Install and first response

Install

Three ways to get apimock:

# via npm, into an existing project
npm install -D apimock-rs
npx apimock

# via cargo, as a standalone binary
cargo install apimock
apimock

# via a prebuilt binary — no Node or Rust toolchain needed
# download from https://github.com/apimokka/apimock-rs/releases/latest
tar xzf 'apimock@Linux-x64-gnu-<version>.tar.gz'
cd 'apimock@Linux-x64-gnu-<version>'
./apimock

Whichever you choose, the command you run afterward is apimock (the package on npm is named apimock-rs, but the binary it installs is apimock).

Which prebuilt archive

⬇️ Download from the latest release, then pick the archive for your platform:

Each archive unpacks to a directory containing the binary plus an apimock.toml, apimock-rule-set.toml and apimock-middleware.rhai. Run ./apimock from that directory and it loads them automatically — no -c flag and no apimock --init step — so a downloaded build is already serving the example rules:

curl http://localhost:3001/health   # --> ok
curl http://localhost:3001/greet    # --> Hello, world.

That also means a downloaded build is ready for the config-file walkthrough as it stands.

Zero configuration needed

Run apimock in an empty directory and it starts immediately — no config file required:

apimock
# Listening on http://127.0.0.1:3001 ...

At this point, every request 404s, because there’s nothing to serve yet.

Your first response

Drop a JSON file into the directory apimock is running from:

mkdir -p api/v1/
echo '{"hello": "world"}' > api/v1/hello.json

Restart apimock (or start it now, if it wasn’t already running), then request the path matching that file — the .json extension is optional:

curl http://localhost:3001/api/v1/hello
# --> {"hello":"world"}

You can check the same thing in a browser at http://localhost:3001/api/v1/hello.

That’s file-based routing: the URL path maps directly to a file path. A directory request (/, /api, /api/v1) looks for an index.json / index.json5 / index.csv / index.html file and 404s if none exists. .json5 files are treated the same as .json; .csv files are converted to a JSON array of rows.

Next: Your first config file, for responses that depend on more than just the URL path.