alt.hn

3/20/2026 at 9:59:56 AM

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

 https://github.com/RasKrebs/sonar

by raskrebs

3/20/2026 at 7:46:11 PM

Hey, thanks for sharing this. Your app inspires me to take a look at Go, again! I've been searching for another primary language to learn. My primary used to be Java at $day$ job and now Python for ML/AI. I love Python but still feel insecure given the lack of static typing. I look at TypeScript as well, especially in the context of Bun runtime. I decided it may not be for me, not the language, but the ecosystem around it.

by mrbonner

3/20/2026 at 7:57:03 PM

I quite like go for how lean it is, really nice for local projects with lots of constant changes. Also easy to learn. The biggest most annoying thing is how bad error handling is done, not sure why they built it like that.

I primarily write typescript and python for work. But have dabbled in bunch of other languages at different jobs and for different tasks. Yet to pick up rust, but have been wanting to. But tend to pick what seems most right for the task, while also considering what i most want to be working with

by raskrebs

3/20/2026 at 8:15:53 PM

I forgot that I also "try" Rust as well. But, I feel like it may not be suitable for my use cases and not simple enough for non-intelligent person like me :-). I agree error handling in Go could be better. But, comparing to Java I don't think I would feel salty.

by mrbonner

3/20/2026 at 12:46:59 PM

Would be nice to have a flag to customize the URL displayed for Docker containers. I connect to my host via Tailscale, but I can’t open links with localhost. It would be helpful to have a parameter that allows us to choose a network device or specify an IP address to display.

    3000    wud (getwud/wud:latest)                            wud          getwud/wud:latest                       3000    http://localhost:3000
    3001    dockhand (fnsys/dockhand:latest)                   dockhand     fnsys/dockhand:latest                   3000    http://localhost:3001

by klaushardt

3/20/2026 at 2:51:28 PM

Nice! I always forget the lsof flags and end up googling them every time. Would be cool if it could run in the system tray and show what's running on your ports at a glance. Also, the name had me thinking SonarQube at first, might be worth considering a rename to avoid the confusion.

by maciejj

3/20/2026 at 4:39:05 PM

Someone else added an issue about this, and i replied explaining how to run the feature branch, have a look and please add any ideas to the issue:

https://github.com/RasKrebs/sonar/issues/15

by raskrebs

3/20/2026 at 2:55:11 PM

[dead]

by raskrebs

3/20/2026 at 4:52:51 PM

We live in crazy times. I wanted to add a PID to the list for my personal use and since I use Rust way more than Go, I decided to one-shot one app, and Codex indeed one shotted it, wow.

https://github.com/fcoury/sonars

by fcoury

3/20/2026 at 6:05:30 PM

I'm tempted to one-shot this into a series of FISH abbreviations.

And I would want someone to use that to one-shot a python implementation. And on and on like a game of telephone until the context degrades so far that it becomes an entirely different program.

by zenoprax

3/20/2026 at 4:58:08 PM

You can add PID with the c-flag, e.g.

sonar list -c port,process,pid,type,url,container

or just show all columns:

sonar list --all-columns

But yeah, it's quite cool. I believe the future lies in software distillation, so cool to see it happen on my own project :D

by raskrebs

3/20/2026 at 5:28:08 PM

I did this more as an experiment but man it sucks, doesn't it?

by fcoury

3/20/2026 at 6:40:42 PM

What sucks? Software distillation? :)

by raskrebs

3/20/2026 at 9:59:56 AM

I always have a bunch of local projects running, particularly during the weekend where I'm rarely working on one thing at a time. A big pain of mine was constantly running into port: Redis from one project blocking another, orphaned dev servers from old worktrees, Docker containers I forgot about. The usual fix is lsof -iTCP | grep ..., then figuring out what the PID actually is, then killing it. But I always forget the command, and it doesn’t really include all the information that I like.

So I built this lightweight CLI. Single binary, no dependencies. It shows everything listening on localhost with process names, Docker container info, clickable URLs etc.

Sure there are workarounds, but none that satisfied my need for a short, easily rememberable command. Also nothing really has the same satisfaction as running sonar kill 3000 — it just feels nice. I’ve already been approached by a few agent orchestration tools that have been struggling with the same thing. It's really useful when you have multiple agents running, but it's not built for just that use case, I have also find it handy when killing off all containers after a failed cleanup and so on. Also know that MCPs are dead and CLIs are the new thing in agentic coding, this might be a useful tool for Claude, particularly when a compose process exits before all containers are stopped.

Open for contributions, ideas and feedback.

by raskrebs

3/20/2026 at 12:48:29 PM

> I’ve already been approached by a few agent orchestration tools that have been struggling with the same thing

Wow, this says more about the agent orchestration tool ecosystem than what you might think, that they're unable to kill child processes they themselves spawn makes it seem like they have zero clue about what they're doing.

