Using the ABRA Flexi REST API opens up a wide range of possibilities for integrating the system with other applications and automating common processes. However, to ensure that your integration works reliably and efficiently, you need to follow certain rules and best practices. The right approach saves developers time, reduces the load on the system, and prevents unnecessary errors when working with data.

This article focuses on recommended best practices that will help you get the most out of the API – from query optimization, proper pagination, and retry strategies to working with error codes and understanding them. You will also learn how to avoid duplicates, how to work with limits, and why it is important to think about security and data consistency from the very start of your integration design.

Authentication is a fundamental element of security when working with the REST API. If it is not set up correctly, sensitive data may be leaked or the system may be accessed without authorization. It is therefore necessary to use secure methods for logging in and transferring data, and to avoid outdated or risky practices that could compromise the security of the entire integration.

Credentials (usernames, passwords, API tokens) are the key to your data. If they fall into the wrong hands, a serious security incident may occur. It is therefore necessary to handle them with the utmost care and to follow best practices that minimize the risk of leakage.

The goal is not to "download everything," but to quickly get exactly what you need, with minimal load on both the network and the server. Think about how you use the data: what you will actually display, how often it changes, whether you need to load it immediately, or whether part of it can be precomputed or cached. Well-designed queries and data flows shorten response times, conserve API limits, and increase the stability of the entire integration.

You do not have to download all the data again – it is more efficient to retrieve only the changes. Change feeds (Changes API) and push notifications (webhooks) serve this purpose. The Changes API is ideal for reliable delta synchronization driven by the client (polling + cursor), while webhooks are best for quick reaction to events without unnecessary polling. In practice, it is often best to combine both approaches.

Instead of downloading the entire record set on every synchronization, it is better to retrieve only what has actually changed. Delta export significantly reduces data transfers, lowers the load on the API and database, and speeds up the integration – especially for larger record sets or regular reporting.

When working with the REST API, do not run multiple identical requests at the same time. If this is overdone, the system becomes overloaded, and the result is usually slowdowns or error responses. We block excessive overloading as a last resort, and unblocking may need to be resolved with our support team.

It is therefore a good idea to work with parallel requests carefully and to spread calls out intelligently over time.

When communicating with the API, a situation may arise in which the server rejects further requests because it is currently overloaded. This typically manifests as the error code 429 – Too Many Requests.

In such a case, it is not advisable to retry the request immediately, as this would increase the load even more. The correct practice is to use so-called exponential backoff – that is, gradually increasing the waiting time between subsequent attempts.

Respect the daily request limit. The default limit for your license may differ depending on the volume purchased.

Correctly evaluating HTTP error codes is key to a reliable integration. Each code has its own meaning and helps distinguish whether the problem is on the client side (bad request, invalid data, missing permissions) or on the server side (temporary unavailability, internal error). This allows the application to respond correctly – either by fixing the data and resending the request, or by waiting and trying the action again later.

When writing data through the API, it is important to ensure that a repeated request is not processed multiple times and does not create duplicates. A typical situation occurs when a connection drops or a retry strategy is used – the client is not sure whether the request went through and sends it again. Without idempotency, multiple invoices, orders, or other documents could be created, which is a problem especially in accounting.

When integrating with the REST API, it is very useful to keep records of the requests sent and the responses received. Logs allow you to quickly find out why something is not working, what the API actually returned, or what request was sent to the server. Logging is also an invaluable aid when communicating with customer support – instead of a vague description such as "something went wrong," you have specific data at your disposal.

The API evolves over time – new fields are added, and sometimes the format or logic of a response changes. If your application is not prepared for this, it may stop working after a change. It is therefore important to write integrations so that they are resilient to changes, while also keeping track of API developments.

A quality integration is not just about calling the API correctly, but also about how easy it is to deploy, test, and maintain. Separating the test and production environments reduces the risk of errors, as does the right approach to data backups – it is better to handle those through the web interface than through the API.

Without ongoing visibility into how many API calls you make and how often, problems are detected too late. Basic monitoring helps you keep track of limits, tune performance, and prevent integration outages.

Following best practices when working with the ABRA Flexi REST API will help you build stable, secure, and long-term sustainable integrations. Whether it is query optimization, error handling, or secure handling of credentials, it always pays to invest in a sound design from the very beginning.

If you are not sure how to use the API in your specific scenario, or you need more detailed recommendations, you can arrange an individual consultation, where we will be happy to help you with the implementation.