js_of_ocaml vs Transcrypt
js_of_ocaml
ocsigen.orgTranscrypt
transcrypt.orgSide by side
| Figure | js_of_ocaml | Transcrypt |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | — | Yes |
| macOS | — | Yes |
| Linux | Yes | Yes |
| API | Yes | — |
| Self-hosted | — | Yes |
| Plans published | 1 | 1 |
| Spec score · Code Transpilers | 8.4 (#5) | 8.0 (#9) |
| Installation | The compiler and related packages are installable through opam, the OCaml package manager. | The site recommends installing Transcrypt with pip as a Python package. |
| JavaScript interoperability | The library provides a typed interface for bridging OCaml and JavaScript values, with PPX syntax for JavaScript properties, methods, constructors, and objects. | Transcrypt applications can use JavaScript libraries and browser DOM functions. |
| Purpose | js_of_ocaml compiles OCaml bytecode programs to JavaScript for use in browsers and Node.js. | Transcrypt compiles Python source code into JavaScript for browser applications. |
| Support | The project asks users to report problems or questions through GitHub issues and include version details and a minimal reproducible example when possible. | The FAQ recommends Stack Overflow for help and says commercial support is available on demand. |
Plans
In their own words
js_of_ocaml
js_of_ocaml compiles OCaml bytecode programs into JavaScript for browsers and Node.js. It works with an existing OCaml installation and does not require libraries to be recompiled. Installation is available through opam, while Dune supports separate compilation in development and whole-program compilation in release builds. Whole-program compilation performs global dead-code elimination and cross-module optimization. The library provides a typed bridge between OCaml and JavaScript, including PPX syntax for properties, methods, constructors and objects. Browser bindings cover the DOM, Fetch, WebSockets, WebGL, workers and typed arrays. Optional packages add Lwt support, TyXML, JSON derivation and an OCaml toplevel in the browser. Documented targets include Node.js 18 or later, QuickJS-NG and modern ECMAScript 2020 browsers, including Chrome 80+, Firefox 74+, Safari 13.4+ and Edge 80+. Requirements include OCaml 4.13–5.5, Dune 3.20 or later and Menhir. The project is free and open source.
Transcrypt
Transcrypt compiles Python source code into JavaScript for browser applications. It converts a substantial subset of Python into JavaScript 6, with optional minification, and supports features including multiple inheritance, async/await, comprehensions, and modules. Developers can call JavaScript functions from Python and use browser DOM functions and JavaScript libraries. The distribution includes optional static type validation and consistency checks, plus multilevel source maps for tracing generated JavaScript back to the original Python. Transcrypt can also compile Python server code for Node.js and use Node libraries with require(). The project recommends installing it as a Python package with pip and documents testing on Windows, Linux, and OSX. Its focus is browser development and JavaScript libraries rather than desktop Python libraries. Because code is precompiled, Python exec and eval are unsupported, although JavaScript eval is supported. C and C++ libraries are not directly supported for browser use without special measures such as compiling them to asm.js. Transcrypt is free and open source under Apache 2.0.