A list of programming playgrounds

I really like using (and making!) programming playgrounds, and I got thinking the other day about how I didn’t have a great list of playgrounds to refer to. So I asked on Mastodon for links to cool playgrounds.

Here’s what I came up with. I’d love to know what I missed.

• Compilers: godbolt compiler explorer by Matt Godbolt
• Shaders: shadertoy by Inigo Quilez and Pol Jeremias
• Arduino / IoT: wokwi from CodeMagic
• CSS/HTML/JS: CodePen by Chris Coyier, Alex Vasquez, and team
• CSS/HTML/JS: JSFiddle by Oskar Krawczyk and Piotr Zalewa
• CSS/HTML/JS: flems by Rasmus Porsager (saves all state in the URL)

• regular expressions:

  • for many languages: regex101 by Firas Dib
  • for Ruby: Rubular by Michael Lovitt
  • for JS/PCRE: regexr by gskinner
  • for Python: Pythex by Gabriel Rodríguez
• DNS: Mess With DNS by Julia Evans and Marie Flanagan
• DNS: DNS lookup tool by Julia Evans
• nginx: nginx playground by Julia Evans
• varnish: fastly fiddle from fastly
• SQLite: sqlime by Anton Zhiyanov (lets you load arbitrary SQLite databases)
• SQL: DB fiddle from Status200
• SQL: sql playground by Julia Evans
• Postgres: postgres playground from Crunchydata (runs postgres in the browser!)
• Git: oh my git by blinry and bleeptrack
• .NET bytecode: SharpLab by Andrey Shchekin
• Python bytecode: dis this by Pamela Fox

data formats

• Floating point: Float Exposed by Bartosz Ciechanowski
• Unicode: Unicode analyzer from fontspace
• Unicode: What unicode character is this? from babelstone
• ASN.1 certificates: ASN.1 JavaScript debugger by Lapo Luchini
• SVG: sssvg (interactive SVG reference) from fffuel (lots of other cool tools there)
• CBOR: CBOR playground
• JSON: JSON editor online by Jos de Jong
• cron: crontab guru from cronitor

programming languages

• official playgrounds:

• unofficial playgrounds:

  • PHP: 3v4l by Sjon Hortensius
  • Python/JS/C/C++/Java: Python Tutor by Philip Guo
  • Javascript: JS Console by @rem
  • many languages: riju by Radon Rosborough
  • many languages: replit
  • others: jqplay for jq, tryapl for APL