web-echo service allows you to easily define on the fly JSON recorders which can be fed by remote services using either the dynamically generated webhook or the websockets you've provided. Then, at any time you can check what have been sent by the configured remote services. Check the swagger API specification for more information.
It has been deployed on https://mapland.fr/echo
Thanks to coursier from @alxarchambault, this application is quite easy to start, just execute :
cs launch fr.janalyse::web-echo:1.2.1
|Listening network interface
|Add a prefix to all defined routes
|How this service is known from outside
|Where data is stored