Templates and Variables

Build dynamic emails with variables, conditionals, loops, and formatting helpers that resolve at send time. There are two ways to send with variables, each with its own rendering engine:

Endpoint	Variables field	Engine
`POST /v1/send-template-email`	`variables`	Simple substitution: `{var}` or `{{var}}`, fallbacks with a default value, and `{{#each}}` loops
`POST /send-email` (advanced API)	`data`	Full Handlebars: `{{#if}}` conditionals, helpers, and nested properties

Basic concepts

Variables

Insert dynamic values into your template with {{variableName}}. In the template:

<h1>Hello, {{name}}!</h1>
<p>Your account at {{company}} has been created successfully.</p>

In the request body (public v1 API):

{
  "template_id": "550e8400-e29b-41d4-a716-446655440000",
  "variables": {
    "name": "Carlos",
    "company": "TechStore"
  }
}

Rendered result:

<h1>Hello, Carlos!</h1>
<p>Your account at TechStore has been created successfully.</p>

In /v1/send-template-email (the variables field), additionally:

{variableName} with a single brace is equivalent to {{variableName}}.
You can define a fallback with {variable || "default value"} for when the variable doesn’t exist.
Values are HTML-escaped by default; use {!variable} to insert unescaped HTML.
Variables with no value (and no fallback) render as an empty string.

In the advanced API (/send-email, the data field), always use double braces {{variable}}. Single braces and || fallbacks are not available, and values are inserted without HTML escaping.

Conditionals

Available only in the advanced API (POST /send-email, the data field). /v1/send-template-email does not support {{#if}} blocks.

Use {{#if variable}}...{{/if}} to show content only when a variable exists and is truthy. Use {{else}} for the opposite case. In the template:

{{#if premium}}
  <p>Thanks for being a Premium member. You get free shipping on all your orders.</p>
{{else}}
  <p>Upgrade to Premium to get free shipping.</p>
{{/if}}

In the request body:

{
  "data": {
    "premium": true
  }
}

Note: Handlebars evaluates the values false, undefined, null, "", 0, and empty arrays [] as falsy.

Loops

Use {{#each array}}...{{/each}} to iterate over a list. Available in both APIs, with different syntax inside the block. In the advanced API (/send-email, the data field), {{this}} is the current item. Access its properties with {{this.property}} and use helpers:

<table>
  <tr>
    <th>Product</th>
    <th>Quantity</th>
    <th>Price</th>
  </tr>
  {{#each products}}
  <tr>
    <td>{{this.name}}</td>
    <td>{{this.quantity}}</td>
    <td>{{formatCurrency this.price}}</td>
  </tr>
  {{/each}}
</table>

In the request body:

{
  "data": {
    "products": [
      { "name": "Blue T-Shirt", "quantity": 2, "price": 15990 },
      { "name": "Black Pants", "quantity": 1, "price": 29990 },
      { "name": "White Sneakers", "quantity": 1, "price": 45990 }
    ]
  }
}

Special variables inside loops (advanced API):

Variable	Description
`{{this}}`	The current item of the iteration
`{{@index}}`	Index of the item (starts at 0)
`{{@first}}`	`true` if it’s the first item
`{{@last}}`	`true` if it’s the last item
`{{@key}}`	The current key (when iterating an object)

In /v1/send-template-email (the variables field), the current item’s properties are exposed directly: use {{name}}, not {{this.name}} (the this. notation is not supported). Special variables: @index, @first, @last, @odd, and @even. There are no formatting helpers: send the values already formatted.

Built-in helpers

RQE includes additional Handlebars helpers for common formatting in transactional emails.

Helpers are available only in the advanced API (POST /send-email, the data field). In /v1/send-template-email, send the values already formatted.

`formatCurrency`

Formats a number as currency using en-US formatting. Defaults to USD. Accepts an optional second parameter for the currency.

<p>Total: {{formatCurrency total}}</p>

With "total": 61970 it produces: $61,970.00 To use another currency:

<p>Total: {{formatCurrency total "CLP"}}</p>

`multiply`

Multiplies two numeric values. The result is rounded to 2 decimals.

<p>Subtotal: {{formatCurrency (multiply quantity price)}}</p>

`formatDate`

Formats an ISO 8601 date into a human-readable Spanish format (es-ES). Accepts an optional second parameter for the format. Default format (short):

<p>Date: {{formatDate deliveryDate}}</p>

With "deliveryDate": "2025-03-15T00:00:00Z" it produces: 15/3/2025 Long format (long):

<p>Date: {{formatDate deliveryDate "long"}}</p>

With "deliveryDate": "2025-03-15T00:00:00Z" it produces: sábado, 15 de marzo de 2025

`default`

Provides a default value when the variable is falsy (undefined, null, "", 0, or false).

