Build rich terminal UIs from Java. jatatui is a faithful port of ratatui — same widgets, same buffer model, same Crossterm backend — translated to idiomatic modern Java (records, sealed interfaces, switch expressions). Plus an optional React-style component layer on top.

The non-React stack (crossterm + jatatui-core + jatatui-widgets + jatatui-crossterm) is a complete library on its own. The React layer is opt-in.

Coordinates: com.olvind.jatatui.

Maven:

<dependency>
  <groupId>com.olvind.jatatui</groupId>
  <artifactId>jatatui-core</artifactId>
  <version>0.30.0</version>
</dependency>
<dependency>
  <groupId>com.olvind.jatatui</groupId>
  <artifactId>jatatui-widgets</artifactId>
  <version>0.30.0</version>
</dependency>
<dependency>
  <groupId>com.olvind.jatatui</groupId>
  <artifactId>jatatui-crossterm</artifactId>
  <version>0.30.0</version>
</dependency>

Gradle:

implementation("com.olvind.jatatui:jatatui-core:0.30.0")
implementation("com.olvind.jatatui:jatatui-widgets:0.30.0")
implementation("com.olvind.jatatui:jatatui-crossterm:0.30.0")

The version tracks the upstream ratatui release jatatui ports from. JVM target is Java 21.

import jatatui.core.style.*;
import jatatui.core.text.Line;
import jatatui.core.widgets.Widget;
import jatatui.crossterm.Jatatui;
import jatatui.widgets.Borders;
import jatatui.widgets.block.Block;
import jatatui.widgets.paragraph.Paragraph;

public class Hello {
  public static void main(String[] args) throws java.io.IOException {
    Jatatui.runIo(terminal -> {
      while (true) {
        terminal.draw(frame -> {
          Block block = Block.empty()
              .withTitle(Line.from(" Hello "))
              .withBorders(Borders.ALL)
              .withBorderStyle(Style.empty().withFg(new Color.Yellow()));
          Widget content = Paragraph.of("Press q to quit.")
              .withStyle(Style.empty().withFg(new Color.White()));
          block.render(frame.area(), frame.bufferMut());
          content.render(block.inner(frame.area()), frame.bufferMut());
        });
        // (your event loop here — read keys via the crossterm JNI binding)
      }
    });
  }
}

For something more substantive, see the demos in jatatui-demo/ (porting of the upstream examples/apps/*) and the React-style demos in jatatui-demo-react/.

jatatui-react and jatatui-components add a React-shaped API: components as pure functions, hooks for state, event bubbling, focus management. Same buffer underneath — just different ergonomics.

import static jatatui.react.Components.*;
import static jatatui.components.Components.*;
import jatatui.react.ReactApp;
import tui.crossterm.KeyCode;

public class Counter {
  public static void main(String[] args) throws java.io.IOException {
    ReactApp.run(component(ctx -> {
      var n = ctx.useState(() -> 0);
      ctx.onGlobalKey(new KeyCode.Up(),   () -> n.update(v -> v + 1));
      ctx.onGlobalKey(new KeyCode.Down(), () -> n.update(v -> v - 1));
      return text("count = " + n.get());
    }));
  }
}

What's available: useState, useRef, useEffect, useFocus, useContext, memo, pureComponent; column / row / box / stack layouts; portal for overlays; text / paragraph / button / tabs / forEach; bubbling mouse/key events with stopPropagation; the widget(...) escape hatch wraps any jatatui-widgets widget into the tree.

Higher-level components (jatatui-components): textInput, titledTextInput, modal, dropdown, toastsProvider + useToasts, formProvider + useForm

• useField, router + useRouter, themeProvider + Theme.useTheme, list, table, gauge, lineGauge, barchart, sparkline, scrollbar.

Design notes: jatatui-react/DESIGN.md.

bleep is the build tool. The version is pinned in bleep.yaml ($version: 1.0.0-M9); the bleep launcher picks it up automatically.

cd jatatui
bleep compile
bleep test jatatui-tests
bleep run jatatui-demo -- demo2
bleep run jatatui-demo-react -- counter

For consuming jatatui from other local projects without waiting for a release:

cd jatatui
bleep publish local-ivy --version "0.30.0_$(date +%Y-%m-%d)-SNAPSHOT"

This publishes the six publishable modules (crossterm, jatatui-core, jatatui-widgets, jatatui-crossterm, jatatui-react, jatatui-components) to the local Ivy repo (~/.ivy2/local/). The version is stable for the day (consumers can pin it), and re-publishing the next day produces a fresh identifier — handy for picking up changes without a coordinate dance.

// in another project's build
implementation("com.olvind.jatatui:jatatui-widgets:0.30.0_2026-05-14-SNAPSHOT")

Releases are tagged jatatui-vX.Y.Z and published to Maven Central by the build workflow. Required secrets in the repository: PGP_SECRET, PGP_PASSPHRASE, SONATYPE_USERNAME, SONATYPE_PASSWORD (see bleep's publish setup or sbt-ci-release docs for the GPG / Sonatype workflow — bleep's publish reuses the same env vars).

To cut a release: tag the head commit, push the tag.

git tag jatatui-v0.30.0
git push origin jatatui-v0.30.0

The workflow runs bleep publish sonatype --version 0.30.0 --assert-release, uploads native libraries from all 5 platforms, and creates a GitHub Release.

Port progresses per upstream source file. See PORTING_PLAN.md for the live status board and CLAUDE.md for the porting workflow and translation conventions.

MIT (same as ratatui). See LICENSE.