Yes, there are some public browser client projects you can find on GitHub/OTLand.
The most recent/useful option is probably OTClient Redemption / Mehah for web browsers:
OTClient for Web Browsers (https://otland.net/threads/otclient-for-web-browsers.290165/)
There are also some older projects, for example:
GitHub - jo3bingham/TibiaFlashClient: Decompiled sources of Cipsoft's Tibia Flash Client (https://github.com/jo3bingham/TibiaFlashClient)
But this one is very old.
You may also find other open-source browser clients on GitHub. Some are made for 9.50 a 11.48a+, but with some work and AI help, they can probably be adapted to 8.60.
Personally, I think the best option is to use the Mehah web version, because it is newer and has more things updated.