Please excuse my ignorance of coding and programming in advanced.
I know OSBuddy originally came out around 2011-2012ish timeframe but obviously hindsight is 20/20
Are 3rd Party Clients allowed in 2004scape? Is it even possible for someone to create a client like this for 2004scape? I would assume it is if someone did it with RS2.
Third-party clients are not allowed to be used on Lost City servers. They are of course possible to create in theory, but they would be difficult to maintain.
OSBuddy in particular has an extremely storied history, very tightly intertwined with the cheating and botting scene.
The lineage of OSBuddy starts with an RS2 bot client (one of the best) called RSBuddy. In 2011 RSBuddy was shut down, and the following year it returned as a legitimate 3rd-party client for RS2.
Shortly after OSRS came out in 2013, some of the same developers released a 3rd-party client called Orion under the RSBuddy brand. There were some controversies around the Orion client and it was rebranded to OSBuddy in 2014 before it eventually shut down in 2023.
The modern concept of RuneScape “helper” clients for legitmate use was actually pioneered by the same people who made the bot clients 
and now you have RuneLite! Before these, all we had was SwiftSwitch…
Thank you for coming to my Ted talk!
Lol thanks for the history lesson and outlining the rules on this. I really only enjoy the QOL options that came with 3rd party clients like zoom, animation smoothing, increased fps, etc. but was just curious how that would work, if it would be rule breaking, or if it would be enforced if someone did that outside of the lostcity client.
Swiftswitch #1
Give us mIRC back. 
Swiftswift/ swiftkit style tool kits aren’t allowed? They don’t interact with the game client/code at all. Just useful tools like hiscores lookup, skill calcs, etc? How would they be hard to maintain? @branon
I would like the classic swiftkit eliteswitch clients with just highscores look up and IRC chat for clans
You are welcome 
I enjoy those features to an extent as well, but ultimately they unbalance the game and encourage a QoL arms race. These types of things start to look a lot like cheat clients in their later stages.
It is rulebreaking to use 3rd-party clients and we will enforce the rule. This isn’t written down on the rules page currently but I can change that. For now it’s left up to common sense (asking the question is smart too).
Cheat clients are not undetectable and we’re aware of those which have been used in the past. We banned the accounts that used them!
Oh! Sorry I got carried away reminiscing.
While modifying the game client is not allowed, SwiftSwitch-style toolkits are fine, I only know of this one: GitHub - Operativekiwi/2004scape-extension
This is not an endorsement and you should always be very cautious when installing web browser extensions!