nix-du

An ncdu-like terminal UI for exploring Nix store derivation sizes.

• Fast analysis: reads the Nix store SQLite database (/nix/var/nix/db/db.sqlite) directly, then computes closure sizes in memory
• ncdu-style navigation: arrow keys or hjkl, enter to drill into references, h to go back
• Derivation index: top-level groups by package name prefix (e.g. python3, linux, source)
• Sortable: by closure size (s) or name (n)
• Visual bars: optional relative size graph (g)

Sizes are NAR closure sizes — the serialized size of a path plus everything it references.

• A local Nix store with a readable /nix/var/nix/db/db.sqlite (the default on NixOS and multi-user installs)
• A Rust toolchain (1.74+)

Run it directly from GitHub without cloning:

nix run github:arsfeld/nix-du

Or, from a checkout of this repo:

nix run

Or build the binary and run it:

nix build        # produces ./result/bin/nix-du
./result/bin/nix-du

With Cargo:

cargo run --release

Browse a specific store path's references instead of the derivation index:

cargo run --release -- /nix/store/…-firefox.drv

For a development shell with rustc, cargo, clippy, and rustfmt:

nix develop

Each row shows the closure size, a relative size bar, the percentage of the current view's total, a reference count, and the entry name. The leading marker indicates the entry type:

• The initial scan reads the store database directly and is fast — a few seconds even on large stores.
• The database is opened read-only; nix-du never writes to it.
• Group totals sum derivation closure sizes and may double-count shared dependencies.
• Only paths present in the local store are included.

MIT