Unmodified Java Swing apps in any browser, fully client side

In plain words

CheerpJ enables unmodified Java Swing applications to run directly in web browsers as fully client-side programs. Developed by Leaning Technologies, it allows developers to deploy existing Java desktop applications to the web without modification. The technology is designed for users who need Java Swing applications accessible online, eliminating the need for server-side processing or installation.

written from the facts on this page · September 2026

From the sources

Click the buttons below to start any demo. Please note that if this is you first CheerpJ demo, there will be an initial download of approximately 15from cheerpjdemos.leaningtech.com

• 
  CheerpJ2024 · cheerpj.com · ▲5

  The complete Java runtime for modern browsers

• CX
  CheerpX – x86 virtualization in browser using WebAssembly – Python Demo2020 · leaningtech.com · ▲26

  Run anything in the browser with Leaning Technologies

• C1
  CheerpJ 1.3 – Compile any Java application to JS/HTML52018 · medium.com · ▲10
• 
  CheerpX – x86 Node.js/python3/Ruby REPL in browser via WebAssembly JIT2021 · repl.leaningtech.com · ▲88

  Linux virtual machine, running in the browser via HTML5/WebAssembly. Networking and graphics supported.

• BU
  Browsercraft – Unmodified Minecraft in the browser2024 · browsercraft.cheerpj.com · ▲6

  CheerpJ: a WebAssembly JVM running unmodified Java in the browser - Minecraft 1.2.5 proof-of-concept demo.

• 
  Tailwind CSS v2.02020 · tailwindcss.com · ▲385

  Rapidly build modern websites without ever leaving your HTML

• 
  SimCity, but with Permits▲914

  A free city-building game in your browser. You are the mayor. You know what the city needs. Now get it past the zoning board, the neighbors, the appeals court and the next election.

  Life & fun · 2d ago · permit.petercai.com

• IV
  I've been paying for a rural Tanzanian's education for 10 years▲778

  Life & fun · 14d ago · tanzaniaeducationproject.org

• 
  Bigwords.page – Turn any screen into a sign. The URL is the app▲728

  Turn a phone, tablet or TV into a sign. Type a message and it fills the screen: welcome signs, timers, Wi-Fi passwords and more. No app, no account, free.

  Life & fun · 15d ago · bigwords.page

• 
  Guitoro, a virtual guitar you strum with your keyboard▲573

  Play a free virtual guitar online with your keyboard or by touch. Slow songs down and see every chord, string and strum. Acoustic, classic, electric and bass.

  Life & fun · 9d ago · guitoro.com

• 
  See *almost* any carriers phone settings▲432

  Carrier settings from iPhone, Pixel and Galaxy firmware, decoded and compared: APNs, VoLTE, 5G and Wi-Fi Calling per carrier, and what each build changed.

  Life & fun · 13d ago · carrierexplode.com

• 
  The whole Solar System and every tracked satellite, live in the browser▲407

  Life & fun · 23d ago · space.bl2.net

• GP
  Get Paid to Build Your Next Side Project▲1,100

  Work · 2017 · demandrush.com

• 
  Monica, an open-source CRM to manage friends and family▲1,097

  Monica helps you remember the people you care about: what is happening in their life, important dates, previous conversations, and when to get back in touch. Private, open source, self-hostable.

  Dev tools · 2017 · monicahq.com

• 
  Feather Icons▲1,017

  Simply beautiful open source icons

  Dev tools · 2017 · feathericons.com

• 
  Roadmap beta▲832

  Plan projects and manage resources with ease.

  Work · 2017 · onroadmap.com

• 
  Runway▲825

  The cash planning tool for startups

  Growth · 2017

• 
  How to Acquire More Users▲806

  The growth guide by DemandCurve.com and Julian Shapiro

  Growth · 2017 · julian.com