LLRT (Low Latency Runtime) is a lightweight JavaScript runtime designed for fast, resource-efficient serverless applications.
It is particularly focused on short-lived workloads running on AWS Lambda, where startup latency and memory consumption can have a significant impact.
The runtime is written in Rust and uses QuickJS as its JavaScript engine. Unlike Node.js, Deno and Bun, LLRT does not use a just-in-time compiler. This reduces the runtime’s size and avoids JIT compilation overhead, helping small serverless functions start quickly.
LLRT supports ES2023, ECMAScript modules, CommonJS modules, asynchronous programming and selected Node.js and Web Platform APIs. It also includes optimized AWS SDK for JavaScript clients within its standard and full SDK builds.
LLRT is experimental and is not intended to be a drop-in replacement for Node.js. It is best suited to relatively small functions handling tasks such as data transformation, authorization, validation, event processing and AWS service integration.
This is free and open source software.
Key Features
- Lightweight JavaScript runtime optimized for serverless workloads.
- Written in Rust and powered by the QuickJS JavaScript engine.
- Avoids JIT compilation to reduce startup and memory overhead.
- Supports the ES2023 JavaScript specification.
- Supports ECMAScript and CommonJS modules.
- Provides selected Node.js-compatible APIs.
- Implements a range of Web Platform APIs.
- Includes optimized AWS SDK for JavaScript clients and utilities.
- Offers no-SDK, standard-SDK and full-SDK builds.
- Supports asynchronous functions and promises.
- Includes a built-in Jest-like test runner with Jest and Chai assertions.
- Supports unit, end-to-end and Web Platform tests.
- Can be deployed as an AWS Lambda custom runtime or Lambda layer.
- Supports deployment through container images, AWS SAM and AWS CDK.
- Available for ARM64 and x86-64 architectures.
- Can also be built for local Linux and macOS systems.
Website: github.com/awslabs/llrt
Support:
Developer: Amazon Web Services
License: Apache License 2.0
LLRT is written in Rust. Learn Rust with our recommended free books and free tutorials.
Related Software
| JavaScript Runtime Environments | |
|---|---|
| Node.js | Hugely popular cross-platform JavaScript run-time environment |
| Bun | Fast JavaScript runtime designed as a drop-in replacement for Node.js. |
| Deno | Simple, modern and secure runtime for JavaScript and TypeScript that uses V8 |
| WasmEdge | High-performance, and extensible WebAssembly runtime |
| txiki.js | Small and powerful JavaScript runtime |
| JerryScript | JavaScript engine for the Internet of Things |
| Window.js | JavaScript runtime for desktop graphics programming |
| Blueboat | Multi-tenant serverless JavaScript runtime |
| lo | Successor project to Just |
| Just | Very small v8 JavaScript runtime |
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