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nix-serve is a small utility to serve a Nix store as a binary cache, allowing it to be used as a substituter by other Nix installations.


The instructions below assume a flake-enabled version of Nix.

To start nix-serve, serving a binary cache on port 5000 of localhost:

# nix run github:edolstra/nix-serve

You can test whether the server works by running

# nix store ping --store http://localhost:5000

You can then pass --substituters http://localhost:5000/ to Nix to use this binary cache as a substituter.

nix-serve uses the Starman web server. See the starman documentation for additional flags you can pass, e.g.

# nix run github:edolstra/nix-serve -- --access-log /dev/stderr


It's possible to sign the binary cache. First create a key pair:

# nix-store --generate-binary-cache-key ./secret ./public
# cat public

Then run the server as follows:

# NIX_SECRET_KEY_FILE=./secret nix run ...

To check whether signing and signature verification works, do:

# nix verify --store http://localhost:5000 \
    --trusted-public-keys '' \

where /nix/store/... is one or more store paths served by your binary cache.