I built https://RTCode.io to escape their sluggish hell! CodePen has no place in today's world.

- everything is local until you deploy

- with first-class support for

  - connect your AI to playground

    - version-controlled deployments

    - full playground control

      - output viewport size, zoom, color scheme control

      - output eval for AI for immediate tests and feedback

      - output live capture and image-cropped element/region pins

    - output live stream picture-in-picture to watch your agents work

  - state preserving 2-way IO sync

  - multi-level open shadow root IO sync

  - service/edge workers in the playground (develop full-stack apps in one place)
    
    - import ESMs or WASMs by URL (yes in workers!)

    - examples: https://new.rt.ht

    - example: https://post.rt.ht

    - example: https://kv.rt.ht/fs

- enterprise-class global network: https://RTEdge.net

  - built-in auth for deployments: https://elefunc.com/#auth

Too many features to list them all here! A lot of these features are unique and will never exist in other places, because everyone is busy chasing the next release of React or other cancerous bullshit instead. I only use web standard/platform APIs and drive things up to their simplest forms! Auth is just 4 letters added to location.pathname for example!

These days, I don't even code in https://RTCode.io myself, I share the playground with Codex/Claude and let them build me my dreams in the form of full-stack apps! I PiP-watch them live on the side as they work and deploy!

For more info: https://elefunc.com/#code

There’s a detailed discussion of the same issue here https://www.reddit.com/r/webdev/comments/1rj1oac/i_planted_f...

For basic previewing I like to use https://htmledit.squarefree.com which has been online for years and does it all client side.

i made my own html playground that is browser only and shares preview via url hash because of these useless shenanigans of codepen, its not as featureful but i mostly use it for sharing single page html files

https://easyanalytica.com/tools/html-playground/

You're gonna be shocked how many input fields do this for various UX features :)

because this is how autocomplete logic works i guess? Frontend cannot guess language and completions for you

Sent to them to render the preview pane. Same as pasting secrets anywhere on a browser.

Wait until you find out copying content on a computer might sent it over Wi-Fi/Bluetooth for sharing on other devices.

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