faster-cli

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Measure the speed of your internet connection from the terminal.

$ fast
Latency    204.6 ms (±20.5 ms jitter)
Download   3.8 Mbps
Upload     9.9 Mbps

Install

With a Rust toolchain:

cargo install faster-cli

Usage

fast                  # latency, download and upload
fast --download-only  # skip the upload phase
fast --json           # one JSON object, for scripts
fast --verbose        # also show which server answered

Attached to a terminal, the current rate is drawn full screen while the test runs. Piped or redirected, nothing is printed until the result is ready, so fast --json > result.json gives you exactly the object and nothing else.

Exit codes are 0 on success, 1 on failure, 2 for a bad argument and 130 if you interrupt it with ctrl-c.

JSON output

--json always includes every field, whether or not --verbose is given. A skipped upload is null rather than an absent key, so jq expressions keep working across both modes.

{
  "server": { "host": "speed.cloudflare.com", "colo": "MAD" },
  "client": { "ip": "203.0.113.7", "country": "ES" },
  "latency_ms": 13.4,
  "jitter_ms": 1.2,
  "download_mbps": 243.8,
  "downloaded_bytes": 304750000,
  "upload_mbps": 41.2,
  "uploaded_bytes": 51500000,
  "duration_s": 21.3
}

Rates are rounded to two decimals. The byte counts and duration are exact, so you can recompute a rate at full precision if you need to.

Development

cargo test
cargo clippy --all-targets -- -D warnings
cargo run -- --verbose

License

MIT