diff --git a/libcredit_mobile.lua b/libcredit_mobile.lua
new file mode 100644
index 0000000..eeae436
--- /dev/null
+++ b/libcredit_mobile.lua
@@ -0,0 +1,102 @@
+local M = {}
+
+local modem = peripheral.wrap("back")
+local SERVER_CHANNEL = 43
+
+local function sendRequestAndWaitForReply(messageTable, replyHandler, timeout)
+    timeout = timeout or 5
+
+    local replyChannel = math.random(1000, 9999)
+    modem.open(replyChannel) 
+    messageTable.replyChannel = replyChannel
+
+    local jsonMessage = textutils.serialiseJSON(messageTable)
+    modem.transmit(SERVER_CHANNEL, replyChannel, jsonMessage)
+
+    local startTime = os.clock()
+    local replyReceived = false
+    while os.clock() - startTime < timeout do
+        local event, side, channel, receivedReplyChannel, message, distance = os.pullEvent("modem_message")
+        if event == "modem_message" and channel == replyChannel then
+            local success, parsedReply = pcall(textutils.unserialiseJSON, message)
+            if success and type(parsedReply) == "table" then
+                replyHandler(parsedReply)
+                replyReceived = true
+                break 
+            end
+        end
+    end
+    modem.close(replyChannel) 
+
+    return replyReceived
+end
+
+function M.getCredit(username, callback)
+    local message = {
+        type = "getCredit",
+        user = username
+    }
+
+    return sendRequestAndWaitForReply(message, function(reply)
+        if reply.type == "creditResponse" and reply.user == username then
+            callback(reply.credit)
+        else
+
+            callback(nil)
+        end
+    end)
+end
+
+function M.addTransaction(username, amount, vendor, vendor_account, callback, timeout)
+
+    if type(amount) ~= "number" or amount <= 0 then
+        error("Amount must be a positive number.", 2)
+    end
+    if type(username) ~= "string" or #username == 0 then
+        error("Username must be a non-empty string.", 2)
+    end
+    if type(vendor) ~= "string" or #vendor == 0 then
+        error("Vendor must be a non-empty string.", 2)
+    end
+    if type(vendor_account) ~= "string" or #vendor_account == 0 then
+        error("Vendor account must be a non-empty string.", 2)
+    end
+    if type(callback) ~= "function" then
+        error("Callback must be a function.", 2)
+    end
+
+    if timeout and (type(timeout) ~= "number" or timeout <= 0) then
+        error("Timeout must be a positive number if provided.", 2)
+    end
+
+    local message = {
+        type = "addTransaction",
+        user = username,
+        amount = amount,
+        vendor = vendor,
+        vendor_account = vendor_account
+    }
+
+    return sendRequestAndWaitForReply(message, function(reply)
+
+        if reply.type == "transactionCompleted" and reply.transaction_id then
+            if reply.status == "success" then
+                callback(true, reply.newCredit) 
+            elseif reply.status == "failed" then
+
+                callback(false, reply.reason) 
+            elseif reply.status == "cancelled" then
+
+                callback(false, "cancelled") 
+            else
+
+                callback(false, "unknown_status")
+            end
+        else
+
+            callback(false, "unexpected_reply") 
+        end
+    end, timeout) 
+end
+
+return M
\ No newline at end of file