Frequently Asked Questions

What's is a service where you can write JavaScript, HTML5, CSS on your browser, and share it.
Experiencing is better than reading, so sign in (it's super easy) and try it out!

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How to get the latest information about

You can get the lastest news about on Twitter and Facebook.

Official Twitter Account:

Official Facebook Page: Facebook Page

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How should I do if wanting to a certain JavaScript library?

Click '+ Add Library' button on the code editing page.
'Major Libraries' are major libraries that are frequently used.
'Your Recent Code' shows some of the codes you've posted recently.
'Input URL' is a place to specify any code in to load as a library.
Your own library can be loaded by posting it to first and then specifying a path.

You can find all the libraries that is providing in the URL shown below.

And if you want to add or update any library, please feel free to contact us.

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About the code compilation feature also has implemented the feature of compiling codes.
Languages listed below can be used.

  • JSX: can be compiled into JavaScript.
  • CoffeeScript: can be compiled into JavaScript.
  • TypeScript: can be compiled into JavaScript.
  • SCSS: can be compiled into CSS.
  • Compass: can be compiled into CSS.
  • LESS: can be compiled into CSS.

You can use the compilation feature in the way shown below.

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About Markdown feature

In, you can use Markdown syntax in README tab, as shown below.

  • Go to the README tab in editor
  • Select "Markdown" in the left format selector.
  • If Preview is clicked, a preview of the written article will show up.

You can check the Markdown Syntax here:

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About Emmet feature

You can use Emmet when you edit HTML in editor.

For example, in HTML tab, if you input div#page>div.logo+ul#navigation>li*5>a and then press Tab key, the code will be automatically converted into codes shown below.

Also in CSS tab, if you input w200+h100+m0-a and press Tab key, it will be automatically converted to CSS code as below.

You can check for more information by clicking the Emmet Documentation link in the top-right corner.

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How to apply a version control system to my code?

You can activate the version control feature by uploading code to Gist.
The code will be committed to Gist every time you save.

You can upload code to Gist as shown below.

  • After finishing editing the code, press the triangle on the right of the Save button.
  • Select Save to Gist from the dropdown menu

※ For user that hasn't connected GitHub, it's necessary to connect to GitHub only for the first time.
※ After connecting with GitHub, please don't forget to select Save toGist again.

When uploaded,you can select version from the dropdown menu on the left of the Save button.

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About the additional features of our editor

Besides syntax highlight, code compilation, auto indent, editor also supports convenient features like fold/expand and search/replace.

  • Fold/Expand

Pressing Ctrl-Q, or clicking the line number will fold the code block.
And clicking once more will expand it.

  • Search/Replace

You can perform searching or replacing by keyboard shortcuts.

Search: Ctrl-F / ⌘F
Find the next match: Ctrl-G / ⌘G
Find the previous match: Shift-Ctrl-G / ⇧⌘G

Replace: Shift-Ctrl-F / ⌥⌘F
Replace all: Shift-Ctrl-R / ⇧⌥⌘F

What's more, you can also use RegExp when you search/replace.

  • Switching Tabs

You can also use shortcut key to switch tab.

READMEタブ: Ctrl + 1 / ⌘1
JavaScript Tab: Ctrl + 2 / ⌘2
HTML Tab: Ctrl + 3 / ⌘3
CSS Tab: Ctrl + 4 / ⌘4
File Tab: Ctrl + 5 / ⌘5
Properties Tab: Ctrl + 0 / ⌘0

  • Other

You can also save or reload preview by shortcut key.

Save: Ctrl + S / ⌘S
Reload: Ctrl + R / ⌘R

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Do you host the code? Can I load it from my site?

Yes, we host your JavaScript and CSS.

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How to set my code not visible to the public?

You can make code only visible to yourself as shown below.

  • Go to the edit page (editor) of the code.
  • Click the Properties button on the right.
  • Turn on Private option in the Properties tab, and press Save.

