DEV Community

Cover image for 🚀 Why Everyone Uses localhost:3000 - The History of Dev Ports (3000, 8000, 8080, 5173)

🚀 Why Everyone Uses localhost:3000 - The History of Dev Ports (3000, 8000, 8080, 5173)

Muhammed Safvan on October 20, 2025

TL;DR: Ever wondered why your dev servers always run on localhost:3000 or localhost:5173? These ports have fascinating histories that t...
Collapse
 
peter profile image
Peter Kim Frank

Thanks for this, have always sort of wondered why it defaulted to these ports and whether there was a deeper story.

Collapse
 
steve-oh profile image
Steve Schafer

I use port numbers of the form XY0Z, where X identifies the specific type of server (web server, event store, Postgres DB, logger, etc.) in project Y, and Z identifies the environment (dev, test, etc.) So 3104 is the web server in the dev environment in project 1, 5306 is the Postgres server in the staging environment in project 3, and so on. Everything is configured via .env files, so I can have multiple projects, each with multiple servers, all running at the same time without interference, and I can readily change environments with a simple script to swap .env files.

This even extends to production, where I use nginx to proxy a URL to the appropriate back end. So, for example, my.domain.com/project1 might be proxied to localhost:3107 behind nginx.

Collapse
 
iamarya profile image
Arya

Interesting. Thanks for sharing.

Collapse
 
shemith_mohanan_6361bb8a2 profile image
shemith mohanan

Loved this write-up! ⚡️ It’s crazy how a few arbitrary defaults (like app.listen(3000)) ended up defining developer culture for decades.
The “Vite = 5173” bit was new to me — that’s a brilliant Easter egg!
I work on an AI-based marketing app called BusinessAdBooster.pro, and even there, dev habits like these sneak into production setups all the time. 😄

Collapse
 
fyodorio profile image
Fyodor

As an Angular developer I'm deeply assaulted not seeing port 4200 history here! 🧐😂 (Wait for the Storybook guys and their 4400 request too 🤣)

Collapse
 
kvetoslavnovak profile image
kvetoslavnovak
Collapse
 
iamarya profile image
Arya

This was very informative and good read.

I am reminded of the art of nudging and sane defaults.

How people prefer to use and stick to defaults to easily cognitive load in their day to day life.

Collapse
 
aoda-zhang profile image
Aoda Zhang

I have no idea why vite was useing 5173 not 80** until you explained this,that is awesome,thx

Collapse
 
chuckmitchell profile image
Charles Mitchell

Port 3000 didn't start with nodejs. Express simply copied Ruby on Rails by using port 3000
So why 3000? - rubyonrails-talk - Ruby on Rails Discussions share.google/ylUvarfxE7lex8A2F

Collapse
 
samkiel profile image
ѕαмкιєℓ.∂єν

This is cool. Thanks 😊

Server running on Port {port}
Enter fullscreen mode Exit fullscreen mode
Collapse
 
drakerp2 profile image
drakerp2

There is also a public registry where companies or software can "claim" ports. If you go high up into these you will find valleys of ports that are completely open, very useful if using ports as part of local code for end users (first example that comes to mind is python multiprocessing shared memory can be mounted to a port to be accessible by any other independent python script)

Collapse
 
zupo profile image
Neyts Zupan

The history is interesting, but I think most developers just pick whatever high port is free. Standardizing on 3000 or 8000 isn’t sacred and switching to random ports often avoids conflicts just as well.

Collapse
 
justindthomas profile image
Justin Thomas

I would have assumed Ruby on Rails was the source of the port 3000 convention. I feel like that was the first time I remember seeing its use in the wild back in the late aughts.

Collapse
 
itamartati profile image
Itamar Tati

Awesome Article

Collapse
 
laikokwui profile image
Kok Wui Lai

i always use default 4200 and 8100

Collapse
 
tmccombs profile image
Thayne McCombs

I suspect 8000 is also related to port 80 being used for http. Take 80, add a couple of zeros to get something big enough not to be in the privileged range, and you get 8000.

Collapse
 
a-k-0047 profile image
ak0047

Thanks for sharing!
I’ll try using a port number I haven’t used before.

Collapse
 
kurealnum profile image
Oscar

pretty neat, cool easter eggs!

Collapse
 
ayomide661 profile image
Abdulmumeen abdulkareem

Now I understand it better 😮‍💨

Collapse
 
devtanmay profile image
Tanmay Gupta

Great read!

Collapse
 
samuel_leonardo_37aff38b4 profile image
Samuel Leonardo

Que bueno y chevre, estoy desarrollando un lenguaje de programación llamado MAWA, creado por mi.

How nice and cool, I'm developing a programming language called MAWA, created by me.

Collapse
 
somanath444 profile image
Somanath

Think it as a building and the rooms inside the building is a great analogy that made me understand it in easier way.

Collapse
 
linjunjie525 profile image
Lin JunJie

Loved this deep dive!
Never realized how much history those simple port numbers carry
5173 being “VITE” is just genius

Collapse
 
coffeejuseyo profile image
coffeejuseyo

Cool. Thanks for sharing

Collapse
 
ycmjason profile image
YCM Jason • Edited

I always wondered what 5173 refers to! I knew there must be an easter egg! Thank you!!

Collapse
 
ijay profile image
Ijay

Thanks for breaking it down.

Collapse
 
fengmk2 profile image
fengmk2

Tell a cold joke: If you are a fan of Stephen Chow movies, then 3000 naturally brings to mind the classic line: "夺命 3000" youtube.com/watch?v=elc3FdKxaOk

Collapse
 
masibaga profile image
Masimo Bagano

Very interesting read, thank you.

But VI would be six.