Apple Pkl

A programming language for creating and validating configuration files, then exporting them to JSON, YAML, or code.

pkl-lang.org

Verified API available

Quick facts
What is it	A programming language for creating and validating configuration files, then exporting them to JSON, YAML, or code.
Pricing	Unknown
Platform	API
API	Yes
Best for	defining application settings and environment variables, generating deployment manifests for Kubernetes or other systems
Domain registered	2023

Data updated Aug. 1, 2026

What does Apple Pkl do?

Pkl is a programming language designed specifically for writing configuration files. Instead of manually editing static JSON, YAML, or XML files, you write code in Pkl. This code can define types, set validation rules, and reuse values. Once defined, the Pkl code is then compiled and exported into the standard configuration format your application needs, such as JSON, YAML, Property Lists (plist), or .properties files. This turns a typically error-prone manual process into a programmable and repeatable one.

What makes Pkl stand out is its integration with application code. It doesn't just generate static config files; it can also generate type-safe classes for Java, Kotlin, Swift, and Go. This means your application can load a Pkl configuration at runtime and work with it as a native object, complete with validation and autocompletion. The language includes a rich type system for catching errors early, and it offers excellent IDE support with plugins for IntelliJ, VS Code, and Neovim.

Pkl is built for developers and platform engineers who manage complex application configurations. It is extremely useful for teams that need to maintain multiple environment configs (dev, staging, production) with subtle differences, or for anyone tired of hunting down typos in YAML files. A common use case is defining a single, validated source of truth for an app's settings and then generating the necessary config files and code for different parts of the stack from that one Pkl module.

Development — Other

#code generation#developer tools

Key features

What makes it stand out

Generates multiple output formats (JSON, YAML, XML, Properties) from a single Pkl source

Produces type-safe code for Java, Kotlin, Swift, and Go applications

Provides rich IDE support with plugins for IntelliJ, VS Code, and Neovim

Includes a type and validation system to catch configuration errors before deployment

Allows for programmable configuration with reusable code and logic

Who is Apple Pkl for?

Who benefits most from this tool

defining application settings and environment variables

generating deployment manifests for Kubernetes or other systems

managing shared configuration across multiple services or formats

Trust & presence

Domain Domain registered 2023

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