faster

README

faster

A tiny, dependency-free Go clone of fast-cli — an internet speed test using Netflix's fast.com infrastructure.

It scrapes fast.com's rotating API token, asks the fast.com API for CDN targets, then saturates them with parallel connections and reports the steady-state throughput.

Install

go install github.com/yavosh/faster@latest

This drops a faster binary in $(go env GOPATH)/bin (make sure that's on your PATH).

Or build from source:

git clone https://github.com/yavosh/faster
cd faster
go build -o faster .

Usage

faster                 # download speed, live, with latency
faster -upload         # also measure upload
faster -json           # machine-readable output
faster -simple         # just the download number in Mbps (for scripts)

Flags

Flag	Default	Description
-upload	false	Also measure upload speed
-json	false	Emit results as JSON (download/upload/latency/client)
-simple	false	Print only the download speed in Mbps
-avg	false	Report cumulative average rate instead of steady-state
-conns	5	Number of parallel connections
-bytes	26214400	Payload size per request in bytes
-timeout	30s	Max duration per measurement

Examples

# Steady-state download over 8 connections
faster -conns 8

# Log a JSON line to a file
faster -json -upload >> speedlog.jsonl

# Just the number, e.g. for a status bar
faster -simple

How it works

1. Token — fetches fast.com, finds the app-*.js bundle, extracts the token:"…" embedded in it (the token rotates, so it's re-fetched each run).
2. Targets — calls https://api.fast.com/netflix/speedtest/v2?token=… for a list of CDN endpoints.
3. Measure — parallel workers stream /range/0-N payloads (or POST for upload) into a shared atomic byte counter; a sampler reports the smoothed instantaneous rate and stops once it plateaus (±2%) or the timeout hits.

By default faster reports the steady-state rate (what the live line settles on, matching fast.com's UI). Pass -avg for the cumulative average over the whole run.

Notes

• This relies on an unofficial, undocumented endpoint that can change without notice.
• Numbers are in megabits per second (Mbps).

License

MIT