Developer Tools
Mustache Template Tester
Render Mustache templates against a JSON context in your browser. Supports sections, inverted sections, partials, custom delimiters, and dotted names.
Quick examples
Click an example to load a template, JSON context, and partials.
Mustache v1.4 grammar. Sections, inverted sections, partials, custom delimiters, and dotted-name lookup are all supported. Lambdas are disabled for safety: the tool never evaluates code from your context.
Map partial names to template strings. Used by {{> name}} tags.
Rendered output
217 characters, 9 lines.
Hello Mert! You have 3 new messages. - [high] Build passed from ci@example.com - [low] Weekly digest from news@example.com - [low] Receipt #4521 from billing@example.com Visit https://zerosignuptools.com/ for more.
Referenced variables
Every variable name the parser found in the template, including section, inverted, partial, and dotted-name tags.
- count
- from
- messages
- name
- priority
- site.url
- subject
Mustache syntax cheat sheet
- {{name}} HTML-escaped variable
- {{{name}}} or {{&name}} unescaped variable
- {{#name}}...{{/name}} section: iterate arrays, push objects, or render once for truthy values
- {{^name}}...{{/name}} inverted section: renders when the value is falsy or empty
- {{!comment}} comment, omitted from the output
- {{> partial}} partial lookup, indented to match the tag column
- {{=<% %>=}} change delimiters for the rest of the template
- {{.}} implicit iterator: the current item inside a section
- {{a.b.c}} dotted name walks nested objects from the resolved root
- Standalone tags strip the surrounding whitespace and one trailing newline, matching the Mustache v1.4 spec.
Compatible with Mustache.js, Handlebars (variables and core blocks), Mustache for Python (pystache), and Go's text/template Mustache-style helpers.
How to use
- Paste your Mustache template into the Template box. Tags use {{ and }} by default; switch with {{=<% %>=}} if your tooling expects another pair.
- Paste a JSON object into the JSON context box. Top-level keys can be referenced directly; nested keys use dotted-name lookup ({{user.email}}).
- Optional: add a Partials JSON map of partial name to template string so {{> name}} tags resolve.
- Read the rendered output below. The Referenced variables panel shows which names resolved (green) and which were missing from the context (amber).
- Use the example chips at the top to load a working template, context, and partials pair for sections, inverted sections, partials, dotted names, and custom delimiters.
- Click Copy output to copy the rendered text, ready to paste into your email tool, Slack message, or template config.
About this tool
Mustache Template Tester renders Mustache and Handlebars-style templates against a JSON context entirely in your browser. The implementation covers the Mustache v1.4 grammar that real-world templates rely on: HTML-escaped variables ({{name}}), unescaped variables ({{{name}}} or {{&name}}), sections ({{#name}}...{{/name}}), inverted sections ({{^name}}...{{/name}}), comments ({{!...}}), partial lookups ({{> name}}) with automatic indentation, custom delimiters ({{=<% %>=}}), dotted-name access ({{a.b.c}}) with standard context-stack fallback, and the implicit iterator ({{.}}) for arrays of scalars. Standalone tags strip their surrounding whitespace and the single trailing newline so block tags do not leave blank lines behind, matching the published spec. The renderer never evaluates code from your JSON: lambdas and function values are skipped intentionally so a pasted context can never run arbitrary JavaScript on the page. Partials are supplied through a separate JSON map of name to template string, which means you can model multi-file template setups (Twilio SMS, Mailgun emails, GitHub Actions matrices, Helm chart values, CloudFormation outputs, Salesforce Apex, AWS SES, Mustache.js bundles, Hugo-style includes) without uploading anything. The result panel reports the rendered output, the character and line counts, and a list of every referenced variable with a coloured indicator showing which names resolved against the supplied context, which makes it easy to spot a typo in a key. The cheat sheet block summarizes the Mustache grammar, and a Plain text or Wrap output toggle controls how long lines display. Useful when debugging a transactional email template, previewing a Slack notification format, sanity-checking a Twilio SMS template before deploying it, validating that a Helm or CloudFormation Mustache-style template will render against your values, or just learning the Mustache spec interactively. Everything stays on your device. Templates, context JSON, partials, and the rendered output are never uploaded.
Free to use. Works in your browser. No signup, no login.
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