nix-bulkfetch-url

Fetch URLs, print hashes. No Nix store, parallel.

• Configurable worker pool (default: 16 concurrent downloads)
• Retries with exponential backoff (3 attempts by default)
• Fail-fast mode to bail on first error
• Zero dependencies, single static binary

Run directly without installing:

nix run github:z1-0/nix-bulkfetch-url

Or install permanently:

nix profile install github:z1-0/nix-bulkfetch-url

Add to your flake:

inputs.nix-bulkfetch-url.url = "github:z1-0/nix-bulkfetch-url";

NixOS system-wide (in configuration.nix):

environment.systemPackages = [
  inputs.nix-bulkfetch-url.packages.${pkgs.system}.default
];

Home Manager (in home.nix):

home.packages = [
  inputs.nix-bulkfetch-url.packages.${pkgs.system}.default
];

The binary itself has no Go dependencies. It is statically linked. Archive unpacking uses external tools:

Feed URLs via stdin, one per line. Lines starting with # and empty lines are ignored.

echo "https://example.com/archive.tar.gz" | nix-bulkfetch-url

echo "https://github.com/user/repo/archive/v1.0.0.tar.gz" | nix-bulkfetch-url

cat urls.txt | nix-bulkfetch-url -j 8 --json

Downloads each archive, extracts it, and computes a NAR hash on the unpacked directory. That is the same hash you would put in a Nix derivation's sha256 field.

cat urls.txt | nix-bulkfetch-url --unpack

grep -oP 'https://[^\s"]+\.tar\.gz' packages.nix | nix-bulkfetch-url --type blake3

cat urls.txt | nix-bulkfetch-url --json | jq '.[] | select(.error == null)'

1. Reads URLs from stdin
2. Downloads them concurrently using a pool of N workers
3. For each URL: fetches to a temp directory, unpacks if --unpack is set, then hashes with nix-hash
4. Prints one hash per line (or a JSON array with --json)