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Ratatui

Using no_std

Ratatui is no_std-compatible, which allows it to run in embedded and other resource-constrained environments. This means you can run TUIs on a wider range of targets and have widget usable in both desktop and embedded environments.

Using Ratatui without std

Section titled “Using Ratatui without std”
  1. Disable default features so the crate does not pull in std-only dependencies:
ratatui = { version = "0.30", default-features = false }
  1. Choose a backend that works on your platform.

The built-in backends rely on std, so no_std targets need a custom backend that implements ratatui::backend::Backend or a third-party option like mousefood 🧀

  1. When checking a no_std build, compile with a no_std target.

For example, on ESP32:

Terminal window
cargo check --target riscv32imc-unknown-none-elf

Creating no_std widgets

Section titled “Creating no_std widgets”

If you already have a Ratatui widget, you can make it no_std-compatible with a few small changes. Even if you haven’t built for embedded before!

  1. Opt into no_std and add alloc crate:

    lib.rs
    #![no_std]
    extern crate alloc;

  2. Depend on ratatui-core instead of the full ratatui crate to avoid backend dependencies:

    ratatui-core = { version = "0.30", default-features = false }

  3. Swap std types for their core/alloc equivalents, for example core::fmt, alloc::string::String, alloc::vec::Vec, and alloc::boxed::Box.

  4. Keep a std feature (off by default) for conveniences like tests or examples, but write your core widget logic so it also works without it.

  5. Avoid std-only APIs in widget code paths. Examples: use core::time::Duration instead of std::time::Duration, pass in data rather than reading files, and keep logging behind a feature so it can be disabled on targets without I/O.

Here is a minimal no_std widget implementation:

#![no_std]
extern crate alloc;


use alloc::string::String;


use ratatui_core::buffer::Buffer;
use ratatui_core::layout::Rect;
use ratatui_core::text::Line;
use ratatui_core::widgets::Widget;


struct Greeting {
    message: String,
}


impl Widget for &Greeting {
    fn render(self, area: Rect, buf: &mut Buffer) {
        Line::raw(&self.message).render(area, buf);
    }
}