jsed — a JSON editor for large files

A project to build a JSON editor in Rust that comfortably handles files over 100 MB.

Install (macOS, Apple Silicon)

The easiest way to install jsed is via Homebrew:

brew install Kemosabert/tap/jsed

Then run it from anywhere:

jsed ~/path/to/file.json   # opens the file on startup
jsed                       # opens the empty app; use File > Open

To upgrade later: brew upgrade jsed. To uninstall: brew uninstall jsed.

jsed accepts an optional file path as its first argument, so you can launch it on any JSON file from the shell regardless of your current directory.

Builds are currently published for Apple Silicon Macs only.

Prerequisites

Install the Rust toolchain (includes rustc and cargo):

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

After install, restart your shell or source "$HOME/.cargo/env". Verify:

rustc --version   # should be 1.75 or newer
cargo --version

No other system dependencies needed on macOS — the glow backend uses OpenGL which is built into the OS.

Project layout

json-editor/
├── Cargo.toml          # workspace manifest
├── core/               # pure-logic crate (no UI deps)
│   ├── Cargo.toml
│   └── src/lib.rs      # Document, loading, (later) formatting, search
└── gui/                # egui-based desktop app
    ├── Cargo.toml
    └── src/main.rs

The split is deliberate: the core crate stays testable with plain cargo test, and when we later swap the GUI framework or add a CLI, the engine doesn't change.

Run it

# From the repo root
cargo run --release -p jsed-gui

# Or pass a file to open immediately:
cargo run --release -p jsed-gui -- ~/path/to/file.json

The first build will take 1–3 minutes while it compiles eframe and its dependencies. Subsequent builds are incremental and fast.

Use --release even during development — egui is noticeably smoother with optimizations on, and the workspace is configured to always optimize dependencies anyway so recompilation of our own code stays fast.

Test it

cargo test -p jsed-core

All tests live in the core crate for now, since the logic worth testing is there.