T3X/0 is a small, portable, procedural, block‑structured, recursive, almost typeless language and the newest member of the T3X family. Its compiler is freely available under a 0BSD license or public domain. The syntax resembles Pascal, while the semantics echo BCPL. A cheat sheet PDF is provided.

The package ships with two editors—one VI‑compatible and one Word Star‑compatible—each with built‑in compiler support. Compiling a program is as simple as pressing three keys; errors cause the editor to jump to the offending line. This workflow works even on legacy systems like CP/M 2.2.

T3X/0 serves as a teaching language in books such as "Write Your Own Retro Compiler" and "Write Your Own Programs" and is formally defined in "The T3X Programming Language – Formal Definition." A minimal "Hello, World!" program demonstrates its syntax.

The language runs on Unix (386, x86_64, ARMv6, ARMv7), FreeBSD‑386, macOS, DOS 2.0+, and CP/M 2.2. It self‑hosts on all supported platforms and can cross‑compile to any 16‑bit target. The current compiler source is ~350KB, includes the Tcode Virtual Machine, editors, libraries, example programs, and pre‑compiled binaries for DOS, CP/M, and the Agon Light 2 disk image.