WinterJS
Claim this toolBlazing-fast JavaScript server for Service Workers, built for high performance.
Free, no paid tier Visit Website Free Visit Website
Tracked since 2026
The Bottom Line
- Price
- Free, no paid tier. Compare plans
Key facts
- A blazing-fast JavaScript server running WinterCG-compliant Service Workers.
- Achieves high performance, handling up to 100,000 requests/second.
- Built with SpiderMonkey, Spiderfire, and Hyper, with WASIX support.
Pros
- Extremely high performance for JavaScript server-side applications
- Compliance with WinterCG specification provides a standardized environment
- Leverages established and performant technologies like SpiderMonkey and Hyper
- Open-source with an MIT license
- Supports a wide range of standard web APIs for server-side use
Cons
- Building from source requires complex steps, including SpiderMonkey compilation
- WASIX compilation is currently a complex process
- Some APIs are partially implemented or pending, indicating ongoing development
What is WinterJS?
WinterJS is a high-performance JavaScript server designed to run Service Worker scripts according to the Winter Community Group (WinterCG) specification. It leverages SpiderMonkey, Spiderfire, and Hyper to achieve exceptional speed, capable of handling up to 100,000 requests per second on a single laptop. This makes it ideal for developers building server-side applications that require high throughput and low latency, particularly those familiar with or looking to utilize the Service Worker API on the server.
The product is geared towards developers who need a robust and efficient JavaScript runtime for server-side logic, especially in environments where WebAssembly (WASM) compilation is beneficial. While it supports WASIX for WebAssembly compilation, the project recommends using precompiled versions for simplicity. WinterJS aims to provide a fully compliant WinterCG runtime, offering a familiar environment for web developers extending their skills to the backend.
Available on: Web, macOS, Linux
Preview
Key Features
- WinterCG specification compliance
- High-performance HTTP server (100,000 reqs/s)
- SpiderMonkey JavaScript engine integration
- Spiderfire and Hyper for underlying architecture
- WASIX standard for WebAssembly compilation
- Supports `fetch`, `Response`, `Request`, `URL`, `Headers`
- Includes `console`, `performance`, `crypto` APIs
- Supports `ReadableStream`, `WritableStream`, `TransformStream`
Pricing
Free
WinterJS is completely free to use with no hidden costs.
WinterJS by the numbers
| Metric | WinterJS | Peer median | Position (1 is best) |
|---|---|---|---|
| Free plan | Yes | 10 of 19 have one | n/a |
| Listed as an alternative to | 1 tool | 2 | #11 of 19 (joint) |
Each position is counted among the tools that have data for that row, as noted under it. All Edge Computing data · How we compute this. Advertising and placement fees are not inputs to any position.
Cite this: Toolradar, “WinterJS by the numbers”, Oct 2026.
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WinterJS FAQ
How does WinterJS achieve its high performance for JavaScript server applications?
WinterJS achieves blazing-fast performance by leveraging established and performant technologies such as SpiderMonkey, Spiderfire, and Hyper. This architecture allows it to handle up to 100,000 requests per second on a single laptop, making it suitable for high-throughput and low-latency server-side applications.
Which teams would benefit most from using WinterJS?
WinterJS is best suited for developer teams who require a robust and efficient JavaScript runtime for server-side logic, especially those familiar with the Service Worker API. It is ideal for applications needing high throughput and low latency, particularly in edge computing environments.
How is WinterJS priced?
WinterJS is free to use, as it is an open-source project released under an MIT license. There are no paid plans required to utilize its features.
What kind of server-side applications can be built with WinterJS?
WinterJS is ideal for building server-side applications that require high throughput and low latency, utilizing the Service Worker API. Its performance characteristics make it suitable for scenarios in hosting, deployment, and edge computing where efficient JavaScript execution is critical.
What are the main trade-offs when choosing WinterJS for a project?
A main trade-off for WinterJS is that building it from source can be complex, requiring steps like SpiderMonkey compilation. Additionally, while it supports WASIX for WebAssembly compilation, this process is currently complex, and some APIs are still partially implemented or pending.
How does WinterJS compare to Cloudflare Workers?
WinterJS provides a high-performance JavaScript server for Service Workers, built on SpiderMonkey and Hyper, offering a fully compliant WinterCG runtime. Like Cloudflare Workers, it enables server-side JavaScript execution, but WinterJS focuses on an open-source, self-hostable solution for extreme performance.
Does WinterJS support standard web APIs for server-side use?
Yes, WinterJS supports a wide range of standard web APIs for server-side use, providing a familiar environment for web developers. This compliance with the Winter Community Group (WinterCG) specification ensures a standardized runtime.
Source: winterjs.org