Build HTML emails, but without the torture

Crafting HTML emails has always been a pain—inline styles, inconsistent rendering across email clients, and a sea of outdated quirks to navigate. ELOS changes that.

ELOS is a declarative, developer-friendly language designed specifically for building responsive, accessible, and beautifully branded HTML emails. Forget about manually wrestling with tables and obscure CSS hacks—ELOS abstracts the complexities, letting you focus on design and content while ensuring rock-solid email compatibility.

With ELOS, you get:

✅ Simplified Syntax – Write structured, readable code that compiles into bulletproof HTML. ✅ Smart Defaults – No more worrying about missing styles or broken layouts. ✅ Reusable Components – Build once, reuse everywhere. ✅ Responsive by Default – Emails that look great on any device, without extra hassle.

Say goodbye to email development torture and hello to ELOS.

Getting started

Option 1) Install the language

npm install elos

elos <input-file> [output-file]

Option 2) Use with a build tool

• Use with Vite: vite-plugin-elos

Contribution

See Contributing Guide.

License

MIT

Roadmap v1

• Error improvements:
  • Throw an Error on accessing undefined variable
• Primitives:
  • Use Expressions where applicable
    • TODO:
      • ~~DefNode~~
      • ~~TxtNode~~
      • ~~ImgNode~~
  • ~~Variables~~
  • ~~String~~
  • ~~Number~~
  • ~~Colors~~
• ~~Single-line comments~~
• Improved (cleanup) styling system
  • Basic inheritance (extend from node style): selector "group.intro" extends from "group"
• Syntax improvements (consistency):
  • ~~Every node that has a block body should use { } (e.g. cols)~~
• 100% test coverage

Roadmap v2

• Full templating support:
  • Conditionals
  • Loops (for, forEach)
  • Advanced primitives: lists, maps

Getting started

Language design example

def $preview "Welcome to ELOS!"
def $width 750
def $hgap 25
def $vgap 25

style group {
    padding 25
}

style btn {
    size 14
    bgcolor "#f14000"
}

style txt {
    size 14
    color "#333333"
}

style .footer {
    bgcolor "#cccccc"
}

style .cta {
    padding 50
    bgcolor "#f10000"
}

style .h {
    color "red"
    size 18
    transform "uppercase"
}

style .hh {
    color "blue"
    size 16
}

body {
    space
    img "https://dummyimage.com/600x200/000/fff" -> "https://www.google.be"
    group {
        txt.h "Welcome to ELOS"
        space
        cols {
            col {
                img "https://dummyimage.com/600x400/000/fff"
            }
            col {
                img "https://dummyimage.com/600x400/000/fff"
            }
            col {
                img "https://dummyimage.com/600x400/000/fff"
            }
        }
    }
    group.cta {
        btn "Discover more" -> "https://github.com/elos-lang/"
    }
    group {
        cols {
            col {
                txt "Welcome to ELOS"
                img "https://dummyimage.com/600x400/000/fff"
            }
            col {
                txt "Welcome to ELOS"
                img "https://dummyimage.com/600x400/000/fff"
            }
        }
    }
    line
    group.footer {
        cols {
            col {
                txt.hh "Welcome to ELOS"
                img "https://dummyimage.com/600x400/000/fff"
            }
            col {
                txt.hh "Welcome to ELOS"
                img "https://dummyimage.com/600x400/000/fff"
            }
        }
    }
    space
}