The chart is a set of configuration files which describe an application. Chart files reside in the .helm directory under the root directory of the project:

.helm/
  templates/
    <name>.yaml
    <name>.tpl
    <some_dir>/
      <name>.yaml
      <name>.tpl
  charts/
  secret/
  values.yaml
  secret-values.yaml

werf chart has an optional .helm/Chart.yaml description file, which is fully compatible with helms Chart.yaml` and could contain following content:

apiVersion: v2
name: mychart
version: 1.0.0
dependencies:
 - name: redis
   version: "12.7.4"
   repository: "https://charts.bitnami.com/bitnami" 

By default, werf will use project name from the werf.yaml as a chart name, and default version is always 1.0.0. You can redefine this by placing own .helm/Chart.yaml with overrides for chart name or version:

name: mychart
version: 2.4.6

.helm/Chart.yaml is also needed to define chart dependencies.