WebTransport is almost here to allow UDP-like exchange in the browser
13 comments
·November 5, 2025mehagar
We tested this against WebRTC data channels (which also uses UDP) and found that the congestion control algorithm used for WebTransport limits its use for videoconferencing. We'll probably look into it again if browsers start allowing this to be configured.
ktpsns
I wonder why they did not extend the existing websocket API. Now if you want to be HTTP/1 or HTTP/2 backward compatible, you have to add another abstraction ontop of these two because WebTransports is HTTP/3 only.
chrismorgan
They’re pretty wildly incompatible in an API sense. One provides a single reliable bidirectional stream. The other provides arbitrarily many unreliable and reliable unidirectional and bidirectional streams, according to your own orchestration.
It’s like saying “I had a violin, why didn’t they make this new ‘orchestra’ thing behave the same way?”
If you’re willing to limit yourself to a single reliable bidirectional stream, abstracting over both WebTransport and WebSocket will be easy.
advisedwang
There is a proposal to do this: https://datatracker.ietf.org/doc/html/draft-ietf-webtrans-ht...
silverwind
Yeah, I don't see this or HTTP/3 gaining any widespread adoption because HTTP/3 needs obscure DNS records and messing with firewalls.
CharlesW
I can't find 2025 stats, but HTTP/3 adoption was already widespread two years ago. https://blog.apnic.net/2023/09/25/why-http-3-is-eating-the-w...
kaoD
HTTP/3 does not need obscure DNS records (but it's greatly enhanced by them).
Messing with firewalls in what way?
baggy_trough
All it really needs is a UDP port 443 hole punch. The DNS stuff is an optional optimization.
I think WebTransport is cool.
What worries me is that some people involved in standardisation seem to be of the opinion that WebTransport supersedes WebSocket. WS has become my go-to transport when I just need to be able to reliably send messages back and forth, whether or not the web is involved at all, and I don't see WebTransport as a replacement for that use case. I hope WS sticks around forever.
Also, it's messed up that WT is only available in HTTPS. There are so many cool use cases for web technologies in local contexts where HTTPS is not a practical option, it's a shame most new technologies are arbitrarily banned from those use cases.