Releases, technical deep dives and news about CheerpJ from the Leaning Technologies engineering blog.https://labs.leaningtech.comhttps://labs.leaningtech.com/blog/internships-summer26https://labs.leaningtech.com/blog/internships-summer26Our interns reflect on their 6 month internships at Leaning Technologies Thu, 08 Oct 2026 00:00:00 GMTCheerpJBrowserPodLeaning Technologieshttps://labs.leaningtech.com/blog/cheerpj-4.3https://labs.leaningtech.com/blog/cheerpj-4.3The latest release of our state-of-the-art Java runtime that runs completely in the browser via WebAssembly, is now available! Tue, 21 Apr 2026 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/internshipshttps://labs.leaningtech.com/blog/internshipsOur interns describe their 6 month internships at Leaning Technologies Thu, 06 Nov 2025 00:00:00 GMTCheerpJCheerpXBrowserPodLeaning Technologieshttps://labs.leaningtech.com/blog/cheerpj-hackathonhttps://labs.leaningtech.com/blog/cheerpj-hackathonThe Java in the browser challenge is coming this autumn. Fri, 03 Oct 2025 00:00:00 GMTCheerpJCommunityhttps://labs.leaningtech.com/blog/cheerpj-4.1https://labs.leaningtech.com/blog/cheerpj-4.1The latest release of our state-of-the-art Java runtime that runs completely in the browser via WebAssembly, is now available. Supports up to Java 17. Wed, 28 May 2025 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/cheerpj-4.0https://labs.leaningtech.com/blog/cheerpj-4.0The latest release of our state-of-the-art Java runtime that runs completely in the browser via WebAssembly, is now available! Wed, 23 Apr 2025 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/cheerpj-3.1https://labs.leaningtech.com/blog/cheerpj-3.1Our state-of-the-art JVM/JDK that runs completely in the browser thanks to WebAssembly, is now available! Wed, 05 Feb 2025 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/cheerpj-3.0https://labs.leaningtech.com/blog/cheerpj-3.0CheerpJ 3.0, a state-of-the-art WebAssembly JVM that runs real-world Java applications in the browser, is now available. Thu, 01 Feb 2024 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/dragon-courthttps://labs.leaningtech.com/blog/dragon-courtDragon Court was a free, old-school fantasy, multiplayer browser RPG that came in a Java Applet format but sadly became abandonware. Clarky Lee talks about how he used CheerpJ to bring it back to life. Thu, 14 Dec 2023 00:00:00 GMTCheerpJProjects & Demoshttps://labs.leaningtech.com/blog/cheerpj-3-deep-divehttps://labs.leaningtech.com/blog/cheerpj-3-deep-diveCheerpJ is a WebAssembly-based JVM that runs fully client side in the browser. It supports Java applications, legacy applets and libraries, with no need for compilation, server backends, plugins, or post-processing steps. CheerpJ 3.0 introduces a completely new JIT-based architecture which makes the tool faster, more usable and much more powerful. Thu, 30 Nov 2023 00:00:00 GMTCheerpJTechnicalhttps://labs.leaningtech.com/blog/cheerpj-30rc2https://labs.leaningtech.com/blog/cheerpj-30rc2The CheerpJ 3.0 second release candidate is now available! This release includes many improvements to library mode, Web Worker support, and more. Wed, 29 Nov 2023 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/cheerpj-30rc1https://labs.leaningtech.com/blog/cheerpj-30rc1The first release candidate for CheerpJ 3.0 is now available for testing and feedback. This version features a completely new architecture for CheerpJ, with a full OpenJDK runtime and a new scalable JNI architecture. Wed, 18 Oct 2023 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/join-the-cheerpj-3-0-amahttps://labs.leaningtech.com/blog/join-the-cheerpj-3-0-amaWe hosted a live Ask-Me-Anything (AMA) with CTO and lead dev Alessandro. The main topic was CheerpJ 3.0, but we welcomed any questions across all our products, about WebAssembly, and compilers, or the company in general. We talked about CheerpJ 3.0’s development, its release timeline, and technical details like how 3.0’s architecture differs from 2.0. Tue, 05 Sep 2023 00:00:00 GMTCheerpJCommunityhttps://labs.leaningtech.com/blog/announcing-cheerpj-3https://labs.leaningtech.com/blog/announcing-cheerpj-3For the past year, we have been working on a new architecture for CheerpJ: our implementation of the JVM in HTML5/WebAssembly, designed to run Java applications on the browser. CheerpJ 3.0 will be released in the late summer of 2023, and will be easier to use, faster, and more compatible than ever before. Our live JavaFiddle demo has already been migrated to the current development version. Tue, 09 May 2023 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/a-real-world-use-case-for-wasihttps://labs.leaningtech.com/blog/a-real-world-use-case-for-wasiAt Leaning Technologies we are heavily invested in WebAssembly, and we are actively contributing to push the standard forward. Just a few months ago WebAssembly tail-calls were standardized, and we are currently bringing the branch-hinting proposal to Phase 4. Thu, 06 Apr 2023 00:00:00 GMTCheerpJTechnicalhttps://labs.leaningtech.com/blog/cheerpj-2-3-releasedhttps://labs.leaningtech.com/blog/cheerpj-2-3-releasedCheerpJ 2.3 is the only solution on the market to migrate real-world large-scale Java applications to modern HTML5 with pixel-perfect accuracy. Tue, 03 May 2022 00:00:00 GMTCheerpJReleasehttps://labs.leaningtech.com/blog/the-bottomless-pit-of-disappointment-a-chrome-extension-talehttps://labs.leaningtech.com/blog/the-bottomless-pit-of-disappointment-a-chrome-extension-taleHow Manifest V3 broke our Chrome extension, and how we are trying to fix it.Tue, 10 Aug 2021 00:00:00 GMTCheerpJTechnical