How does it flatten nested YAML?

Dot path becomes underscore-separated UPPER_CASE: `db.host` → `DB_HOST`. Arrays use numeric suffixes (`ITEMS_0`, `ITEMS_1`).

What about complex values?

Objects and arrays can't be .env-native. They become JSON-stringified strings: `SERVERS='["a.com","b.com"]'`.

Stripped — .env supports comments but YAML-to-.env focuses on the data. Add top-level `# generated from config.yaml` manually if you want provenance.

Pair with env-to-yaml. The round-trip is lossless for simple data; complex values that got JSON-encoded need the inverse parsing.

A worked example, rendered from real sample data. Sign in to run the tool on your own input.

Input

app:
  name: myapp
  port: 3000
database:
  host: localhost
  user: postgres

Output

APP_NAME=myapp
APP_PORT=3000
DATABASE_HOST=localhost
DATABASE_USER=postgres

Flatten a YAML file to KEY=value lines. Part of the DevTools Surf developer suite. Browse more tools in the Converters collection.

YAML was first proposed in 2001 by Clark Evans, and its name originally stood for 'Yet Another Markup Language' before being changed to 'YAML Ain't Markup Language.'
The .env file convention was popularized by the Twelve-Factor App methodology published by Heroku in 2011, which advocates storing config in environment variables.
Docker Compose introduced YAML-based service configuration in 2014, making YAML-to-env conversion a common DevOps task.

How does it flatten nested YAML?: Dot path becomes underscore-separated UPPER_CASE: `db.host` → `DB_HOST`. Arrays use numeric suffixes (`ITEMS_0`, `ITEMS_1`).
What about complex values?: Objects and arrays can't be .env-native. They become JSON-stringified strings: `SERVERS='["a.com","b.com"]'`.
Are comments kept?: Stripped — .env supports comments but YAML-to-.env focuses on the data. Add top-level `# generated from config.yaml` manually if you want provenance.
Round-trip to YAML?: Pair with env-to-yaml. The round-trip is lossless for simple data; complex values that got JSON-encoded need the inverse parsing.

A worked example, rendered from real sample data. Sign in to run the tool on your own input.

Input

app:
  name: myapp
  port: 3000
database:
  host: localhost
  user: postgres

Output

APP_NAME=myapp
APP_PORT=3000
DATABASE_HOST=localhost
DATABASE_USER=postgres

Flatten a YAML file to KEY=value lines. Part of the DevTools Surf developer suite. Browse more tools in the Converters collection.

YAML was first proposed in 2001 by Clark Evans, and its name originally stood for 'Yet Another Markup Language' before being changed to 'YAML Ain't Markup Language.'
The .env file convention was popularized by the Twelve-Factor App methodology published by Heroku in 2011, which advocates storing config in environment variables.
Docker Compose introduced YAML-based service configuration in 2014, making YAML-to-env conversion a common DevOps task.

How does it flatten nested YAML?: Dot path becomes underscore-separated UPPER_CASE: `db.host` → `DB_HOST`. Arrays use numeric suffixes (`ITEMS_0`, `ITEMS_1`).
What about complex values?: Objects and arrays can't be .env-native. They become JSON-stringified strings: `SERVERS='["a.com","b.com"]'`.
Are comments kept?: Stripped — .env supports comments but YAML-to-.env focuses on the data. Add top-level `# generated from config.yaml` manually if you want provenance.
Round-trip to YAML?: Pair with env-to-yaml. The round-trip is lossless for simple data; complex values that got JSON-encoded need the inverse parsing.