How to build a FiveM resource for characters

Create a resource on your server (e.g. mc_website_api) with this in server.lua:

SetHttpHandler(function(req, res)
    res.writeHead(200, {
        ['Content-Type'] = 'application/json',
        ['Access-Control-Allow-Origin'] = '*'
    })
    local players = {}
    for _, src in ipairs(GetPlayers()) do
        table.insert(players, {
            id   = src,
            name = GetPlayerName(src)
        })
    end
    res.send(json.encode({
        players = players,
        count   = #players
    }))
end)

Then set the Custom API URL above to http://your-ip:30120/mc_website_api. For character data, query your database inside that handler using oxmysql or mysql-async and return character fields like name, job, money, etc.