Hello, i can offer application written in Java (cross-platform, not JavaScript).
I have experience developing multi-threaded fetching/execution using Proxy connections in Java previously. Already have some code base for this project.
Application is packaged as executable and can be run on any PC or on web server (VPS).
Configuration is setup via file or UI (as needed). UI can/may display current progress of execution.
UI Could be GUI (Forms) or Console like with progress.
Full source code provided via private GIT repository and documentation how to run and setup application.
Endpoint sites (execution points) need clarification and examples.
Contact me fore more details.