The most common cause of slow REST APIs is not the server, it is the amount of data transferred. Projection reduces response size to what the client actually needs. Streaming transfers large datasets without memory overhead. Compression cuts the network load roughly in half. HTTP caching eliminates redundant requests entirely.
Good API documentation is not what gets generated automatically from OpenAPI comments. It is what enables an external developer to make their first successful API call within 15 minutes and then keep integrating on their own, without opening a support ticket.
The choice between OpenAPI-First and Code-First is not a technical decision, it is an organizational one. It depends on team size, product maturity, number of consumers and synchronization requirements. This guide provides a structured decision framework, with concrete tooling recommendations for both approaches.
Error modeling is the neglected part of API design. RFC 9457 Problem Details, domain-specific error codes and polymorphic error schemas make the difference between an API where integrators have to guess what an error means and an API where errors are self-explanatory and machine-processable.
OpenAPI 3.1 is the industry standard for REST API documentation, yet many teams only use a fraction of its capabilities. This guide explains all the essential building blocks: from Info and Paths through Components and Schemas to Security and Callbacks, with complete practical YAML examples.
Choosing the wrong authentication method costs more than just security, it costs developer time on every single integration. API keys, bearer tokens, OAuth2 and HMAC signed requests each solve a different problem, and knowing the difference lets you make the right call before the first commit.
List endpoints are the most complex parts of a REST API: they must support pagination, filtering and sorting consistently without bloating the API surface. The difference between a well designed and a poorly designed list endpoint comes down to three decisions: cursor or offset, which filter parameters are allowed, and how the meta object informs consumers.
Network failures happen. Timeouts happen. What happens when a client retries a request because it never got a response? For idempotent methods: nothing bad. For POST: possibly a duplicate order, a duplicate record, or a duplicate charge. This article explains how to design REST APIs so that retries are safe.
Serializer Groups promise flexible JSON output without code duplication. In small projects they deliver on that promise. In grown APIs they become a hidden complexity driver that confuses new developers for hours and turns refactoring into a Sisyphean task.
Generating code from OpenAPI specifications sounds tempting, but in practice it often produces unreadable cruft that immediately needs manual patching. That defeats the whole point of generation. This article shows how to configure openapi-generator so the output code is maintainable, and why template overrides are the key to that.