Moddable 2025

January 9, 2025 | Peter Hoddie, Principal

Moddable 2025

While we try to focus on what's next for Embedded JavaScript, once a year the Moddable team reflects back on the progress we've made. In 2025, AI was everywhere, including the Moddable SDK. We also began porting to a new RTOS, deepened our support for standard Embedded JavaScript APIs, stayed up-to-date with the ESP-IDF, and much more. Read on to learn how these improvements can benefit your projects and for a glimpse of what's in store for 2026.

AI

AI has many different facets. Here are some of the ways the Moddable SDK is helping developers benefit from the rapid advances in AI.

chatAudioIO API

chatAudioIO is an all-new API for interactive voice chats with LLMs from OpenAI, Google, ElevenLabs, Hume.ai, and Deepgram. The API takes care of real-time streaming, audio playback, and audio capture with remarkable efficiency thanks to careful optimization that includes a dedicated streaming JSON parser and audio decoders.

There's a tiny example app that shows just how you can add interactive voice chat to your project with fewer than 20 lines of JavaScript.

chatAudioAI also allows your app to provide functions for the LLM to invoke, such as reading a sensor in response to a prompt. There's an example for that as well.

conversationalAI App

conversationalAI is an all-new app that provides a dynamic, mobile-like user experience for interactive voice chats with LLMs. Unsurprisingly, conversationalAI builds on our new chatAudioAI API. The app runs on Moddable Six and other ESP32 development boards, and on computers using the Moddable SDK simulator.

Helping LLMs Learn from the Moddable SDK

LLMs learn from the source code of the Moddable SDK to be able to answer your questions. The easier it is for the LLM to understand that source code, the more easily it can learn. To call native C functions from JavaScript, the Moddable SDK has used a non-standard syntax that can trip up LLMs (and tools like eslint and TypeScript). We've designed and implemented a new syntax to integrate with native code that is 100% standard JavaScript. Experience has shown that our New Native API is easily understood by LLMs and JavaScript developers alike.

Zephyr Port

The Moddable team has had its eye on the Zephyr RTOS for years, and Embedded JavaScript developers have regularly asked about supporting Zephyr. In 2025, we decided it was time to undertake a port to Zephyr.

Zephyr is the RTOS from the Linux Foundation. It supports a wide range of silicon platforms with lightweight C APIs. That portability is a perfect fit for Embedded JavaScript, especially ECMA-419 APIs which are also designed to support a wide range of silicon. We have a robust Zephyr port in place that is quickly evolving - check our launch post, first progress report, and second progress report.

ECMA-419 Standard

Moddable has played a leading role in the creation of ECMA-419, the ECMAScript Embedded Systems API Specification. This collection of thoughtfully designed APIs is vendor-neutral, efficient, extensible, and consistent. 2025 brought the 3rd Edition of ECMA-419, and work is underway on the 4th Edition.

In 2025, the Moddable SDK added all-new Bluetooth Client (Central) and Server (peripheral) APIs based on ECMA-419. These allowed the Moddable SDK to support Web Bluetooth for Embedded JavaScript developers for the first time, dramatically simplifying and standardizing communication with Bluetooth peripherals.

Moddable is deeply committed to adopting ECMA-419 throughout the Moddable SDK. Our new chatAudioIO API uses ECMA-419 APIs exclusively for network communication, audio capture, and audio playback. Our new Zephyr port is our very first port to support ECMA-419 exclusively, omitting support for earlier APIs.

Endless Improvements

There have been hundreds of improvements to the Moddable SDK in 2025. The best way to keep up is to read our release notes, published near the start of each month. The release notes go beyond a simple list of changes to introduce new features and techniques to accelerate your development. Here are a few highlights from our twelve releases in 2025:

  • ES2025. Every year a new version of the JavaScript language standard (ECMAScript) is released. Moddable's XS engine implements ES2025, the latest standard, bringing the modern programming language of the web to embedded devices.

  • Piu memory optimizations. Piu is our user interface framework. Our conversationalAI app is built on Piu. We reduced the RAM needed for Piu objects across all devices, freeing up precious memory for your project.

  • TypeScript. Moddable continues to deepen our support for TypeScript, a popular choice of Embedded JavaScript developers. Our New Native API makes it possible for the first time to bind TypeScript to native C code in the Moddable SDK. We've also made a major update to our typings to cover many more uses.

  • ESP-IDF updates. The most popular MCU with Embedded JavaScript developers is the ESP32 family. We updated the Moddable SDK in 2025 to support ESP-IDF 5.4 and later 5.5.1, ensuring Embedded JavaScript developers have the latest improvements from Espressif available.

  • Security and stability. Moddable tests our XS JavaScript 24/7 using Fuzzilli and oss-fuzz. As issues are discovered, Moddable integrates fixes into Moddable SDK releases. These make projects built with Moddable SDK even more robust and resilient against attacks by JavaScript code.

Moddable Six: More Power You Can Use

Moddable builds embedded hardware specifically designed for Embedded JavaScript developers. In 2025, we released an update to our sold-out Moddable Six that adds a microphone and significantly improves audio quality, while keeping a price that starts at just $29.99. Moddable Six includes a dual-core ESP32-S3 MCU, Wi-Fi, Bluetooth, and a high-performance touch screen.

Moddable Six is a great hardware platform for our new conversationalAI app. And you won't find a more powerful development board for getting started with Embedded JavaScript. And because every hardware feature is accessible from JavaScript, you can easily use all that power.

Onward to 2026

Our successful 2025 sets the stage for 2026. Here's some of what we expect in 2026:

  • ES2026. JavaScript continues to evolve, and Moddable continues to bring that to Embedded JavaScript developers.

  • Zephyr. Our Zephyr port will continue to add new features and will migrate from a branch to main.

  • TypeScript. We hope to make developing with TypeScript even easier and more valuable for Embedded JavaScript developers.

  • ECMA-419. We continue to work on migrating the Moddable SDK to these industry-standard APIs and phasing out the original APIs they supplant.

  • Another platform. We've got our eyes on a beloved platform that would benefit from standard Embedded JavaScript. Stay tuned.