By then, the code is only visible to your self.

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I cannot delete my code. Why?

That's because your code is being used as a library by someone else.
Codes that are referred to as a library cannot be deleted.
All the codes on can be used as a library by specifying the code's path from "+Add Library" on the code editing page.

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How to ask a question in Discussion?

You can ask a question as shown below.

  • Press "Post a question" button in Discussions.
  • Fill in the Title, Description, etc.
  • If necessary, you can fill in Tag or even attach your code.
  • If "Create" button is pressed, a new code will be created, and automatically be attached to the question.
  • After filling all the things you think necessary, press "Add Question" button to post.

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How to answer a question in Discussion?

You can answer a question as shown below.

  • First, go to the question that you'd like to answer in Discussion.
  • When you answer the question, you can fork the original code in the form, or create a new one.
  • And please remember to fill in Description.
  • After filling all the things you nedd, press "Add Answer" button to answer the question.

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About capture images

Taking a capture image of your JavaScript, HTML5, CSS will be done automatically.
If your capture shows 'Now Capturing', it's been queued up, and waiting for capture.
Wait a moment till it get's captured.
To customize the capture image, you can upload any picture you want in the properties tab.
Any JPG, PNG, GIF picture in size of 465px * 465px can be used.

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About images

You can upload images on
There's no limitation for the format.
However, for each code, you can only upload files in total not exceeding 1MB.

You can use your images as shown below.

  • Click Files tab in the editor.
  • Drag the image you'd like to use to the target area, and the image will be uplaoded.
  • If upload finish, a thumbnail and URL of the image will show up.
  • Now you can paste the URL to your code to use the image.

Also, you can choose to convert the image to dataURI, which can be directly used in your code. You can refer to the code below for the convertion.

DATA URI Playground2 (DATA-URI Converter for

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About uploading

You can upload any file in
There's no limitation for the filetypes.
But the size of the attached files should be below 1MB in all.

You can upload files as shown below.

  • Go the Files tab of the editor
  • Drag and drop the file you'd like to use into the sqaure. File will start uploading.
  • Once upload completes, a URL will show up.
  • You can use the URL anywhere in your code.

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About license

The code your wrote in belongs to you.

You're free to license your code.
But code sharing is a prerequisite for,
so when you post any code, we assume you agreed to allow the following, even if you choose 'All rights reserved'.
* service to redistribute your code and binary through service
* other users to use's core feature: 'fork', to modify and merge your code
see Terms of Use for more information.

You can set a different license for each of your code,
and also set a default license for your future codes.

To set a license for your code, choose one from below while code editing:
* All Rights Reserved
* MIT License
* GPLv3 License
* other license, see code comments
You declare the license by showing a link to the full license text near the code (this is done by service).
If you choose the 4th option, show a link or all of the full license text in code comments by yourself.

When you fork other users code, the license of the new code will be the forked-parent-code's license.
You can't change your code's license after fork.
We think it's important not to violate somebody's license easily, than have convenience of changing license easily.

If your code loads GPLv3 code as libraries, your code license will be automatically changed to GPLv3 and won't be able to change it to other licenses

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About the usage of API provides API that can gather info of users and codes.
To check the usage of API, please see our docs.

→ API's documentation:

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About assets

We've collected our logos and assets such as SVG Girls in Assets page.
You can use them for free

→Assets Page:

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How to delete my account?

You can delete your account in your settings page.


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Looking for advertisements, and partners!
Do you have a product targeting users? or have any job offering for JavaScript, HTML5, CSS developers?
or want to use's Engine? or anything else.
Also waiting for any feature request.
Contact us at:

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Special Thanks!

thanks to jslint, our JavaScript lint program uses jslint.
thanks to codemirror, our JavaScript editor heavily utilizes codemirror.
thanks to ZenCoding, our editor supports ZenCoding shortcuts.
thanks to PhantomJS, our screenshot feature utilizes PhantomJS.

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