The framework your RedM server is built on.

Get the core once, then read everything about a player from one object.

local RSGCore = exports['rsg-core']:GetCoreObject()

local Player = RSGCore.Functions.GetPlayer(src)
if not Player then return end

local data = Player.PlayerData
-- data.citizenid, data.charinfo, data.job,
-- data.gang, data.money, data.metadata ...
print(data.charinfo.firstname, data.job.label)

Four money types. Failed payments return false, so you never hand out goods for free.

-- cash, gold, bank, bloodmoney
if Player.Functions.RemoveMoney('cash', 12, 'general-store') then
    exports['rsg-inventory']:AddItem(src, 'bread', 1)
else
    RSGCore.Functions.Notify(src, 'Not enough cash', 'error')
end

Players can hold several jobs and switch between them. Built into the core.

local ok, reason = RSGCore.Functions.AddPlayerJob(src, 'sheriff', 1)
if not ok then
    -- invalid_job, invalid_grade, max_jobs ...
end

local held, grade = RSGCore.Functions.HasPlayerJob(src, 'sheriff')
local jobs = RSGCore.Functions.GetPlayerJobs(src)

Check the space first, then add. Notifications and logging happen for you.

if exports['rsg-inventory']:CanAddItem(src, 'resource_wood', 5) then
    exports['rsg-inventory']:AddItem(
        src, 'resource_wood', 5, nil, nil, 'woodcutting'
    )
end

-- stashes and shops use the same exports
exports['rsg-inventory']:OpenInventory(src, 'sheriff-stash', {
    maxweight = 100000, slots = 50
})

Add interactions to peds, props, models and zones, limited by job, gang or item.

exports['rsg-target']:addLocalEntity(ped, {
  {
    name = 'trader_talk',
    icon = 'fa-solid fa-comments',
    label = 'Talk to trader',
    distance = 2.0,
    groups = { trader = 0 },
    onSelect = function(data) -- ... end,
  }
})

Ask the server a question from the client and wait for the answer.

-- server
RSGCore.Functions.CreateCallback('res:server:getThing', function(source, cb)
    cb(result)
end)

-- client
local result = RSGCore.Functions.AwaitCallback('res:server:getThing', 5000)