I’m a huge Yaws fan for a couple of reasons.

Firstly, because of the Yaws creators. They are rockstars:

• Claes Wikström, father of ETS/DETS/Mnesia
• Steve Vinoski, author of Designing for Scalability with Erlang/OTP

These guys are not only brilliant but also very friendly and helpful. They are true professionals who know what they’re doing.

Secondly, because of the Yaws users. Yaws has been used in production for years at WhatsApp (proof) and Klarna (proof). These billion-dollar companies bet on Yaws. Why shouldn’t we?

And last but not least, my own experience with it. In short, Yaws is good enough. It’s not perfect by any means. Its community is not as big as Cowboy’s. It lacks quite a few of the features you get with Phoenix out of the box. But Yaws works for me, offering a nice balance between low-level control and productivity.

Yaws was one of the ‘old days’ erlang web servers. Great to work in, was quite fun, however it was also not very fast, but it was a full framework more along the lines of Phoenix (or even more). I’ve used it decently like a decade ago. ^.^

Cowboy is a very low level network dispatcher, not just for web, anything to do with the network really. Phoenix is built on cowboy. Phoenix is also much faster growing because of Elixir supporting it.

Comparing cowboy and yaws makes no sense, different stacks; comparing yaws and phoenix would make more sense.

Oh wow misultin, Chicago Boss, all kinds of old erlang web things are coming back to me, I’ve at least messed with them all years ago.

But yes, misultin was on the same vein as cowboy, a low level network dispatcher, but not near as fast as cowboy itself. Misultin was actually a newer incarnation of an even older network dispatch that I forgot the name of, but also started with an m. Chicago Boss was a ‘full fledged framework’, even more so than Phoenix and Yaws, very opinionated but very easy to get stuff done in it.

Someone really should rewrite Chicago Boss on top of phoenix! ^.^

As in huge, Yaws had templating engines, data storage, everything you need. Cowboy is just a little network dispatcher, even the http ranch handling is just an add-on on it.

The difference between Yaws and Cowboy is along the lines of the difference between, say, Apache and Puma. One is a full-blown traditional web server daemon that handles traditional websites (but happens to be able to be integrated into other Erlang applications). The other is a component to allow an Erlang application to listen for and accept HTTP requests.

Basically:

• If you need to setup a server to host a traditional website (static HTML pages, or maybe server-side includes or CGI), then Yaws is the right fit
• If you need to give your application the ability to communicate with clients over HTTP, then Cowboy is the right fit (Yaws can work here, but unless you want to write a Yaws adapter for Plug or forsake Plug entirely, it probably ain’t happening in an Elixir application)

Even equating Yaws to something as immense and comprehensive as Phoenix dramatically undersells the sort of stuff Yaws can do.

While we’re on the topic of Erlang web servers, there’s also MochiWeb.