Probably why my impression always end up with "Wow, what a vibe-coded mess" when I look through the source of all these harnesses, they don't seem engineered at all.

by embedding-shape

3/20/2026 at 12:33:56 PM

Have a look at Evan Hahn's murder util: https://codeberg.org/EvanHahn/dotfiles/src/commit/843b9ee13d...

by pluc

3/20/2026 at 5:13:58 PM

Sold on the name alone. It also has the API I never realized I needed

  puts 'usage:'
  puts 'murder 123    # kill by pid'
  puts 'murder ruby   # kill by process name'
  puts 'murder :3000  # kill by port'

by 0cf8612b2e1e

3/20/2026 at 12:58:02 PM

Will check it out

by raskrebs

3/20/2026 at 1:51:19 PM

Mine is called “porthole”

https://github.com/clutchski/dotfiles/blob/main/home/bin/por...

by clutchski

3/20/2026 at 3:33:10 PM

you picked a unique name. There is already a massively popular product called Sonar

by Brainspackle

3/20/2026 at 2:05:25 PM

Any features you are missing or ideas for the use case?

by raskrebs

3/20/2026 at 1:49:47 PM

I am absolutely installing this and starting to use it daily!

For the even less patient there's also this (not mine): https://github.com/jkfran/killport

by pdimitar

3/20/2026 at 2:00:55 PM

Glad to hear! Please join the party and post any issues you have.

by raskrebs

3/20/2026 at 3:51:59 PM

I just have an alias in my .bashrc :)

by RonanSoleste

3/20/2026 at 4:04:28 PM

Try and have a look at the readme, this adds a bit more functionality. Maybe some if it you'll find useful :)

Started with the same, but found my self wanting a bit more, so just built it

by raskrebs

3/20/2026 at 4:50:34 PM

Can it do things that existing tools build into my distro cannot? It looks to me like a convenience tool. Which is fine, but i see no need for it myself

by RonanSoleste

3/20/2026 at 4:53:16 PM

Probably not, that's what makes it so lean (it doesn't really pull in anything).

Although i have a feature branch with a tray app (for macos) that let's you monitor and track any process (will send notifications when one goes up or down). But it's just gimmicks i felt i needed to make life a bit easier when working with compose and across worktrees

by raskrebs

3/20/2026 at 6:25:21 PM

That monitor sounds interesting; I manually set something up in Keyboard Maestro to notify me that something quit and potentially re-launch it.

by Barbing

3/20/2026 at 1:43:43 PM

i have this in my .zshrc which provides same functionality:

  lk() {
    if [ $# -eq 0 ]; then
        local output=$(sudo lsof -iTCP -sTCP:LISTEN -n -P)
    elif [ $# -eq 1 ]; then
        local output=$(sudo lsof -iTCP -sTCP:LISTEN -n -P | grep -i --color=always $1)
    else
        echo "find and kill processes listening on ports. Usage: lk [pattern]"
        return 1
    fi

    if [ -z "$output" ]; then
        echo "No listening processes found."
        return 0
    fi

    # Show header + results
    echo "$(sudo lsof -iTCP -sTCP:LISTEN -n -P | head -1)"
    echo "$output"
    echo ""

    # Extract unique PIDs (skip the header row if no grep was applied)
    local pids=($(echo "$output" | awk '{print $2}' | grep -E '^[0-9]+$' | sort -u))

    if [ ${#pids[@]} -eq 0 ]; then
        echo "No PIDs found."
        return 0
    fi

    echo "PIDs to kill: ${pids[*]}"
    echo -n "Kill these ${#pids[@]} process(es)? [y/N] "
    read -r confirm

    if [[ "$confirm" =~ ^[Yy]$ ]]; then
        for pid in "${pids[@]}"; do
            echo "Killing PID $pid..."
            sudo kill -9 $pid
        done
        echo "Done."
    else
        echo "Aborted."
    fi
  }

by chwzr

3/20/2026 at 2:02:25 PM

I have added quite a lot of functionality beyond listing and killing ports. Please check out the readme, it may convince you to try it out.

by raskrebs

3/20/2026 at 2:08:33 PM

Its funny bc the title suggests a tool for listing and killing

by fionic

3/20/2026 at 3:10:37 PM

HN is a place where people can be expected to go beyond the title (though I like the limited script and am glad it was posted). Misleading titles are not uncommonly flagged and changed, even.

by tomcatfish

3/20/2026 at 2:18:16 PM

True, it was what it started as, but grew as i found my self missing features. Got a few users and now i don't want to update the name. Also easy and quick to write in the terminal

by raskrebs

3/20/2026 at 2:20:59 PM

Why not grep the output to abother tool?

by bartek_gdn

3/20/2026 at 2:07:30 PM

I always find myself going through my zsh history for `lsof`. Will definitely check this out, seems interesting (even though I'm generally reluctant of installing third-party tools for such jobs).

by mfkrause

3/20/2026 at 2:11:17 PM

I get that, i also often install some and forgot about them. But i felt that there was a big gap in managing multiple services running on localhost. It's pretty lightweight if that helps

by raskrebs

3/20/2026 at 5:32:24 PM

Honestly, pretty cool. I was wondering if something like this existed. Right now I have scripts to kill the ports I use consistently to avoid issues when developing. Kudos!

