Ant

Ant is a JavaScript runtime built from scratch that aims to carry more than it weighs. It runs real npm packages, starts almost instantly, and ships as a portable binary of around nine megabytes. There's no fifty megabyte download and no toolchain to set up first, so getting from nothing to running a file is meant to take seconds rather than an afternoon of configuration.

The part that sets it apart from most alternatives is the engine underneath. Ant runs on a hand-built engine called Ant Silver, and it isn't a wrapper around V8, JavaScriptCore, or SpiderMonkey. Building the engine rather than borrowing one is an unusual choice, and it's what lets the project chase a small binary and fast startup without inheriting the bulk of a browser-grade engine. The makers report a full pass on the compat-table and conformance with WinterTC, so the goal isn't a stripped-down dialect, it's the ecosystem you already write. The compatibility claim isn't only about npm installs. The site lists frameworks and tools it runs, including Hono, Elysia, TypeScript, React, Rolldown, and Wasm, and it targets WinterTC as the standard for server-side JavaScript. Running the ecosystem you already use is the whole pitch, because a fast runtime that can't run your existing code isn't much use, and the project leans on standards conformance rather than a bespoke API to get there.

Speed shows up in two places that developers feel every day. Cold start is quick, and the project publishes a benchmark that imports Hono, registers two routes, and exits, isolating module resolution and startup rather than server throughput. In that test Ant comes in fastest against Bun, Deno, and Node. Installing packages is fast too, with a built-in installer the makers describe as up to forty times faster than npm, so pulling in a dependency finishes in a fraction of a second with no extra tooling to wire up. Real frameworks work without adapters. Ant serves a default fetch export, which means you can write a Hono handler, run the file, and have a server listening without gluing on a bridge. TypeScript runs directly as well, so instead of compiling to a dist folder and then running the output, you point Ant at the .ts file and it runs. That removes a build step that most projects otherwise carry around by default.

Security is treated as a first-class feature rather than a prompt you click through. Ant ships with a VM-isolated sandbox, where each sandbox is its own hardware-backed virtual machine using KVM or the Hypervisor framework. You mount the filesystem read-only unless you explicitly grant writes, network access is deny-all until you name the ports you want forwarded, and untrusted code runs behind a hard boundary. For anyone running code they didn't write, that's a stronger stance than a permission flag.

There's an ecosystem story too. Packages live on ants.land, an open registry that speaks the npm protocol, so what you publish installs by scope or by bare name and works across common package managers. Packages can also load straight in the browser from the registry's ESM endpoint. Publishing is a couple of commands, and the registry scores packages on documentation, license, and compatibility. That scoring is a small but useful touch. Each package carries a rating from zero to one hundred drawn from its documentation, license, and compatibility, which gives a quick read on quality before you pull something in. Because the registry speaks the npm protocol, packages install by scope or bare name across the common package managers rather than being locked to Ant, and they can load directly in a browser from the registry's ESM endpoint, so the same package can serve a server script and a browser experiment without repackaging.

Ant is aimed at developers who want a fast, portable runtime for servers, scripts, and TypeScript without a heavy install or a build pipeline, and at anyone who needs to run untrusted JavaScript inside a real isolation boundary. It's a young project, publicly documented through 2026 with write-ups on how it was built, and the source lives on GitHub under a public repository. Installation is a single curl command, it targets macOS and Linux on both arm64 and x86_64, and because the source is open you can read, self-host, and build on it rather than treating it as a closed binary.

It's worth being clear about maturity. Ant is new, documented publicly through 2026 with write-ups covering how the runtime was built in about a month and where it went next, which signals a project moving quickly rather than a finished, settled tool. A custom engine also means it hasn't had the years of adversarial use that V8-based runtimes have behind them, so it reads best as a fast, promising runtime to try on new work rather than a drop-in replacement for a large production system on day one.