Overview

jsii allows code in any language to naturally interact with JavaScript classes. It is the technology that enables the AWS Cloud Development Kit to deliver polyglot libraries from a single codebase!

A class library written in TypeScript can be used in projects authored in TypeScript or Javascript (as usual), but also in Python, Java, C# (and other languages from the .NET family), …

Documentation

Head over to our documentation website!

The jsii toolchain is spread out on multiple repositories:

• aws/jsii-compiler is where the jsii compiler is maintained (except releases in the 1.x line)
• aws/jsii-rosetta is where the jsii-rosetta sample code transliteration tool is maintained (except releases in the 1.x line)
• aws/jsii is where the rest of the toolchain is maintained, including:
  • @jsii/spec, the package that defines the .jsii assembly specification
  • jsii-config, an interactive tool to help configure your jsii package
  • jsii-pacmak, the bindings generator for jsii packages
  • jsii-reflect, a higher-level way to process .jsii assemblies
  • The jsii runtime libraries for the supported jsii target languages
  • 1.x release lines of jsii and jsii-rosetta

Blog Posts

Here’s a collection of blog posts (in chronological order) related to jsii:

• 2020-01-11: How to Create CDK Constructs, by Matthew Bonig
• 2020-05-27: Generate Python, Java, and .NET software libraries from a TypeScript source, by Hari Pachuveetil
• 2020-12-23: How the jsii open source framework meets developers where they are , by Romain Marcadier

If you wrote blog posts about jsii and would like to have them referenced here, do not hesitate to file a pull request to add the links here!

:gear: Maintenance & Support

The applicable Maintenance & Support policy can be reviewed in SUPPORT.md.

The current status of jsii compiler releases is:

Release	Status	EOS	Comment
5.9.x	Current	TBD
5.8.x	Unsupported	2026-02-15

🔇 Silencing Warnings

The --silence-warnings option allows you to suppress specific warnings from the compiler output. Silenced warnings are still emitted internally (e.g. they are still part of the assembly), but are not printed to the console. When --fail-on-warnings (--Werr) is set, silenced warnings are not treated as errors.

Warnings can be identified by JSII code, number, or diagnostic name:

# By full JSII code
jsii --silence-warnings JSII5018

# By number only
jsii --silence-warnings 5018

# By specific diagnostic name (the part after the slash)
jsii --silence-warnings reserved-word

# By full diagnostic name
jsii --silence-warnings language-compatibility/reserved-word

# By category (silences ALL warnings in that category)
jsii --silence-warnings language-compatibility

# Multiple warnings
jsii --silence-warnings reserved-word JSII5019

Inline Suppression

Individual warnings can be suppressed directly in source code using the @jsii suppress directive. This is useful when you want --fail-on-warnings enabled globally but need to allow specific instances of a warning.

Each directive accepts a single warning identifier using the same formats as --silence-warnings. An optional text after the identifier is treated as an explanation comment. Use multiple directives to suppress multiple warnings:

export class MyClass {
  /**
   * @jsii suppress JSII5019 this name is intentional
   * @jsii suppress reserved-word
   */
  public myClass(): void { }
}

The suppression applies to the annotated declaration and all of its members. For example, a @jsii suppress directive on a class will suppress matching warnings on all methods and properties within that class.

Only warnings that reference a source code location can be suppressed inline. Warnings not tied to a specific node (e.g. JSII0003 for a missing README) are not affected.

:balance_scale: License

jsii is distributed under the Apache License, Version 2.0.

See LICENSE and NOTICE for more information.

:gear: Contributing

See CONTRIBUTING.

Contributors ✨

Thanks goes to these wonderful people (emoji key):