by kohexo

3/20/2026 at 6:44:59 PM

I looked around for a while, couldn't find anything. Someone posted about killport but never stumbled upon it. Has some features that are the same, but not all. From the reaction online people don't seem to know of other solutions like this, or have something they have made them selves in the .zshrc :)

by raskrebs

3/20/2026 at 1:24:09 PM

Sonar as in SonarQube? That's an interesting choice for a name :)

by moezd

3/20/2026 at 1:49:52 PM

How about Sonar as in SOund Navigation And Ranging?

by beart

3/20/2026 at 2:13:31 PM

I think a cli tool that detects objects beneath the surface is a pretty intuitive name, but i was also reluctant in the beginning. But they are pretty keen on always using the qube part, i believe theirs is sonar-qube.

by raskrebs

3/20/2026 at 4:13:09 PM

Christ Almighty I hate our industry practice of binding to some inscrutable port number on localhost. Unix domain sockets aren't that hard! They're secure against all sorts of attacks and more convenient to boot. Instead of connecting to a number, you connect to a file. An ordinary file, with an ordinary name you can mv, chmod, and rm. Boring on a good way.

So why doesn't everyone run local services over Unix sockets?

The only problems: 1) web browsers don't support AF_UNIX URI scheme, and 2) ancient versions of Java don't have built-in APIs for AF_UNIX sockets.

That's it. For these trivial reasons, we've beat our head against arbitrary opaque numbers for decades.

And so, for want of a nail, the Unix was lost.

by quotemstr

3/20/2026 at 4:42:09 PM

Some random daemon binding to 3000 because it's the express default drives me nuts. I either do a Unix socket, a pick any random port if it has to bind on a port.

by 0x457

3/20/2026 at 4:18:48 PM

> So why doesn't everyone run local services over Unix sockets?

> The only problems:

3) 40 years of Windows not supporting UDS.

by formerly_proven

3/20/2026 at 8:13:24 PM

Yeah, that too. Windows supports them nowadays too, just to be clear. I think we're still bottlenecked, right now, on #1 and #2 in the form of Java 8 refusing to die.

by quotemstr

3/20/2026 at 11:22:44 AM

love this, i get tired of spamming lsof -i tcp:xxxx

by Bradd3rs

3/20/2026 at 12:24:43 PM

The README made me realize I just needed a simple `alias local-tcp-listeners='lsof -iTCP -sTCP:LISTEN'` in my `~/.bash_aliases` :)

by Doublon

3/20/2026 at 12:33:42 PM

Same, not sure why a whole cli app is needed.

by deadbabe

3/20/2026 at 12:40:31 PM

Because it gives more context. Quite obvious if you look at the readme...

by paddim8

3/20/2026 at 12:57:32 PM

Developers are nitpicky, atleast i am and i know a lot of others that are as well. So don't underestimate the value of a nice tool with good developer experience, one that's intuitive, clean and easy to use means a lot when juggling so many things during a workday. So having a clean and light implementation to make job even easier is in my opinion worth it (and thus needed) :)

by raskrebs

3/20/2026 at 12:54:39 PM

True, but as i write their are workarounds, the problem is that they are unintuitive, difficult to remember and don't provide all that much usability beyond listing. So these lack useful features like getting process stats, killing ports easily without having to remember the the pid after lsof and so on. I often have to kill multiple process at once after a failed cleanup. If you are into agentic coding, then having your agent create a profile for all the processes it stats, which it can easily kill of when finished is a lot easier for me atleast.

Some features on the way are: next available port; wait (wait for a host to return a successful health check before proceeding - good for migrations etc.). And lots more. It's not just about listing running ports, but a tool for managing them.

But to each their own, that's what's lovely about the many options available. But if you have anything in relation to this you think is neat, feel free to open an issue. It may be able to convince you that a simple alias won't suffice.

by raskrebs

3/20/2026 at 11:43:05 AM

Glad to hear! Have quite a few ideas in mind so keep an eye out for some updates (one of the ideas is an easy update command). There's a couple of open enhancement ideas as well. Feel free to add any or contribute.

by raskrebs

3/20/2026 at 4:47:22 PM

I read the readme. :) Very nice. Thoughtful features. Get this on Homebrew!

by jkestner

3/20/2026 at 4:51:37 PM

I will, but the process is a bit tedious. But will look into it over the weekend

by raskrebs

3/20/2026 at 5:12:09 PM

I recommend just doing a tap in the same repo rather than adding this to homebrew first.

by 0x457

3/20/2026 at 1:14:39 PM

love this, happens too often

by frankdenbow

3/20/2026 at 2:04:35 PM

Exactly, really hates it as well. Please post any issues you may have

by raskrebs

3/20/2026 at 5:31:59 PM

[dead]

by aplomb1026

3/20/2026 at 6:26:40 PM

[dead]

by abitabovebytes

3/20/2026 at 1:38:51 PM

[dead]

by takahitoyoneda

3/20/2026 at 2:04:11 PM

[dead]

by olivercoleai

3/20/2026 at 10:26:30 AM

[dead]

by Servant-of-Inos