# Haxe: one language, many targets, and what that costs you > Haxe compiles a single strictly typed codebase to JavaScript, C++, JVM, PHP, Python, Lua, HashLink, Neko, Flash and its own interpreter. The compiler is the interesting part, and so are the constraints. **HaxeFoundation/haxe** — Haxe - The Cross-Platform Toolkit - Repository: https://github.com/HaxeFoundation/haxe - Website: https://haxe.org - Stars: 6,939 · Forks: 716 - Language: Haxe - License: NOASSERTION - Published: 2026-09-22 · Updated: 2026-09-22 · Language: en - Canonical page: https://hysenlabs.com/projects/haxefoundation-haxe ## The problem Haxe solves, and the developer it is aimed at Most cross-platform stories are really porting stories. You write the thing once, then rewrite the parts that touch the platform, then maintain the rewrites separately. Haxe takes the opposite position: the source is written once in a strictly typed, high-level language, and the Haxe cross-compiler emits code for the target you select. The README lists JavaScript, C++, JVM, Lua, PHP 7, Python 3, HashLink, NekoVM, Flash (SWF bytecode) and the project's own interpreter as outputs. The audience follows from that list. It is for people whose deployment surface is genuinely plural: a browser build and a native build from one repository, a server component in PHP or Python alongside a client in JavaScript, or a game that ships to several runtimes. The toolkit is described as three pieces that ship together: the Haxe programming language, the Haxe cross-compiler, and the Haxe standard library, which the README calls a complete, cross-platform library of common functionality. If you only ever deploy to one runtime, that third piece is the part you pay for and never use. ## How the compiler, the standard library and haxelib fit together The architecture visible in the repository is a compiler written in OCaml, driving a standard library written in Haxe. The top level holds src/ for the compiler sources, std/ for the standard library, libs/ and plugins/, plus dune and dune-project, which is the OCaml build system. The Makefile confirms the split: it builds src/haxe.exe through dune with a release profile, and the default target is 'all: haxe tools', so building everything produces both the compiler and the tooling rather than the compiler alone. Compilation is target-directed. You name an output target and the compiler produces code for it, drawing on the standard library for the abstractions that exist across platforms. The README's version compatibility table is the part worth reading before you plan anything, because it maps Haxe versions to the runtime versions each one supports. Haxe 4.0.0 is listed against Neko 2.3.0, HashLink 1.11 and PHP 7.0+, while 3.4.0 is the row that carries PHP 5.4+ and 7.0+ with the -D php7 define, and 3.3.0 is the row that carries Lua 5.1 through 5.3 plus LuaJIT 2.0 and 2.1. The table stops at 4.0.0 even though the repository has since released 4.3.6, 4.3.7 and a 5.0.0-preview.1, so for anything newer than 4.0.0 you are reading release notes rather than that table. Haxelib is the package manager, documented separately at lib.haxe.org rather than in the README. That separation matters in practice: the compiler is one install, and every third-party library you pull in is a second thing with its own compatibility story. ## Installing Haxe and compiling a first target The README points at haxe.org/download for the latest stable release and lists pre-built binaries per platform: a Windows installer and a Windows zip, an OSX installer pkg and an OSX tar.gz, Linux software packages, and 32-bit and 64-bit Linux tarballs. There is also build.haxe.org for automated development builds. Download the archive for your platform and put the extracted directory on your PATH, or run the installer. Once the compiler is on your PATH, the first useful check is the version, because the version determines which runtime versions you can target according to the compatibility table. ## Building the compiler from source, and the OCaml dependency that comes with it Building from source is documented in extra/BUILDING.md, which the README links rather than reproducing. The repository layout tells you what that involves: dune and dune-project at the top level mean the OCaml build system is a prerequisite, not an optional extra. The Makefile's own comments say to use 'make' to build all and 'make haxe' to build only the compiler without the libraries, and note that installing ocamlopt.opt and switching OCAMLOPT to ocamlopt.opt is how you get a quicker build. Windows users are directed to Makefile.win, with MSVC=1 as a variant when building with OCaml and MSVC. The default install prefix in the Makefile is /usr/local, split into bin, lib/haxe and share/haxe/std. That last path is the one to remember: the standard library is installed as files, so a mismatched or missing std directory is a failure mode you can hit independently of the compiler binary itself. The Makefile also supports STATICLINK and ADD_REVISION switches, and derives package names from the git commit date and short SHA, which means source builds carry build metadata that pre-built releases do not. ## Where Haxe is the wrong tool The honest limitation is that cross-compilation does not make platform differences disappear. The version compatibility table is the clearest evidence: Haxe 3.3.0 supports Lua 5.1, 5.2, 5.3, LuaJIT 2.0 and 2.1, while the PHP row for 3.4.0 requires a -D php7 define to reach PHP 7.0+ and otherwise sits at 5.4+. Those are runtime constraints you inherit, not abstractions you escape. Targeting