About#

ttkbootstrap is a theming extension for tkinter. It generates modern, flat, Bootstrap-inspired themes on demand and adds a single bootstyle keyword to the widgets you already use — so a standard tkinter app can look current without a complete rewrite.

Beautiful, easy-to-use styles#

Creating ttk styles by hand is tedious. Between element layouts, state maps, and image assets, a single good-looking submit button can mean adjusting a couple dozen settings. ttkbootstrap takes that pain away: it ships a curated set of light and dark themes with a Bootstrap-inspired palette, so you can spend your time designing your application instead of hand-tuning widget styles.

Style with keywords#

Keep it simple. Set a widget’s look with a keyword instead of a ttk style class. Where plain ttk wants success.Horizontal.TProgressbar, ttkbootstrap wants success — one semantic keyword that carries the same meaning on every widget:

ttk.Button(app, text="Save", bootstyle="success")
ttk.Progressbar(app, bootstyle="success")
ttk.Entry(app, bootstyle="success")

Anyone who has used Bootstrap for the web will recognize the idea: a small set of semantic classes — primary, success, danger — that give you a consistent, professional API for building quickly. I took the same approach here, pre-defining styles for nearly every ttk widget and letting you reach them with plain keywords.

In 2.0 that keyword language became a proper grammar. A bootstyle is a fixed set of slots — a color, an optional modifier, a widget type, an optional orientation — written with spaces: "primary outline", "success round toggle", "info striped". The vocabulary is closed, so a typo now fails loudly instead of silently doing nothing. See the bootstyle grammar for the full language.

Build only what you use#

If you are not using a style, it should not be taking up memory in your app. Nothing bloats an application like a pile of assets it may never touch.

So ttkbootstrap builds ttk styles and themes on demand. A style that is never used is never created. To put that in perspective: in the old image-based approach (ttkbootstrap 0.5), a single scale widget meant loading 288 images to cover every possible theme and color combination — that is simply how ttk styles were traditionally handled. By 1.0, the on-demand engine cut that to the three or four images the widget actually needs for its hover and pressed states. Only what you use gets built.

2.0 rebuilt that engine again, this time for speed and memory over the whole life of the app. Identical assets are now rendered exactly once and shared; switching themes repaints only the widgets currently on screen — styles rebuild lazily, as they are needed, rather than all at once — and the image references that used to accumulate across theme switches are gone. Theme switching is fast, and it stays fast.

A styling extension, not a widget library#

ttkbootstrap is deliberately a styling layer for vanilla tkinter, not a new UI framework. The widgets are tkinter’s widgets; ttkbootstrap themes them and adds a handful of conveniences. Everything you already know about tkinter — the geometry managers, variables, events, the widget tree — still applies, and the documentation teaches it in that dialect rather than sending you elsewhere.

That focus is a design choice. ttkbootstrap stays small, dependency-light (only Pillow), and true to the library it extends. If you want the other thing — a full component framework with its own widgets, reactive state, and app packaging — that’s a separate project called bootstack, built on Tk by the same author.

What 2.0 brings#

2.0 is a cleanup and consolidation release — not a grab-bag of new features, but a sharper, more consistent version of the same idea:

a normalized, keyword-first API, with the old import-time monkey-patch retired in favor of plain widget classes;
the single canonical bootstyle grammar described above;
a semantic-anchor theme model with a curated catalog of light and dark themes, surface elevation, and addressable color ramps;
crisp, theme-following icons rendered from a built-in icon font (icon=) — no image files to manage;
a public toolkit that makes your own custom styles and themes straightforward;
and a top-to-bottom documentation rewrite.

The through-line is the same as day one: make a standard tkinter app look good with as little ceremony as possible.

Support#

ttkbootstrap is proudly developed with the support of the PyCharm IDE, generously provided by JetBrains.

ttkbootstrap is released under the MIT License. Release notes for every version are published on the GitHub releases page.