BootStrap

Custom Bootstrappers

Last updated August 2026Applies to BootStrap v1.0.0+

Overview

The "bootstrapper" is the small window you see while Roblox is being downloaded, updated or prepared — progress bar, status text, maybe a logo. In most launchers that window is fixed. In BootStrap it's a canvas: describe what you want in an XML file and BootStrap renders it as your launcher's face while it works.

People use this to make minimal launchers, retro-styled ones, or branded windows for communities. If you can picture a progress dialog, you can build it.

The XML schema

A bootstrapper file is plain XML rooted at a single <Bootstrapper> element. Inside, you compose the window out of a handful of element types:

ElementPurposeCommon attributes
<Window>The dialog itself — size, titlebar, corner roundingTitle, Width, Height, CornerRadius
<Panel>A container that positions its childrenBackground, Align, Margin
<Image>A logo or decorative graphicSource, Width, Height, Align
<Text>A label; supports live status textContent, FontSize, Color, Align
<ProgressBar>The download/update progress indicatorWidth, Height, Foreground, Background

Align accepts values like TopCenter, BottomCenter and Center; Margin uses CSS-style offsets to fine-tune placement. Elements nest inside each other to build up layouts.

The blank template

The blank template gives you an empty window shell — everything from background colour to element placement is yours to define:

blank.xml 
<?xml version="1.0" encoding="utf-8"?>
<Bootstrapper>
</Bootstrapper>

Use blank when you want full creative control, or as a starting point after studying how the simple template is put together.

The simple template

The simple template is a complete, working example: centred logo, live status text and a progress bar on a dark panel. Use it as-is, tweak values, or copy pieces of it into your own design:

simple.xml 
<?xml version="1.0" encoding="utf-8"?>
<Bootstrapper>
  <Window Title="Roblox" Width="420" Height="190" CornerRadius="8">
    <Panel Background="#1B1D24">
      <Image Source="logo.png" Width="64" Height="64"
             Align="TopCenter" Margin="0,24,0,0"/>
      <Text Content="Getting Roblox ready…"
             Align="BottomCenter" Margin="0,0,52,0" FontSize="13"/>
      <ProgressBar Width="320" Height="4"
             Align="BottomCenter" Margin="0,0,32,0"/>
    </Panel>
  </Window>
</Bootstrapper>

The exact attribute set grows over time — treat this sample as illustrative of the schema's shape rather than an exhaustive reference.

Applying your style

  1. Save your XML anywhere you like (a dedicated folder for bootstrapper experiments is wise).
  2. Open Settings → Appearance → Custom bootstrapper style.
  3. Select your file. The next time Roblox launches, your window appears instead of the default.

Switching back to the built-in style takes one click in the same place, so experimenting is risk-free.

Sharing examples

Made something cool?

If you publish a custom bootstrapper for others to use — on forums, in videos, anywhere — link back to this wiki page (wiki/custom-bootstrappers/) so people know exactly where the file goes and how to install it.