blaze

What you get

• Live edits. Save a file and the running program has the new code about a millisecond later. Its state stays.
• Fast builds. After the first build, an edit rebuilds only the functions you changed. No rustc, no waiting.
• Same commands as cargo. blaze build|run|test|check in any project, or cargo blaze build and so on.

How fast

Edit one function, then build. 200-crate workspace, median of three.

Benchmark history: every run on real projects, next to plain cargo.

Try it

nix run github:indexable-inc/blaze#blaze -- build

Use it as your normal cargo build

nix profile install github:indexable-inc/blaze#blaze
cargo blaze enable

Plain cargo build, run, test and check then go through blaze. cargo blaze disable undoes it.

Live edits

ra-jit-live = { git = "https://github.com/indexable-inc/blaze" }

let mut live = ra_jit_live::Live::start().ok();
loop {
    if let Some(outcome) = live.as_mut().and_then(|it| it.poll()) {
        eprintln!("blaze: {outcome}");
    }
    // ...your frame
}

What to know

• Live edits: macOS Apple silicon only. Elsewhere you still get fast builds.
• No borrow checker: keep running cargo check.
• Rust 1.99.0 only.
• Changing a struct the program is using asks for a restart.

More: how it works, full results, what is supported, GitHub.

Where it is going

blaze is a superset of Rust. What it adds, it adds in the open: the charter says what we hold to, and the RFCs are the designs being argued about. Sign in with GitHub to comment on any paragraph.

Credits

blaze stands on the shoulders of giants. Thank you to the people who built rust-analyzer, Cranelift, LLVM and inkwell, salsa, object, Rust, and rustd (DioxusLabs), whose code blaze includes. None of these projects endorses blaze. blaze was called ra-jit until 2026-10-24, and cargo ra-jit still works. Made at ix for den's native app. MIT or Apache-2.0. This site is Flecs scripts, run under Flecs compiled to wasm.