termcolor

termcolor is a widely used Rust library for writing colored text to a terminal, using ANSI escape sequences on Unix and the Windows console API on Windows. Its WriteColor trait extends std::io::Write with color-setting methods, and its Buffer and BufferWriter types let multi-threaded programs build colored output in parallel without interleaving.

What You Get

• A WriteColor trait that adds set_color and reset to any io::Write
• StandardStream and StandardStreamLock analogous to std stdout and stderr
• In-memory Buffer and BufferWriter for parallel, non-interleaved output
• Ansi and NoColor writers for explicit control over color emission

Common Use Cases

• Adding colored, cross-platform output to a command-line tool
• Rendering colored results from multiple threads without interleaving
• Respecting user color preferences via ColorChoice detection

Under The Hood

Architecture

The entire library lives in a single lib.rs that defines the WriteColor trait and its implementors: StandardStream and Ansi emit escape sequences, NoColor strips them, and on Windows the writers call into winapi-util to drive the console. Buffer holds colored output in memory, and BufferWriter serializes printing so concurrent buffers never interleave.

Tech Stack

Rust (edition 2018) with a single conditional dependency, winapi-util, used only on Windows targets. No runtime dependencies exist on Unix, keeping the crate extremely lightweight.

Code Quality

Authored by BurntSushi (of ripgrep and regex fame), the crate is mature, meticulously documented, and dual-licensed under Unlicense or MIT. Its tiny dependency footprint, stable API across 1.x, and heavy real-world use (hundreds of millions of downloads) make it a reference-quality utility.

API Design

The API is deliberately minimal: create a StandardStream with a ColorChoice, call set_color with a ColorSpec, and write as usual. The WriteColor trait composes cleanly with existing io::Write code, so adding color to an existing program requires almost no restructuring.