# How to start development server

**URL:** <https://discourse.processing.org/t/how-to-start-development-server/47618>\
**Category:** Development\
**Tags:** contributions\
**Created:** [December 15, 2025, 8:38am UTC](https://discourse.processing.org/t/how-to-start-development-server/47618 "2025-12-15T08:38:24Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![thejon\_07](https://avatars.discourse-cdn.com/v4/letter/t/9e8a1a/32.png) [@thejon\_07](https://discourse.processing.org/u/thejon_07)\
**Post date:** [December 15, 2025, 8:38am UTC](https://discourse.processing.org/t/how-to-start-development-server/47618/1 "2025-12-15T08:38:24Z")

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Hi everyone,  
I am new to the Processing Foundation. I am facing issues while starting the development server for the p5.js repository. Can anyone help me with this? Thank you.

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**Author:** ![glv](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/glv/32/18785_2.png) [@glv](https://discourse.processing.org/u/glv)\
**Post date:** [December 15, 2025, 10:41pm UTC](https://discourse.processing.org/t/how-to-start-development-server/47618/2 "2025-12-15T22:41:53Z")

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Hello @thejon_07 ,

Are you referring to this?

> <https://github.com/processing/p5.js-website/blob/main/docs/technical_overview.md>

`:)`

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<div class="post-metadata">

**Author:** ![thejon\_07](https://avatars.discourse-cdn.com/v4/letter/t/9e8a1a/32.png) [@thejon\_07](https://discourse.processing.org/u/thejon_07)\
**Post date:** [December 16, 2025, 2:55pm UTC](https://discourse.processing.org/t/how-to-start-development-server/47618/3 "2025-12-16T14:55:12Z")

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@glv no just p5.js repository.;;;;;;

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**Author:** ![glv](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/glv/32/18785_2.png) [@glv](https://discourse.processing.org/u/glv)\
**Post date:** [December 17, 2025, 1:12am UTC](https://discourse.processing.org/t/how-to-start-development-server/47618/4 "2025-12-17T01:12:12Z")

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> [@thejon\_07](#):
>
> I am facing issues while starting the development server for the p5.js repository.

Hello @thejon_07 ,

What is your point of entry for starting this?  
Link?  
What issues?

I managed to get this to work on Windows 10 following this:

> **[Quick Get Started For Developers - Contributor Guidelines](https://p5js.org/contribute/contributor_guidelines/#quick-get-started-for-developers)**
>
> Welcome to the contributor guidelines! This document is for new contributors looking to contribute code to p5.js, contributors looking to refresh their memories on some technical steps, or just about anything else to do with code contributions to...

Additional notes:

- **Installed**  **grunt** :  
`npm install -g grunt-cli`
- **Start the development server** :  
`npm run dev`.
- **Open a sketch** in Google Chrome: `http://127.0.0.1:9001/sketches/sketch_1_0_0/index.html`.
- **I did not go past building.**

I was able to change _ **p5.js** _ source code to add a red stroke to `circle()`, build and then see the changes reflected in my sketch.

Modified _ **2d\_primitives.js** _ in _ **p5.js** _ source code:

```auto
p5.prototype.circle = function(...args) {
  p5._validateParameters('circle', args);
  const argss = args.slice( 0, 2);
  argss.push(args[2], args[2]);
  this.stroke(255, 0, 0); // Add red border to circle
  return this._renderEllipse(...argss);
};

```

 ![image](https://canada1.discourse-cdn.com/flex036/uploads/processingfoundation1/original/3X/c/b/cbd134055faf9c60b1d1c9530f99fb89688024f5.png)

_I am also new to setting up this development environment but do have experience that helped me along._

\*\*\* **UPDATE** \*\*\*

Additional reference:

> <https://github.com/processing/p5.js/blob/main/contributor_docs/contributor_guidelines.md#quick-get-started-for-developers>

The _Related Topics_ at the bottom of a topic may also be helpful. \< A reminder for me as well!

`:)`

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<div class="post-metadata">

**Author:** ![glv](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/glv/32/18785_2.png) [@glv](https://discourse.processing.org/u/glv)\
**Post date:** [December 17, 2025, 7:54pm UTC](https://discourse.processing.org/t/how-to-start-development-server/47618/5 "2025-12-17T19:54:03Z")

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Season’s Greetings!

> [@thejon\_07](#):
>
> @glv no just p5.js repository.;;;;;;

_[How to Fix a Jammed or Stuck Keyboard Key: 5 Easy Ways](https://www.wikihow.com/Fix-a-Jammed-Keyboard-Key)_

`:)`

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**Author:** ![MilaVibes](https://avatars.discourse-cdn.com/v4/letter/m/7bcc69/32.png) [@MilaVibes](https://discourse.processing.org/u/MilaVibes)\
**Post date:** [January 3, 2026, 2:52pm UTC](https://discourse.processing.org/t/how-to-start-development-server/47618/6 "2026-01-03T14:52:56Z")

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Hey @thejon_07, have you made sure all the necessary dependencies are installed before starting the dev server? I had similar issues at first, and installing tools like grunt and npm helped resolve most of the problems. That might help you too! Good luck!

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<div class="post-metadata">

**Author:** ![thejon\_07](https://avatars.discourse-cdn.com/v4/letter/t/9e8a1a/32.png) [@thejon\_07](https://discourse.processing.org/u/thejon_07)\
**Post date:** [January 19, 2026, 6:08pm UTC](https://discourse.processing.org/t/how-to-start-development-server/47618/7 "2026-01-19T18:08:46Z")

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thanks @MilaVibes for your assist