System Integration and API Development

In most companies data lives in several programs: requests in the CRM, payments in a payment service, stock in the warehouse system, documents in the accounting system. While the systems are not connected, employees move data by hand: copy orders, reconcile payments, forward statuses to customers. This is slow, expensive and error-prone.

Integration of information systems ties them into one process. An order from the website goes to the CRM on its own, a payment updates the status automatically, documents are generated without a manager, and the customer sees current information in their personal account. Employees stop being data couriers and do work that needs a person.

An API (application programming interface) is an agreement on how one program can ask another to do something or return data. For example, a website creates a payment through the payment service’s API, and a CRM learns stock levels through the warehouse system’s API. API integration is setting up this conversation between systems: which requests to send, what data to expect in response and what to do if no response comes.

A good integration is invisible: data simply appears where it is needed, at the right moment and without errors. A bad one reminds you of itself every day with duplicates, mismatches and manual fixes.

• Payment systems: accepting payments on the website and in the app, refunds, recurring payments, matching payments with orders.
• CRM: passing requests and orders, updating deal statuses, synchronising customers and contacts.
• Accounting and warehouse systems: stock, prices, documents, exchange of orders and payments.
• Delivery and logistics: shipping cost calculation, creating shipments, tracking statuses.
• Websites, personal accounts and mobile apps: shared data for every channel.
• Messengers, email and telephony: notifications for customers and staff, request handling.
• Cloud services: storage, analytics, mailing and authentication services.
• Language models (LLM): connecting AI to company data for document search, request processing and help for employees.

An example from our portfolio is the IntraLink corporate portal: new employees are added to corporate groups and chats automatically, and request data is collected for analytics.

Integration does not always mean connecting via API. We choose the method for the task and the capabilities of the systems.

API integration

Systems exchange data through a programming interface: one sends a request and the other replies. This is the most flexible and reliable method when both systems have a documented API. Most often it is a REST API, less often GraphQL, or SOAP in older enterprise systems.

Webhooks

A system reports an event itself, such as a new payment, a status change or a new order, by sending a request to a predefined address. Webhooks give real-time reaction without constant polling.

Scheduled synchronisation

Data is exported and imported at set intervals: every few minutes, hourly or daily. It suits large volumes and systems without events, for example updating a catalogue and stock levels.

Queues and an integration layer

When there are many systems, we build an intermediate integration service: it receives data from every system, converts formats, puts tasks into queues and retries failed deliveries. One unavailable system then does not stop the whole process, and adding a new integration is easier.

File exchange

If a system has no API, we exchange files on a schedule through secure storage. It is less convenient but reliable, and sometimes the only option for legacy systems.

If your system needs its own API, for a mobile app, partners or other company systems, we design and build it:

• REST API or GraphQL in Python and FastAPI;
• OpenAPI documentation: partners and other teams connect without long email threads;
• OAuth 2.0 authorisation and per-key permissions;
• API versioning, so changes do not break clients that are already connected;
• rate limits and request logging.

An integration that silently loses data is worse than manual work. So we build in:

• retries when an external system is temporarily unavailable;
• duplicate protection: resending does not create a second order or a second payment;
• an exchange log: you can see what data was sent, when and with what result;
• monitoring and error alerts, to learn about failures before customers do;
• isolation: calls to each external system live in a separate module, and changes to its API do not affect the rest.

1. Discovery: we study the processes, systems and their documentation and determine which system is the source of each kind of data.
2. Exchange design: we describe what data is sent, in what format and how often, and what to do on errors.
3. Development: we write integration modules or an intermediate service.
4. Testing: we check the exchange on test environments and copies of data, including failures and retries.
5. Launch and monitoring: we turn the exchange on and watch the first days of operation.
6. Support: we monitor stability and update integrations when external systems change.

• An order from the website: the order is created on the website, goes to the CRM, reserves goods in the warehouse system, creates a shipment with the delivery service, and the customer gets a message with a tracking number.
• A payment: the payment service reports a successful payment, the order status changes automatically, the accounting system gets data for documents, and the manager does not have to reconcile bank statements.
• An employee request: an employee submits a request on the corporate portal, it goes to the person in charge, and status updates arrive in the work chat.
• A partner account: prices, stock and documents come from the accounting system, and orders from the account go back without manual entry.

Language models are useful to a business when they work with its own data. A typical setup: documents, policies and the knowledge base are indexed, the system finds the relevant passages for an employee’s question and passes them to the model, and the model writes an answer with links to the sources. In the same way models process incoming emails and requests: they identify the topic, extract details and pass them to the right system.

We design such integrations so that the model receives only the data a task needs, and access to documents follows the employee’s permissions.

Connecting one system starts at ₽200K, integrating several systems with data synchronisation starts at ₽1.3M. The cost depends on the quality of the external systems’ documentation, the volume and frequency of exchange, response time requirements and the number of error-handling scenarios.

It often pays to integrate step by step: first connect the system with the biggest effect, such as payments or the CRM, and add the others on top of a working exchange. We write routine code and tests with AI tools, so timelines and costs are lower than with fully manual development.

• Reliability by default: retries, duplicate protection, logging and monitoring are part of the work.
• Developers, not configurators: if there is no ready connector, we write our own.
• 6-month warranty on our work.

Describe which systems need to be connected in the form below, and we will suggest an integration method and an estimate.