[Update] February 12, 2026
Hi Creators,
We’re excited to announce the release of ReflectionService, a new service that allows you to programmatically inspect the Roblox engine’s API surface. You can use ReflectionService to create systems that depend on changes to the API surface and leverage information about the engine API, such as API inspection plugins to analyze and use new API releases and better instance class changing plugins for faster workflows in Studio.
How to Use ReflectionService
Currently, ReflectionService is focused on providing detailed information about Instances and their Properties. ReflectionService exposes three primary methods for retrieving this API information:
1. ReflectionService:GetClass(string className, ReflectionClassFilter filter = {})
- Pass in the name of an instance (e.g.,
"Part","MeshPart") to retrieve information about its instance hierarchy and access privileges. - Optional: The
filterargument can be used to refine the output, such as expanding the data returned or specifying the security context for access checks.
2. ReflectionService:GetClasses(ReflectionClassFilter filter = {})
- Returns information about all instances in the engine that are accessible to the current security context.
- Optional: Use the
filterargument to narrow the output or request expanded details.
3. ReflectionService:GetPropertiesOfClass(string className, ReflectionClassFilter filter = {})
- Pass in an instance name (e.g.,
"Part") to get comprehensive information about all its properties, including its data type, whether it is serialized (saved/loaded), and its access security level. - Optional: The
filterargument allows you to customize the details you receive.
You can browse full documentation for the service using this link.
Understanding Security Capabilities
ReflectionService filters the output from its methods using SecurityCapabilities. This bitset-like value describes the access a given script execution context has to certain functionality, including APIs.
By default, ReflectionService will only return instances and properties that are accessible according to the SecurityCapabilities assigned to the current script execution context (e.g., a Plugin, a ModuleScript, or a regular game script). This means the output will differ based on where the code is run.The filter argument allows you to modify the security context used for the query.
Limiting the Context (Zero Capabilities)
If you limit the context to include no capabilities, you’ll receive the subset of classes that are accessible in all security contexts.
local ReflectionService = game:GetService("ReflectionService")
-- Create a SecurityCapabilities object with no capabilities
local noCapabilities = SecurityCapabilities.new()
-- Get all classes accessible with no capabilities
local allClassesWithNoSecurity = ReflectionService:GetClasses({ Security = noCapabilities })
print("Total classes:", #allClasses)
Expanding the Context (All Capabilities)
If you expand the context to include all capabilities, you’ll receive virtually all classes and properties in the engine from ReflectionService, including all serialized classes and properties in the API.
local ReflectionService = game:GetService("ReflectionService")
-- Create a SecurityCapabilities object with all capabilities
local allCapabilities = SecurityCapabilities.new(table.unpack(Enum.SecurityCapability:GetEnumItems()))
-- Get all classes accessible with all capabilities
local allClasses = ReflectionService:GetClasses({ Security = allCapabilities })
print("Total classes:", #allClasses)
A Quick Example: The Instance Spawner Plugin
To demonstrate how to iterate over accessible classes, here is a small (and silly) plugin script. It’ll attempt to create one instance of every creatable class accessible to the plugin’s security context, all placed in a single folder in Workspace! (Plugin Link)
Plugin Script
local ReflectionService = game:GetService("ReflectionService")
local Workspace = game:GetService("Workspace")
local ChangeHistoryService = game:GetService("ChangeHistoryService")
local toolbar = plugin:CreateToolbar("ReflectionService Demo")
local createInstancesButton = toolbar:CreateButton(
"Create Instances",
"Create all instances accessible in the current security context",
"rbxassetid://14978048121"
)
createInstancesButton.ClickableWhenViewportHidden = true
local function onPluginButtonClicked()
-- Get all classes from ReflectionService in the current security context
local classes = ReflectionService:GetClasses()
-- Filter for creatable classes
local creatableClasses = {}
for _, classInfo in ipairs(classes) do
if classInfo.Permits and classInfo.Permits.New then
table.insert(creatableClasses, classInfo.Name)
end
end
table.sort(creatableClasses)
-- Create instances folder in Workspace
local instancesFolder = Instance.new("Folder")
instancesFolder.Name = "AllInstances_" .. os.time()
instancesFolder.Parent = Workspace
local createdCount = 0
local failedCount = 0
local currentY = 1.5 -- Track Y position for stacking instances with CFrame
-- Attempt to create one instance of each creatable class
for _, className in ipairs(creatableClasses) do
local success, instance = pcall(function()
return Instance.new(className)
end)
if success and instance then
local setSuccess, setError = pcall(function()
instance.Name = className
instance.Parent = instancesFolder
-- Check if instance has CFrame property and stack it on top of previous instances
local hasCFrame = false
pcall(function()
local _ = instance.CFrame
hasCFrame = true
end)
if hasCFrame then
local height = 2 -- Default height if we can't determine size
-- Try to get the actual size/height of the instance
if instance:IsA("BasePart") then
height = instance.Size.Y
else
local sizeSuccess, size = pcall(function()
return instance.Size
end)
if sizeSuccess and size then
height = size.Y
end
end
-- Set CFrame to stack on top
local newCFrame = CFrame.new(0, currentY + height / 2, 0)
local setCFrameSuccess = pcall(function()
instance.CFrame = newCFrame
end)
if setCFrameSuccess then
-- Update currentY for next instance
currentY = currentY + height
end
end
end)
if setSuccess then
createdCount = createdCount + 1
else
warn("Failed to set properties for instance of class: " .. className .. " - " .. tostring(setError))
failedCount = failedCount + 1
end
else
warn("Failed to create instance of class: " .. className)
failedCount = failedCount + 1
end
end
ChangeHistoryService:SetWaypoint(string.format("Created %d instances (%d failed)", createdCount, failedCount))
print(string.format("Created %d instances in Workspace.%s", createdCount, instancesFolder.Name))
end
createInstancesButton.Click:Connect(onPluginButtonClicked)
We look forward to seeing how you make the most of ReflectionService. Please share any feedback, suggestions, or questions you have.
Cheers,
The Roblox Engine Systems Team
