An integration flow segment is identified by receiving a start point and an end point in an integration flow in a web editor in a graphical user interface. The integration testing is simulated for the integration flow segment by providing a test payload in the web editor. A code segment corresponding to the integration flow segment is extracted. Based on the code segment, a runtime artifact is generated and deployed in a worker node hosting an integration runtime engine. The runtime artifact is loaded in a volatile memory corresponding to the worker node, and executed with the test payload in a worker node. The results of simulated integration testing are sent to the web editor. The runtime artifact is unloaded from the volatile memory. Results of the simulated integration testing are displayed at a visual proximity to sequence flows in the integration flow segment in the web editor.