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Status: Alpha — Rezi is under active development and changing rapidly. APIs and behavior may change between releases, and Rezi is not yet recommended for production workloads.

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What is Rezi?

Rezi is a high-performance terminal UI framework for TypeScript. You write declarative widget trees — a native C engine handles layout diffing and rendering. 56 built-in widgets cover everything from layout primitives and form controls to data tables, virtual lists, navigation, overlays, a code editor, diff viewer, and advanced visualization widgets. Sub-character resolution graphics via braille (2×4), sextant (2×3), quadrant (2×2), and halfblock (1×2) blitters let you draw lines, shapes, and gradients within a single terminal cell grid. Inline images work via Kitty, Sixel, or iTerm2 graphics protocols with automatic blitter fallback. Binary drawlists + native C framebuffer diffing move the hot rendering path out of JavaScript — the framework stays ergonomic at the top and fast on real workloads.

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Quick Example

import { ui } from "@rezi-ui/core";
import { createNodeApp } from "@rezi-ui/node";

const app = createNodeApp<{ count: number }>({
  initialState: { count: 0 },
});

app.view((s) =>
  ui.page({
    p: 1,
    gap: 1,
    header: ui.header({ title: "Counter", subtitle: "Beautiful defaults" }),
    body: ui.panel("Count", [
      ui.row({ gap: 1, items: "center" }, [
        ui.text(String(s.count), { variant: "heading" }),
        ui.spacer({ flex: 1 }),
        ui.button("inc", "+1", {
          intent: "primary",
          onPress: () => app.update((prev) => ({ count: prev.count + 1 })),
        }),
      ]),
    ]),
  }),
);

app.keys({ q: () => app.stop() });
await app.start();

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Key Features

Native Performance

Binary drawlists + C framebuffer diffing — 10-200x faster than React-based TUI frameworks in most scenarios.

56 Built-in Widgets

Complete widget catalog from primitives to advanced components: tables, virtual lists, code editor, diff viewer, charts, canvas, and more.

Sub-Character Graphics

Canvas drawing at 2×4 braille resolution. Charts, heatmaps, sparklines, and inline images with automatic terminal protocol detection.

JSX Without React

Optional @rezi-ui/jsx maps JSX directly to Rezi VNodes with zero React runtime overhead.

Deterministic Rendering

Same state + same events = same frames. Versioned binary protocol and pinned Unicode tables ensure reproducible output.

Developer Experience

Hot state-preserving reload, 6 built-in themes, declarative animation APIs, automatic focus management, and syntax tokenizers.

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How It Works

Rezi separates authoring from rendering: 
Application Code (TypeScript)
        │
        ▼
@rezi-ui/core      Layout, widgets, protocol builders
        │ ZRDL drawlist
        ▼
@rezi-ui/node      Node.js/Bun backend
        │
        ▼
@rezi-ui/native    N-API binding
        │
        ▼
Zireael (C engine) Framebuffer diff, ANSI emission
        │
        ▼
Terminal
Data flows down as binary drawlists (ZRDL). Input events flow up as event batches (ZREV). Both are versioned binary formats validated at the boundary.

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Who is Rezi for?

Rezi is built for:
  • Real-time dashboards — stable live telemetry displays
  • Developer tooling — CLI tools with rich interactive UIs
  • Control planes — operations consoles for infrastructure management
  • Log viewers — high-performance text processing and display
  • Terminal-first applications — teams who want TypeScript ergonomics without sacrificing performance

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Performance

Rezi is benchmarked against Ink, OpenTUI (React and Core drivers), Bubble Tea, terminal-kit, blessed, and Ratatui across 22 scenarios covering primitive workloads, terminal-level rendering, and full-app UI composition. vs Ink — 10-200x faster across all measured scenarios
vs OpenTUI (React) — ~10x faster geomean across 21 scenarios
vs OpenTUI (Core) — ~2.6x faster geomean, faster in 19/21 scenarios
vs Bubble Tea — faster in 20/21 scenarios See BENCHMARKS.md for full methodology, caveats, and reproduction steps.

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Next Steps

Installation

Install Rezi packages and set up your environment

Quickstart

Build your first Rezi app in under 5 minutes

JSX Support

Learn how to use JSX with Rezi (no React runtime)

Examples

Explore templates and example applications

Build docs developers (and LLMs) love

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