# apple/pkl

A configuration as code language with rich validation and tooling.

Repository: https://github.com/apple/pkl
Canonical: https://ross.abutalabs.com/products/pkl
Homepage: https://pkl-lang.org
Language: Java
License: Apache-2.0
License Family: permissive
Topics: pkl, java, kotlin, config, configuration, data, functional, json, language, object-oriented, programming-language, properties, propertylist, validation, xml, yaml
Last push: 2026-08-26T22:45:19+00:00

## Health v2 (maintenance only)
Score: 87/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 82, longevity 68
- inputs: {"age_days": 957, "days_push": 7, "days_rel": 41, "gap_med": 34.0, "n_releases_24m": 15}
- flags: no_readme
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 11497, forks 399 (observed 2026-08-28T04:10:48.363763+00:00)

## What it is
Pkl is a configuration-as-code language from Apple with rich validation, templating, and tooling for defining programmable, scalable, and safe configuration. It ships a CLI with a REPL, generates JSON, YAML, property lists, and static config formats, and offers bindings for Java, Kotlin, Swift, and Go.

## Use cases
- generate json yaml plist from a single config source
- validate application configuration with type checks
- manage kubernetes configuration as typed templates
- embed a config language into jvm or swift applications
- replace jsonnet or yaml for complex config
- generate typed config classes for java kotlin swift go

## When to choose
- you need programmable, validated configuration beyond what yaml or toml offers
- you must emit multiple config formats from one source of truth
- you want type-safe config bindings for jvm, swift, or go apps
- you manage kubernetes or CI configs that benefit from templates and validation

## When to avoid
- your configuration is simple and flat where yaml or env files suffice
- your team cannot adopt a new language for config
- you need a widely adopted standard with a large ecosystem
- you only need runtime config without code generation or validation

## Facets
- artifact type: cli-tool
- maturity: active
- function: configuration-management, serialization, form-handling, cli, programming-language
- domain: developer-tools, programming-languages
- platform: windows, jvm, cli, cross-platform
- tags: config-as-code, configuration-language, json-yaml-plist, kubernetes-config, spring-boot, code-generation, type-safe-config, configuration, devops, macos, linux

## Member repositories
- apple/pkl (main) score 87

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:48.363763+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:15:32.922451+00:00, confidence not recorded.
  - homepage: https://pkl-lang.org (fetched 2026-08-29T08:14:09.907131+00:00, sha 20c0d73e7211)
  - site_page: https://pkl-lang.org/package-docs/pkl/current/index.html (fetched 2026-08-29T08:14:09.917991+00:00, sha f2d2b504660c)
  - site_page: https://pkl-lang.org/package-docs (fetched 2026-08-29T08:14:09.919649+00:00, sha 2e2465fd6fa2)
  - site_page: https://pkl-lang.org/main/current/integrations.html (fetched 2026-08-29T08:14:09.916325+00:00, sha c3b7f70766bf)
  - site_page: https://pkl-lang.org/main/current/pkl-cli/index.html (fetched 2026-08-29T08:14:09.921386+00:00, sha 21e865b9d7b1)
- Data as of 2026-08-30T08:39:29.467469+00:00.