OpenTail.TUI is a reactive, Elm-architecture terminal UI framework for .NET — with real mouse support, true 24-bit color, and clickable links, running entirely inside a plain console window.
0 at runtimeMost .NET console libraries make text look nice. OpenTail.TUI builds interactive apps — click a row to select it, drag a slider, click a hyperlink and watch your browser actually open. All of it inside what still looks, at a glance, like a plain console window.
Every interactive widget follows the same contract: Render draws it, HitTest/HandleMouse tells you what a click landed on — computed from the exact same math, so a click always agrees with what's on screen. Click a table row, drag a slider to a value, click a checkbox, open a dropdown.
Init, Update, and View are pure functions over plain C# records. Feed messages into Update in a unit test and assert on the model — no real terminal required.
A double-buffered CellBuffer diffs against the last painted frame and writes only what changed. Live timers, spinners, and glowing text run smoothly without a single stray repaint.
Link.TryOpen launches a URL in the browser. Link.TryOpenFolder opens a directory in Explorer/Finder — and refuses anything that isn't an existing directory first, so it can never run a file. SystemNotification.Show pops a real OS notification.
Every widget draws in full RGB, gracefully degrading on older terminals. ImageWidget renders an actual bitmap via the half-block technique, and can decode an uncompressed BMP file directly — no image-decoding package required.
Every OpenTail.TUI screen is the same four-step loop — the same discipline that makes Elm and Bubble Tea apps easy to reason about, brought to .NET.
Plain C# records hold your screen's entire state — no hidden framework fields.
A pure function maps an incoming message (key, click, tick) to the next model.
Paint the model into a CellBuffer. The diff renderer figures out what actually changed.
AOT-compatible, zero-dependency at runtime — publish a single trimmed binary, any OS.
"Can a user click a table row?"Table.HitTest
"Can they click a hyperlink?"Link + MarkdownBlock
"Will it flicker at 30fps?"Double-buffered diffing
"Does it survive SSH and CI?"Pure ANSI, degrades safely
"Is it actually used anywhere?"Interactive dashboards & tools
Tables, forms, overlays, effects, charts, and layout primitives — organized in WIDGETS.md by the problem each one solves, so "I need a centered modal" leads straight to the widget that already does it correctly.
Every widget is a stateless renderer — construct it fresh each frame with whatever data it needs. Cross-frame state (cursor position, scroll offset, selection) lives in a separate plain record your model owns, which is exactly what keeps Update unit-testable without a terminal.
Interactivity isn't bolted on. Widgets that own a click implement it consistently — Render and HitTest/HandleMouse share the same position math, so a click can never land somewhere different from what's drawn.
OpenTail.TUI is a standalone open-source library — not gated behind any paid product. Use it in any .NET project.
Install from NuGet: dotnet add package OpenTail.TUI. The latest published version is 1.0.1.
Short, direct answers — the same standard the rest of the OpenTail family holds itself to.
Different focus. Spectre.Console is excellent at formatting one-shot console output — tables, prompts, progress bars. OpenTail.TUI is built for full interactive apps: an Elm-style Update/View loop, live-updating dashboards, and real mouse input, including clicking a table row or a hyperlink.
No special terminal, but it does need one that reports SGR mouse events — true of essentially every terminal shipped in the last decade (Windows Terminal, iTerm2, GNOME Terminal, kitty, WezTerm, ...). Where mouse input isn't available, input falls back to keyboard-only automatically.
Nothing at runtime. The only package reference in the project is MinVer, and that's a build-time-only version stamp — it never ships with your app.
Yes — the project builds with IsAotCompatible set, and the native console interop uses source-generated P/Invoke (LibraryImport), not reflection.
Yes — interactive dev tools, status monitors, and live dashboards use OpenTail.TUI. Check out the built-in Widget Gallery to see the mouse support, the widget catalog, and the rendering all working together.
Rendering works anywhere ANSI does, including over SSH. When input is redirected — piped, or running non-interactively in CI — the input loop detects that and idles safely instead of crashing.