Ant JavaScript Runtime: A Lightweight, Sandboxed Ecosystem

Ant is a lightweight, high-performance JavaScript runtime designed to minimize overhead and maximize security. It features a hand-built engine, Ant Silver, which allows the runtime to operate from a single 9.1 MB binary without requiring a complex toolchain or the massive footprints of V8, JavaScriptCore, or SpiderMonkey.

High-Performance Execution and Cold Starts

Ant focuses on reducing initialization overhead to achieve faster cold starts than existing major runtimes. In internal benchmarks, the time to import Hono, register two routes, and exit—isolating module resolution and initialization—was 5.4 ms, significantly faster than Bun (12.8 ms), Deno (24.8 ms), and Node.js (31.1 ms).

Native TypeScript Support

Ant eliminates the need for a build step for TypeScript. Developers can run .ts files directly using ant app.ts, removing the requirement for tsc or external bundlers and dist folders.

Package Management

Ant includes a built-in package manager that claims to be up to 40x faster than npm. For example, installing the hono package takes approximately 155ms.

Security via VM-Isolated Sandboxing

One of Ant's most distinctive features is its integrated VM-isolated sandbox. Unlike simple permission prompts, Ant provides a hard boundary for running untrusted JavaScript. Each sandbox is its own KVM / Hypervisor.framework VM, providing hardware-level isolation.

Key security constraints include:

• Read-only Mounts: Filesystem mounts are immutable by default unless explicit write access is granted.
• Network Isolation: The runtime employs a "deny-all" policy by default, forwarding only specifically named ports.

The Ant Ecosystem and Registry

Ant introduces ants.land, an open registry that speaks the npm protocol. This allows packages to be published and installed by scope or bare name, and enables packages to be used directly in the browser via esm.ants.land.

Community Discussion and Technical Critique

Community members on Hacker News have highlighted several points of interest and technical concerns regarding the Ant runtime:

Performance and Provenance

While Ant claims "near-V8 speeds," some users pointed out that external benchmarks (such as zoo.js) suggest a performance gap. There are also discussions regarding the provenance of the engine, with one user noting that early versions of the project may have been based on an AGPL codebase (Elk), though the author has since stated the project has been rewritten.

Use Cases and Value Proposition

• Embedding: Users expressed interest in using Ant's small binary size for embedding purposes, where dragging along a large V8 instance is prohibitive.
• FaaS: The quick startup times and sandboxing make Ant a potential foundation for Function-as-a-Service (FaaS) systems.
• Supply Chain Security: The sandboxing capabilities are praised as a critical tool for mitigating supply chain attacks and worms.

Naming and Ecosystem

Some users questioned the naming choice, noting the a potential conflict with Apache Ant, the Java-based build tool.

"Why call it "Ant" and not "Antjs" or "Ant.js" when there is already Ant from Apache?"

Practicality of Binary Size

One user questioned the value of a 9 MB binary compared to the rest of the JS ecosystem's heavier weight:

"What is a 50mb runtime you down once next to a 200mb node_modules?"

Installation and Compatibility

Ant is available for macOS and Linux on arm64 and x86_64 architectures, requiring no external toolchain for installation.