# carvel-dev/ytt

YAML templating tool that works on YAML structure instead of text

Repository: https://github.com/carvel-dev/ytt
Canonical: https://ross.abutalabs.com/products/ytt
Homepage: https://carvel.dev/ytt
Language: Go
License: Apache-2.0
License Family: permissive
Topics: cli, go, yaml, devops, templating, kubernetes, yaml-processor, yml, k8s, data-structures, configuration, carvel
Last push: 2026-08-25T02:20:30+00:00

## Health v2 (maintenance only)
Score: 95/100 (v2, computed 2026-09-03T02:39:23.370411+00:00)
- activity 99, release rhythm 86, longevity 100
- inputs: {"age_days": 2743, "days_push": 9, "days_rel": 19, "gap_med": 39.5, "n_releases_24m": 15}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1874, forks 167 (observed 2026-08-28T04:05:47.400542+00:00)

## What it is
ytt is a command-line YAML templating and patching tool that operates on YAML structure rather than text, using annotations and a sandboxed Starlark language. It supports data values, reusable templates, and overlays for customizing configuration like Kubernetes manifests, Concourse pipelines, and Docker Compose files.

## Use cases
- template kubernetes manifests with environment-specific values
- patch third-party yaml files with overlays
- avoid yaml quoting and indentation issues in templating
- externalize configuration values from yaml files
- generate docker compose or github actions workflow files from templates
- modularize large piles of yaml configuration

## When to choose
- you need structure-aware yaml templating instead of text substitution
- you manage complex kubernetes configuration across multiple environments
- you want deterministic, sandboxed template execution
- you need to patch yaml you don't own without editing it directly

## When to avoid
- you only need simple key-value substitution in non-YAML files
- your team prefers plain helm or kustomize workflows
- you need a general-purpose text templating engine like jinja

## Facets
- artifact type: cli-tool
- maturity: active
- function: templating, configuration-management, cli, developer-tools
- domain: developer-tools, infrastructure-as-code
- platform: cli, windows, go
- tags: yaml, kubernetes, starlark, overlays, carvel, configuration-as-code, devops, automation, linux, macos

## Member repositories
- carvel-dev/ytt (main) score 95

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:47.400542+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 2026-08-30T03:14:47.730755+00:00, confidence not recorded.
  - readme: https://github.com/carvel-dev/ytt (fetched 2026-08-28T04:05:47.400542+00:00, sha e57c962585d6)
  - homepage: https://carvel.dev/ytt (fetched 2026-08-29T10:53:42.661395+00:00, sha bc43695b793c)
  - site_page: https://carvel.dev/shared/docs/latest (fetched 2026-08-29T10:53:42.670628+00:00, sha 8e30760f8ffc)
  - site_page: https://carvel.dev/ytt/docs/v0.52.x (fetched 2026-08-29T10:53:42.672607+00:00, sha 2d32c94cdf2f)
  - site_page: https://carvel.dev/ytt/docs/latest/install (fetched 2026-08-29T10:53:42.674620+00:00, sha ba7c96528609)
- Data as of 2026-08-30T08:39:29.467469+00:00.