I have been looking for free or paid json data feeds on currencies for long.
I have come across:
The problem is that I really need millisecond based updates.
Can someone advice me on the way forward?
There are so called mid-rate reference price providers who eventually offer newsfeeds, however, the answer will very likely be a commercial service.
The otehr path would be to contact liquidity providers and / or exchanges directly and ask for API / feed access , which again , will most likely be a commercial service.
https://Polygon.io has FX real-time and historic APIs.
WebSockets for real-time updates, and RESTful API for historic data.