No.  Common questions regarding limits:

Websites: We do not limit the sites you can access with the exception of IPv4.  With IPv4 you can access the domains you bought for, some whitelisted CDNs and some whitelisted IP testing websites.  You can however add as many domains as you wish.

Connections / threads: You can connect to the same proxy with an unlimited number of threads

Bandwidth: We do not limit bandwidth usage.  However if we notice abuse of this we may intervene.  Our proxies are not intended for streaming services such as Netflix.  All of our proxies have 1 gigabit or larger connections.

Number of proxies: You can create as many as you wish

IPv6 rotations: You can rotate your IPv6 proxies every second via the API

API requests: You can do as many requests as needed as long as it does not appear to be abusive or impacting the performance of our service (doing multiple requests for the same proxy in under a second for example.)