PHP 7 on a Haxe version that predates the define, or LuaJIT on a version outside the listed range, is a real dead end. Second, the compiler is written in OCaml. That is fine if you only consume pre-built binaries, and it becomes a hard dependency the moment you build from source or want to patch the compiler. It narrows the set of people on your team who can debug a compiler-level problem. Third, the README's compatibility table has not been extended past Haxe 4.0.0. Anyone running 4.3.x or the 5.0.0-preview.1 build is working from release notes and the manual rather than that table. If your planning document cites the README table as the authority for a current release, it is out of date. Finally, this is not a good fit for a single-target project. The standard library and the target abstraction exist to serve multiple outputs. On one output they are weight you carry without return. ## Haxe against a general-purpose language with a transpiler bolted on The obvious alternative is a mainstream language plus a transpiler, for example TypeScript compiled to JavaScript and separately to native through a third-party toolchain. The difference in approach is where the abstraction lives. In that arrangement the language is defined by one runtime and other outputs are downstream translations, so the type system and standard library are shaped by the primary target. In Haxe the compiler is the centre: the README describes the toolkit as a language, a cross-compiler and a cross-platform standard library, and the target list is a first-class part of the product rather than an add-on. That shows up in the version matrix. Because targets are peers, Haxe has to publish which runtime versions each Haxe release supports, which is exactly what the compatibility table does. A transpiler bolted onto a single-runtime language rarely needs a table like that, because it has one runtime that matters. The trade is that Haxe's standard library must stay within what every listed target can express, and that is a narrower surface than a library written for one platform. ## Maintenance, releases and what the licences let you redistribute The repository is not archived, and the last push was on 2026-09-18. That is recent activity on the development branch. Release cadence visible in the repository is uneven: 4.3.6 on 2024-08-07, 4.3.7 on 2025-05-09, and 5.0.0-preview.1 on 2025-07-04. A preview release is not a stable one, so pinning to 5.0.0-preview.1 in production means accepting preview semantics. Upgrade cost is dominated by the version matrix rather than by the compiler install. Moving a Haxe version can move the runtime versions you are allowed to target, and moving a runtime can force a Haxe version. Budget for testing on the specific runtime version you deploy, not just for compiling successfully. On licensing, the README states that the project has several licences covering different parts. The compiler is GNU General Public License version 2 or any later version. The standard library is MIT. The Neko virtual machine is MIT, and its bundled runtime libraries (ndll) and tools are under open source licences described in the Neko repository. The repository's LICENSE field is reported as NOASSERTION, so if you redistribute anything, read ./LICENSE and the foundation's open source page rather than assuming a single licence covers the whole toolkit. That is a description of what the README says, not legal advice. ## Conclusion Adopt Haxe when you have one codebase that genuinely has to run on several of the targets the compiler lists, and when you are prepared to own a small toolchain that includes the Haxe compiler, haxelib and a runtime such as HashLink or Neko. Do not adopt it if you only ever ship to one runtime: a native toolchain for that runtime will have fewer moving parts and a larger hiring pool. Before committing, verify three things yourself: that the exact target you need is listed in the README's target list, that your build machine can produce the compiler through extra/BUILDING.md, and which licence applies to the parts you redistribute, because the compiler is GPL-2.0-or-later while the standard library is MIT and the two are not interchangeable. ## FAQ ### Is Haxe a programming language? Yes. The README describes the Haxe toolkit as including the Haxe programming language, a modern, high-level, strictly-typed programming language, alongside the cross-compiler and the standard library. ### What is Haxe? It is an open source toolkit for building cross-platform tools and applications that target many mainstream platforms. It consists of the Haxe language, the Haxe cross-compiler and the Haxe standard library. ### Who uses Haxe? The README does not describe its user base. It lists the targets the compiler supports, including JavaScript, C++, JVM, Lua, PHP 7, Python 3, HashLink, NekoVM, Flash and the project's own interpreter, and points to the community forum, Stack Overflow, Gitter and Discord for help. ### Is Haxe still used? The repository is not archived and the last push was on 2026-09-18, with 4.3.6, 4.3.7 and 5.0.0-preview.1 listed as recent releases. The README does not contain usage figures, so popularity cannot be confirmed from it. ## Sources - [HaxeFoundation/haxe on GitHub](https://github.com/HaxeFoundation/haxe) - [Issues](https://github.com/HaxeFoundation/haxe/issues) - [Project website](https://haxe.org) - [README](https://github.com/HaxeFoundation/haxe/blob/development/README.md) - [Releases](https://github.com/HaxeFoundation/haxe/releases) --- Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/haxefoundation-haxe