Utility module for making direct game join links easier https://devforum.roblox.com/t/1904069

GameJoinUrlUtil.luau

--!strict

-- GameJoinUrlUtil
-- A utility module for generation join links for any game
-- with url enocoding and launchdata encoding included
-- @Kalrnlo
-- 30/11/2023

local HTTPService = game:GetService("HttpService")

local StartUrlFormat = "https://www.roblox.com/games/start?placeId=%d"
local WebsiteBypassUrlFormat = "roblox://placeId=%d"
local LaunchDataBypassUrlFormat = `{WebsiteBypassUrlFormat}&launchdata=%s`
-- Put the encoded BypassURl as the first string when formatting
-- Put the encoded StartUrl as the second string when formatting
local AppsFlyerUrlFormat = "ro.blox.com/Ebh5?af_dp=%s&af_web_dp=%s"
local LaunchDataStartUrlFormat = `{StartUrlFormat}&launchdata=%s`

-- Taken from:
-- https://devforum.roblox.com/t/233570/2
local function DecodeCharacter(hex: string)
	return string.char(tonumber(hex, 16) :: any)
end

local GameJoinUrlUtil = {}

function GameJoinUrlUtil.EncodeLaunchData(LaunchData: string): string
	-- using string.len as #LaunchData generated faulty results
	assert(string.len(LaunchData) < 200, "LaunchData encoded exceeds 200 character limit")
	return HTTPService:UrlEncode(LaunchData)
end

function GameJoinUrlUtil.MakeAppsFlyerUrl(PlaceId: number, LaunchData: string)
	local StartUrl: string, BypassUrl: string

	if LaunchData then
		local LaunchData = GameJoinUrlUtil.EncodeLaunchData(LaunchData)

		BypassUrl = string.format(LaunchDataBypassUrlFormat, PlaceId, LaunchData)
		StartUrl = string.format(LaunchDataStartUrlFormat, PlaceId, LaunchData)
	else
		BypassUrl = string.format(WebsiteBypassUrlFormat, PlaceId)
		StartUrl = string.format(StartUrlFormat, PlaceId)
	end
	return string.format(AppsFlyerUrlFormat, BypassUrl, StartUrl)
end

function GameJoinUrlUtil.MakeStartUrl(PlaceId: number, LaunchData: string)
	if LaunchData then
		local LaunchData = GameJoinUrlUtil.EncodeLaunchData(LaunchData)
		return string.format(LaunchDataStartUrlFormat, PlaceId, LaunchData)
	else
		return string.format(StartUrlFormat, PlaceId)
	end
end

function GameJoinUrlUtil.DecodeUrl(Url: string)
	local Output, t = string.gsub(Url, "%%(%x%x)", DecodeCharacter)
	return Output
end

return GameJoinUrlUtil