Aatman 💻	Aaron Costley 🐛 💻 🤔 👀	Abdallah Hodieb 🐛	Adam Ruka 🐛 💻 🚧 👀	Adrian Dimech 💻	Adrian Hesketh 💻	Alex Pulver 🐛
Amir Szekely 💻	Andi Pabst 🐛	Andrew Wason 🐛 💻	André Fontenele 💻	Andy Slezak 💻	Ansgar Mertens 🚧 💻 🐛	Anshul Guleria 🤔
Anurag Roy 💻	Ari Palo 🤔	Armaan Tobaccowalla 🐛	Bartłomiej Jurek 🐛	Ben Bridts 📖	Ben Chaimberg 📖	Ben Farr 📖
Ben Walters 🤔	Benjamin Macher 📖	Benjamin Maizels 💻 👀	Bervianto Leo Pratama 💻	Bill Cauchois 🤔	Bradley Sherman 💻	Brecht Verhoeve 🤔
Breland Miley 💻	Bryan Moffatt 💻	CaerusKaru 💻 🚧	Calvin Combs 💻 👀	Camilo Bermúdez 🐛	Campion Fellin 💻	Carter Van Deuren 🐛
Chris Garvis 📖	Christian Moore 🐛	Christophe Vico 🐛	Christopher Currie 💻 🤔	Christopher Rybicki 📖 🐛 💻	Colin Francis 💻	CommanderRoot 💻
Cory Hall 🐛	Cristian Măgherușan-Stanciu 🐛	CyrusNajmabadi 🐛 🤔	Damian Silbergleith 💻 🐛	Daniel Dinu 🐛 💻	Daniel Schmidt 🐛 💻	Daniel Schroeder 🐛 💻 📖 🤔 🚧
Dave Slotnick 🐛	David Bell 💻	Donald Stufft 🐛 💻 🤔 👀	Dongie Agnir 💻 👀	Eduardo Rabelo 📖	Eduardo Sena S. Rosa 🐛	Elad Ben-Israel 🐛 💻 🤔 🚧 👀 📢
Eli Polonsky 🐛 💻 🤔 🚧 👀	Eric Carboni 💻	Eric Z. Beard 📆	Erik Karlsson 🐛	Eugene Kozlov 💻	Fabio Gentile 🐛	Florian Eitel 🤔
Glib Shpychka 🐛	Graham Lea 🤔 👀	Greg Lucas 💻	Hamza Assyad 🐛 💻 🤔 👀	Hari Pachuveetil 📝 📖	Hirotaka Tagawa / wafuwafu13 💻	Hogan Bobertz 💻
Hsing-Hui Hsu 💻 📖 🤔 👀	Huy Phan (Harry) 💻	Ikko Ashimine 📖	James 🐛 💻	James Kelley 🐛	James Mead 💻	James Siri 💻 🚧
Jason Del Ponte 🤔 👀	Jason Fulghum 🤔 📆 👀	Jeff Malins 💻	Jerry Kindall 📖 🤔	Jimmy Gaussen 🤔	Johannes Weber 📖	John Pantzlaff 💻
Jon Day 💻	Jon Steinich 🐛 🤔 💻	Joseph Lawson 👀	Joseph Martin 🐛	Junix 🐛	Justin Frahm 🐛	Justin Taylor 🐛
Kaizen Conroy 💻	Kaushik Borra 🐛	Kayo 💻	Kendra Neil 💻	Knut O. Hellan 🐛	Kyle Thomson 💻 👀	Leandro Padua 🐛
Liang Zhou 🐛 💻	Madeline Kusters 💻 🐛	Maja S Bratseth 🐛	Marcos Diez 🐛	Mark Nielsen 💻	Matthew Bonig 🐛 📝	Matthew Pirocchi 💻 🤔 👀
Meng Xin Zhu 🐛	Michael Neil 🚧	Mike Lane 🐛	Mitch Garnaat 🐛 💻 🤔 👀	Mitchell Valine 🐛 💻 🤔 🚧 👀	Mohamad Soufan 📖	Mohamed Elasmar 💻
Momo Kornher 💻	Mykola Mogylenko 🐛	Naumel 👀	Neta Nir 💻 🤔 🚧 👀	Nick Lynch 🐛 💻 🚧 👀	Niranjan Jayakar 🐛 💻 🤔 🚧 👀	Noah Litov 💻 🚧 👀
Otavio Macedo 💻 🐛	PIDZ - Bart 🤔	Pahud Hsieh 💻	Peter Woodworth 🚧	Petr Kacer 🐛	Petra Barus 💻	Philip Cali 🤔
Quentin Loos 🤔	Raphael 🐛	Richard H Boyd 🐛	Rico Huijbers 🐛 💻 🤔 🚧 👀	Romain Marcadier 🐛 💻 🎨 🤔 🚧 👀 📝	Ryan Parker 💻	SADIK KUZU 👀
SK 🤔	Sam Fink 💻 👀	Sam Goodwin 👀	Sebastian Korfmann 🐛 💻 🤔	Sepehr Laal 🐛	Shailja Khurana 💻	Shane Witbeck 🤔
Shiv Lakshminarayan 💻 🚧 👀	Somaya 💻 🤔 🚧 👀	Stephen Kuenzli 📖	Takahiro Sugiura 📖	The Gitter Badger 💻 🚧	Thomas Matecki 💻	Thomas Poignant 🐛
Thomas Steinbach 🐛	Thorsten Hoeger 💻	Tim Wagner 🐛 🤔	Timothy Jones 💻	Tobias Lidskog 💻	Tom Bonner 🐛	Tom Keller 💻
Ty Coghlan 🐛	Tyler van Hensbergen 🤔	Vinayak Kukreja 💻	Vlad Hrybok 🐛	Vladimir Shchur 🐛	Will Bender 💻	Yan Zhulanow 💻
Yathi 💻	Yigong Liu 🐛 🤔	Zach Bienenfeld 🐛	ajnarang 🤔	andyan 💻	aniljava 💻	arnogeurts-sqills 🐛 💻
cn-cit 🐛	deccy-mcc 🐛	dependabot-preview[bot] 🐛 🚧	dependabot[bot] 🚧	dheffx 🐛	gregswdl 🐛	guyroberts21 📖
mattBrzezinski 📖	mergify 🚧	mergify[bot] 🚧	mikewrighton 💻	nathannaveen 🚧	paulhcsun 💻	seiyashima42 🐛 💻 📖
sullis 💻	vaneek 🐛	wendysophie 🐛	ysuzuki19 💻

This project follows the all-contributors specification. Contributions of any kind welcome!