Rust Code Viewer
Paste Rust to get syntax highlighting, an outline of every item the file declares, and a delimiter check — all in your browser. It does not compile or run Rust, and links to the official Rust Playground when you need to.
Programming Language ToolsHow to use Rust Code Viewer
- Paste Rust source into the editor.
- The highlighted view appears beside it, with line numbers.
- Read the outline to see every fn, struct, enum, trait, impl and mod the file declares.
- Check the delimiter status: an unclosed brace is reported with the line it was opened on.
- Press Open in Rust Playground to compile and run the snippet on the official site.
Examples
What the outline shows
Every item declaration is listed with its kind and line, which makes a long file quick to navigate.
struct Tool L6 impl fmt::Display L13 trait Describe L19 fn group L30 fn main L38
Lifetimes and attributes
Highlighting distinguishes lifetimes from character literals, which most generic highlighters get wrong.
#[derive(Debug, Clone)]
pub struct Tool<'a> { pub name: &'a str }Features
- Rust-aware highlighting: keywords, types, lifetimes, attributes, macros, strings and comments
- Outline of declared items with their line numbers
- Delimiter check that reports the line an unclosed brace was opened on
- Handles raw strings, block comments and character literals correctly
- Copy the source or download it as main.rs
- One click to send the snippet to play.rust-lang.org
- Autosaves your draft to this browser only
Frequently asked questions
- Can this run my Rust code?
- No, and it will not pretend to. Compiling Rust needs the real toolchain, which has no browser-sized build. The Open in Rust Playground button sends your snippet to the official playground, which does have a compiler behind it.
- Why is there no Rust formatter here?
- rustfmt has no WebAssembly build that works in a browser today. Rather than ship a regular-expression imitation that would mangle real code, this tool does what can genuinely be done client-side. If a reliable browser build of rustfmt appears, formatting will be added.
- What does the delimiter check catch?
- Unbalanced braces, brackets and parentheses outside strings and comments — the most common reason a file fails to compile after an edit. It reports the line the unclosed delimiter was opened on, which is usually far from where the compiler complains.
- Is the outline a full parse?
- No. It recognises item declarations — fn, struct, enum, trait, impl, mod, type and macro_rules! — at the start of a line. That covers normal Rust layout; heavily macro-generated code may declare items it cannot see.
- Does my code leave the browser?
- Only if you press Open in Rust Playground, which by design sends the snippet to play.rust-lang.org. Everything else happens locally.
- Can I use it to review a file quickly?
- That is what it is for: paste a file, read the outline to see its shape, and use the highlighting to scan it, without cloning a repository or opening an editor.
Related tools
About Rust Code Viewer
Rust Code Viewer is part of Programming Language Tools on ToolHive, a growing collection of small, focused utilities for developers, designers and students. Formatters and playgrounds for Python, C, Java, Go, Rust and SQL. Everything runs client-side, so your data never leaves the browser tab — which makes these tools safe to use with work-in-progress code and private content.