camel

Camel has been wiring enterprise systems together since 2007, and the reason it survived is 350-odd connectors you do not have to write yourself. It is an integration framework: it moves data between systems that were never designed to talk. A route reads from one place (a database, a Kafka topic, an FTP drop, an HTTP endpoint) and delivers somewhere else, with transformation and error handling in between. Routes are written in Java, YAML, or XML. Apache 2.0, free.

Deployment is flexible: Spring Boot, Quarkus, or standalone through the Camel CLI. Java is the hard requirement. Kaoto and Karavan give you visual route design if hand-writing the DSL is not your thing, and there is an MCP server now, so an AI assistant can work with your routes directly.

Free, entirely, with no paid tier from the project. Solo developers rarely need this. It earns its place once you have more than a handful of systems exchanging data and you are tired of bespoke glue scripts that fail silently at 3am.

The catch is weight and learning curve. Enterprise Integration Patterns are a real body of knowledge and Camel assumes you know them. For two or three simple integrations, a few scripts or an n8n workflow gets you there far faster. Camel pays off at scale and charges you upfront in understanding.