Show HN: Sonar – A tiny CLI to see and kill whatever's running on localhost

Source: Hacker News

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Know what’s running on your machine.

I got tired of running lsof -iTCP -sTCP:LISTEN | grep ... every time a port was already taken, then spending another minute figuring out if it was a Docker container or some orphaned dev server from another worktree. So I built sonar.

It shows everything listening on localhost, with Docker container names, Compose projects, resource usage, and clickable URLs. You can kill processes, tail logs, shell into containers, and more — all by port number.

$ sonar list
PORT   PROCESS                      CONTAINER                    IMAGE             CPORT   URL
1780   proxy (traefik:3.0)          my-app-proxy-1               traefik:3.0       80      http://localhost:1780
3000   next-server (v16.1.6)                                                               http://localhost:3000
5432   db (postgres:17)             my-app-db-1                  postgres:17       5432    http://localhost:5432
6873   frontend (frontend:latest)   my-app-frontend-1            frontend:latest   5173    http://localhost:6873
9700   backend (backend:latest)     my-app-backend-1             backend:latest    8000    http://localhost:9700

5 ports (4 docker, 1 user)

Install

curl -sfL https://raw.githubusercontent.com/raskrebs/sonar/main/install.sh | bash

Downloads the latest binary to ~/.local/bin and adds it to your PATH if needed. Restart your terminal or source ~/.zshrc.

Custom install location:

curl -sfL https://raw.githubusercontent.com/raskrebs/sonar/main/install.sh | SONAR_INSTALL_DIR=/usr/local/bin bash

Shell completions (tab-complete port numbers):

”${fpath[1]}/_sonar” # zsh sonar completion bash > /etc/bash_completion.d/sonar # bash sonar completion fish | source # fish”>sonar completion zsh > ”${fpath[1]}/_sonar” # zsh sonar completion bash > /etc/bash_completion.d/sonar # bash sonar completion fish | source # fish

Usage

List ports

sonar list # show all ports sonar list —filter docker # only Docker ports sonar list —sort name # sort by process name sonar list —json # JSON output sonar list -a # include desktop apps sonar list -c port,cpu,mem,uptime,state # custom columns sonar list —health # run HTTP health checks sonar list —host user@server # scan a remote machine via SSH

By default, sonar hides desktop apps and system services that listen on TCP ports but aren’t relevant to development — things like Figma, Discord, Spotify, ControlCenter, AirPlay, and other macOS .app bundles and /System/Library/ daemons. Use -a to include them.

Available columns: port, process, pid, type, url, cpu, mem, threads, uptime, state, connections, health, latency, container, image, containerport, compose, project, user, bind, ip

Inspect a port

sonar info 3000

Shows everything about a port: full command, user, bind address, CPU/memory/threads, uptime, health check result, and Docker details if applicable.

Kill processes

sonar kill 3000 # SIGTERM sonar kill 3000 -f # SIGKILL sonar kill-all —filter docker # stop all Docker containers sonar kill-all —project my-app # stop a Compose project sonar kill-all —filter user -y # skip confirmation

Docker containers are stopped with docker stop instead of sending signals.

View logs

sonar logs 3000

For Docker containers, runs docker logs -f. For native processes, discovers log files via lsof and tails them. Falls back to macOS log stream or Linux /proc//fd.

Attach to a service

sonar attach 3000 # shell into Docker container, or TCP connect sonar attach 3000 —shell bash # specific shell

Watch for changes

sonar watch # poll every 2s, show diffs sonar watch -i 500ms # faster polling sonar watch —notify # desktop notifications when ports go up/down sonar watch —host user@server # watch a remote machine

Dependency graph

sonar graph # show which services talk to each other sonar graph —json # structured output sonar graph —dot # Graphviz DOT format

Shows established connections between listening ports (e.g. your backend connecting to postgres).

Profiles

Save a set of expected ports for a project, then check if they’re all up or tear them down:

sonar profile create my-app # snapshot current ports sonar profile list # list saved profiles sonar profile show my-app # show profile details sonar up my-app # check which expected ports are running sonar down my-app # stop all ports in the profile

Port mapping

sonar map 6873 3002

Proxies traffic so the service on port 6873 is also available on port 3002.

Other

sonar open 3000 # open in browser sonar tray # system tray with live port list (macOS) sonar —no-color # disable colors (also respects NO_COLOR env)

Supported platforms

• macOS (uses lsof)

• Linux (uses ss)