<p>Hello, {{default name "Customer"}}!</p>

If name is not defined in data, it renders as Hello, Customer!.

`json`

Serializes an object to JSON with indentation. Useful for debugging or including structured data in the email.

<pre>{{json data}}</pre>

With "data": {"key": "value"} it produces:

{
  "key": "value"
}

The text helpers capitalize, uppercase, and lowercase are also available to transform strings.

Identifying a template

You can reference a template in two ways in the public API (/v1/send-template-email):

Field	Type	Description
`template_id`	string (UUID)	Unique UUID of the template
`template_internal_id`	number	Auto-incremented internal ID (per project)

{
  "template_id": "550e8400-e29b-41d4-a716-446655440000",
  "recipient_email": "user@example.com",
  "sender_email": "store@yourdomain.com",
  "variables": {
    "name": "Ana",
    "orderNumber": "5021"
  }
}

If the template doesn’t exist, the API returns a 404 error.
template_internal_id is resolved within the project associated with the API key used.

In the advanced API (/send-email), the templateId field accepts the template’s UUID or its numeric internal ID, always within the project associated with the API key.

The `variables` object

In /v1/send-template-email, the variables object is a JSON where each key is a template variable. Values are converted to strings when rendering. Variables the template uses but that don’t exist render as an empty string (or with their || fallback if defined).

Complete example

Request:

curl -X POST https://api.reallyquickemails.com/v1/send-template-email \
  -H "Authorization: Bearer sk_proj_xxxxxxxxxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "template_id": "550e8400-e29b-41d4-a716-446655440000",
    "recipient_email": "john.doe@example.com",
    "sender_email": "orders@mystore.com",
    "variables": {
      "name": "John",
      "orderNumber": "3847",
      "purchaseDate": "February 20, 2026",
      "products": [
        { "product": "Bluetooth Headphones", "quantity": 1, "price": "$34.990" },
        { "product": "USB-C Cable", "quantity": 3, "price": "$5.990" }
      ],
      "total": "$52.960"
    }
  }'

Corresponding template (v1 syntax):

<h1>Thanks for your purchase, {{name}}!</h1>
<p>Order #{{orderNumber}} - {{purchaseDate}}</p>

<table>
  {{#each products}}
  <tr>
    <td>{{product}}</td>
    <td>x{{quantity}}</td>
    <td>{{price}}</td>
  </tr>
  {{/each}}
</table>

<p><strong>Total: {{total}}</strong></p>
<p>Handled by: {salesRep || "our team"}</p>

This engine does not include formatting helpers: send prices and dates already formatted as strings. For conditionals, helpers, or nested properties, use the advanced API (POST /send-email) with templateId + data.

Accessing nested properties

In the advanced API (/send-email, the data field), use dot notation to access nested objects:

<p>City: {{address.city}}</p>
<p>Region: {{address.region}}</p>

{
  "data": {
    "address": {
      "city": "Santiago",
      "region": "Metropolitana"
    }
  }
}

In /v1/send-template-email, dot notation is not supported: flatten the variables before sending them (for example address_city instead of address.city).

Best practices

Define default values for optional variables: in the advanced API use the default helper; in v1 use {variable || "value"} fallbacks. This avoids blank spaces in the email.
Validate your variables before sending. Variables the template expects but that don’t exist render as empty strings, without error.
Store the template_id (UUID) in your configuration, or use template_internal_id if you prefer short numeric IDs per project.
Test your templates with sample data before integrating. In the advanced API use dry_run: true to render without sending — see Dry Run.

Guides

The app

Concepts

API Reference

Basic concepts

Variables

Conditionals

Loops

Built-in helpers

`formatCurrency`

`multiply`

`formatDate`

`default`

`json`

Identifying a template

The `variables` object

Complete example

Accessing nested properties

Best practices

​Basic concepts

​Variables

​Conditionals

​Loops

​Built-in helpers

​formatCurrency

​multiply

​formatDate

​default

​json

​Identifying a template

​The variables object

​Complete example

​Accessing nested properties

​Best practices

Basic concepts

Variables

Conditionals

Loops

Built-in helpers

`formatCurrency`

`multiply`

`formatDate`

`default`

`json`

Identifying a template

The `variables` object

Complete example

Accessing nested properties

Best practices