain knowledge is what allows Esario to deliver integrations that are not only technically correct but genuinely useful — aligned with the business logic of the sector, the needs of the users and the constraints of the regulatory environment in which each client operates.

Server-side API integration

Server-side API integration connects a client's web infrastructure with external services and data sources at the server level, before the response is delivered to the user's browser. Esario's developers are expert in implementing both principal architectural styles used in production environments today.

SOAP-based web services

A structured XML protocol exchanging information over HTTP, offering a high degree of formalisation and built-in error handling that makes it particularly suited to enterprise environments and regulated sectors where transactional reliability and auditability are paramount. Esario has extensive experience writing the custom interfaces required to connect existing websites and applications to SOAP-based services — particularly in the hospitality sector, where PMS, CRS and Channel Manager providers have historically used SOAP as their primary integration protocol.

RESTful web services

Following the Representational State Transfer architectural style — communicating over standard HTTP in a way that is lightweight, stateless and straightforward to integrate. REST remains the dominant approach for public and partner-facing APIs. Esario designs, implements and maintains RESTful integrations across a wide range of service providers and platforms, developing custom interfaces where standard connectors do not exist or do not meet the client's specific requirements.

Client-side API integration

Client-side API integration exchanges data directly between the user's browser and external services — enabling a website to combine its own content with functionality and data from third-party platforms without requiring a server round-trip.

For hotel websites, this means integrating a booking engine directly into the page so that the booking experience is seamless and consistent with the rest of the site, rather than launching in an external window that interrupts the user journey and undermines brand consistency. It means embedding TripAdvisor reviews, Google Maps, real-time weather forecasts and live availability calendars as native elements of the page rather than disconnected external widgets.

Esario selects, configures and, where necessary, develops custom versions of client-side API integrations tailored to the specific needs of each client — ensuring both functional correctness and alignment with the UX and information architecture of the digital environment they serve.

Tourism and hospitality: deep sector integration experience

The hospitality sector presents some of the most complex API integration challenges in the digital industry. A hotel website sits at the intersection of multiple systems that must communicate in real time: the Internet Booking Engine, the Property Management System, the Central Reservation System, the Channel Manager, the revenue management platform and the customer data infrastructure.

Esario has built and maintained integrations across all of these system categories — developing the custom code necessary to connect booking engines to hotel websites at a level of integration that goes beyond embedding an external iframe: full inline integration that preserves the brand experience, communicates correctly with the underlying PMS and CRS, and delivers the booking data in the format each downstream system requires.

Custom software development: Bio-Medical

Beyond API integration, Esario has developed custom software solutions for clients in the Bio-Medical sector, where the requirements for precision, regulatory compliance and the handling of sensitive data demand a development approach that is fundamentally different from standard commercial software projects.

Bio-Medical software development at Esario is characterised by close collaboration with clinical and scientific professionals to ensure that the functional logic of the software reflects the actual workflows and decision-making processes of the domain; rigorous attention to data security and privacy in compliance with applicable health data regulations; development methodologies that produce auditable, maintainable and well-documented code; and user interface design grounded in the same UX principles Esario applies across all its services.

Custom Bio-Medical software developed by Esario includes systems for the management of clinical data, tools for the processing and visualisation of diagnostic information, and platforms for the structured exchange of information between healthcare professionals.

The evolving API landscape in 2026

REST APIs still dominate but no longer monopolise the architectural landscape. GraphQL has matured significantly for flexible data fetching, giving clients precise control over data retrieval and measurably improving mobile performance — enterprise usage has grown more than 340% since 2023, and nearly half of new API projects now consider GraphQL first. gRPC has emerged as the protocol of choice for internal microservices communications, with substantial performance advantages for high-frequency, low-latency use cases.

According to Gartner, by 2026 more than 30% of the increase in API demand will come from AI tools using Large Language Models. APIs are no longer built solely for application integration: they are becoming AI-consumable capabilities, powering intelligent workflows, agent economies and real-time digital decision-making. API design decisions made today will directly determine whether a digital system can be extended with AI capabilities tomorrow, or whether it will require a complete rearchitecture.

Security has become the most critical non-functional dimension of API design. The growth in API surface area has made APIs one of the primary attack vectors in modern cybersecurity. Esario applies API security best practices at every stage: authentication and authorisation design, rate limiting, input validation, secure credential management and monitoring for anomalous usage patterns.

API integration and Artificial Intelligence

In integration development, AI-assisted coding tools accelerate the generation of interface code, documentation and test suites — reducing the time required to implement and validate complex integrations while improving consistency and reducing the risk of human error in repetitive tasks.

In API monitoring and operations, AI is used to monitor APIs, optimise microservices workflows and predict system failures before they occur — enabling predictive maintenance and automated issue resolution that reduce downtime and protect the quality of the services that depend on these integrations.

In the design of AI-powered digital systems, well-structured APIs are the prerequisite. A hotel recommendation engine, a clinical decision support tool or a personalised e-commerce experience powered by AI is only as good as the data it can access and the speed at which it can access it. Esario's expertise in information architecture and API design means that the semantic structure and the technical access layer are designed together — producing systems where the AI has access to the right data, in the right format, at the right time.