Environment Variable Template Expander

Environment Variable Template Expander

Paste a template containing variable placeholders along with your environment variables, and instantly see the fully expanded result. Supports ${VAR}, {{VAR}}, %VAR%et $VAR syntaxes, with auto-detection to handle all four in the same template. Unresolved placeholders are highlighted in a sidebar so you can see at a glance which keys are missing.

The whole thing runs in your browser. Nothing is uploaded to a server, which matters when you are pasting actual secrets while previewing a config render. The substitution is deterministic, so the output you see is exactly what a build pipeline using the same placeholders would produce.

Comment utiliser

1. Paste your template into the Modèle box. It can be YAML, JSON, an Nginx config, a docker-compose file — anything that contains placeholders.
2. Collez votre .env contents (or any list of KEY=value pairs) into the Variables d'environnement box. Comments, quoted values, and the export prefix are all parsed correctly.
3. Choisissez un Variable Syntax. Leave it on auto-detect if your template mixes styles, or lock it to a single syntax if you want strict matching.
4. Choose how to handle unresolved variables: leave the original placeholder in place, or strip it to an empty string.
5. Copy or download the expanded output. The summary bar shows the resolved/unresolved counts and the unresolved list shows each missing name with its occurrence count.

Caractéristiques

• Four placeholder syntaxes – ${VAR} (shell, Docker Compose), {{VAR}} (Handlebars, Mustache), %VAR% (Windows batch), and bare $VAR (POSIX shell).
• Auto-detect mode – mix all four syntaxes in the same template and expand them in one pass.
• Standards-compliant .env parser , les séparateurs espaces, et les continuations de ligne avec un backslash de la même manière # comments, single/double-quoted values, the export KEY=value form, and inline trailing comments.
• Unresolved variable report – each missing placeholder is listed with the number of times it appears in the template.
• Case-sensitivity toggle – match keys exactly or fall back to case-insensitive lookups for cross-platform configs.
• Two unresolved-handling modes – leave placeholders intact for debugging, or substitute empty strings for a clean preview.
• Prévisualisation en temps réel – the output regenerates as you type, with a short debounce so it stays smooth on large templates.
• Première confidentialité – substitution runs entirely client-side, so your variables and secrets never leave the browser.

Cas d'utilisation courants

• CI/CD template preview – see exactly what a GitHub Actions or GitLab CI pipeline will produce after variable substitution.
• Docker Compose interpolation – verify how ${VAR} placeholders resolve before docker compose up.
• Kubernetes manifest preview – preview a Helm-like substitution without spinning up a templating tool.
• Config file generation – render Nginx, Apache, or HAProxy configs from a single template per environment.
• Secrets injection sanity check – preview the file a deployment will receive without leaking secrets to a log.
• Documentation rendering – fill in versioned {{VAR}} placeholders in README or markdown snippets.