What is JSON to CUE Constraint Generator?
CUE is an open-source data constraint language designed for configuration, validation, and data definition. It combines types, values, and constraints into a single unified language, making it ideal for defining and validating configuration files, API schemas, and data pipelines. This tool generates CUE constraint definitions from your JSON data with automatic type inference.
How to Use
- Configure options: toggle closed structs, package declaration, and value constraints
- Paste your JSON data into the input area
- Click "Generate CUE" to create the constraint definitions
- Copy the output and save it as a .cue file in your project
Why Use This Tool?
Tips & Best Practices
- Use realistic sample data — type inference depends on actual values
- Enable "Closed structs" to prevent additional fields (strict validation)
- Enable "Include value constraints" to add range limits for numbers and regex patterns for strings
- Fields with null values are automatically marked as optional in CUE
Frequently Asked Questions
What is CUE?
CUE is an open-source data constraint language designed for configuration, validation, and data definition. It combines types, values, and constraints into a single unified language, making it ideal for defining and validating configuration files, API schemas, and data pipelines.
How are JSON types mapped to CUE types?
JSON strings → string, integers → int, floats → number, booleans → bool, null → optional field, arrays → [...Type], nested objects → nested CUE struct definitions.
What are closed vs open structs?
Closed structs (the default) do not allow additional fields beyond those defined, providing strict validation. Open structs (using the ... marker) allow extra fields, which is useful for extensible configurations.
Is my data sent to a server?
No, all processing happens entirely in your browser. Your JSON data never leaves your device.