DuperThe format that's super!

A human-friendly extension of JSON with quality-of-life improvements, extra types, and semantic identifiers.

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🎨

Human-friendly

Quotes optional for keys, trailing commas, comments, and clean syntax.

🔧

Rich types

Tuples, bytes, raw strings, identifiers, and more beyond basic JSON.

🔄

JSON-compatible

Every valid JSON file is automatically valid Duper.

📝

Self-documenting

Identifiers provide type hints, readability, and validation guidance.

Why Duper?

Duper excels in a variety of use cases:

Configuration files: Duper's explicit types and identifiers serve as helpful guides when users need to modify values.
REST APIs: Self-documenting identifiers make Duper feel natural in API payloads and responses.
Data interchange: With support for bytes, raw data, minimal syntax, and JSON compatibility, Duper is ideal for data exchange between systems.

Full example

duper

UserProfile({
  id: Uuid("f111c275-b4ce-4392-8e5b-19067ce39b53"),
  username: "EpicEric",
  email: EmailAddress("eric@duper.dev.br"),
  settings: {
    "dark mode": true,
    language: LanguageAlpha2("en"),
  },
  avatar: Png(b"\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR"),
  bio: r#"Hello! I'm a super "duper" user!"#,
  last_logins: [
    (IPv4Address("192.168.1.100"), DateTime("2024-03-20T14:30:00Z")),
  ],
})

Comparison

Feature	JSON	JSON5	TOML	YAML	Duper
Comments	❌	✅	✅	✅	✅
Trailing commas	❌	✅	✅	✅	✅
Unquoted keys	❌	✅	✅	✅	✅
Unambiguous	✅	✅	⚠️	❌	✅
Identifiers	❌	❌	❌	❌	✅
Tuples and bytes	❌	❌	❌	❌	✅
Raw strings	❌	❌	✅	⚠️	✅
Simplicity	✅	✅	✅	❌	⚠️
Popularity	✅	❌	✅	✅	❌