It used to be opera. These days though, pretty much every browser is based on chrome, chromium or Firefox. To support modern websites as you specified is very complex, especially when taking into account security and performance. I don’t know of any lesser known browser engines if you expect to render common websites and support video, sound, animations and so on.

as usually you have to go with privacy respecting open source browsers, cause those dont get pointless feature integrations. you havent specified the platform so:

• for android: ironfox, fennec, helium
• for pc: ungoogled chromium, librewolf, helium

you should also look around on alternativeto.net

Literally none without jank. Javascript and HTML5 are monsters and it just isn’t possible to get a universally flawless experience without them.

Your best bet is if you’re willing to give up a significant amount of fidelity (and images). https://en.wikipedia.org/wiki/Lynx_(web_browser)

We’re no longer just rendering text anymore. It’s at the point webpages are basically compiled in real time.

It’s no longer possible unless you give up a lot

If the “literally any modern website” part is a hard requirement, then I would suggest to go for a fork of modern mainstream browsers with strong privacy/adblocking features. The justification for this is that browser engines can only get so light in terms of complexity and still support modern sites, but sites themselves can be made to be less resource demanding on the browser by selectively blocking unwanted elements. Adblocking is the obvious, blocking unwanted JavaScript would likely be the next best bang for the buck, but even clearing the cache after each session can make the browser feel faster if your bottleneck is memory/cpu instead of the network.

Pale Moon Portable

give it a shot , its opensource and very light weight

Whatever’s the most debloated version of firefox or chrome.

You will not get all websites on something thats light weight. Web browsers are basically mini operating systems at this point.

Lynx

A “minimum RAM, maximum screen real estate” browser?

I’ve used many browser forks. But I needed one for that specific constraint, and my search landed me on Zen Browser.

However, keep in mind that extensions are heavy. If you need (for example) adblocking, then a browser integrating an Adblock engine natively is best.

For what platform?

😂

I wish this existed :'(

Realistically speaking, the most lightweight browser capable of using modern websites and not just being reskinned Firefox or some Chromium-based browser is Luakit.

It uses Webkit for rendering and Lua for configuration – but be aware, the configuration is absurdly overcomplicated and complex and extremely poor documented.

https://luakit.github.io/

Even Chromium browsers, which is unfortunately the standard most websites are built around, don’t support everything that well. Can’t be done.

There is a Waterfox Portable, but lately I haven’t been able to get it to use Video Calls on things such as Discord or Zoom (it worked in the past, might be a current update issue).

Personally, I prefer browsers that by default disable most of the stuff on modern websites unless I explicitly enable it.

It’s been over a decade since I’ve visited a public website that ran exactly the way the owner planned on my browser — but that’s a good thing. I browse for the most part without ads or scripts or tracking. It’s fast, reasonably secure, and when a page fails to load what I’m expecting, I have to make the decision on whether it’s worth lowering my privacy, security and resource posture to make it work.

One solution that works pretty well is to use a web gateway that takes any website and makes it mostly functional on any browser back to the original Netscape Communicator and NCSA Mosaic. That way, you can use a very lightweight browser and let a server somewhere do the heavy lifting.