API · Templates

Create Template

Create a draft email template (requires full access). Variables are inferred from inline merge tags unless explicit definitions are supplied.

POST/templatesFull access

Request parameters

Parameter	Type	Description
`Idempotency-Key` header · optional	`string` 1–256 characters	Makes the request safe to retry. See Idempotency.
`name` body · required	`string`	Template name, up to 256 characters.
`alias` body · optional	`string \| null`	Unique template alias, up to 128 characters, generated when omitted on creation.
`from` body · optional	`string \| null`	Sender address, up to 512 characters, optionally formatted as Name <sender@example.com>.
`subject` body · optional	`string \| null`	Email subject, up to 998 characters.
`reply_to` body · optional	`string \| (string)[]`	Up to 50 valid reply-to addresses, supplied as a string or array.
`html` body · required	`string`	HTML content, up to 256 KiB, with variable values escaped when rendered.
`text` body · optional	`string \| null`	Plain text content, up to 256 KiB, derived from HTML when omitted on creation; an explicit empty string stays empty.
`variables` body · optional	`(object)[]` Up to 50 items	Up to 50 unique string or number variable definitions, overriding inferred inline variables.
`variables[].key` body · required	`string` Matches /^[A-Za-z_][A-Za-z0-9_]*$/	Unique identifier of up to 50 characters, excluding FIRST_NAME, LAST_NAME, EMAIL, RESEND_UNSUBSCRIBE_URL, contact, and this.
`variables[].type` body · required	`"string" \| "number"`	Variable type: string or number.
`variables[].fallback_value` body · optional	`string \| number`	Default matching the variable type, with string defaults limited to 2000 characters.

Request example

Set OPENSEND_BASE_URL=https://api.example.com and OPENSEND_API_KEY=os_replace_me on your server.

bash

curl -X POST "$OPENSEND_BASE_URL/templates" \
  -H "Authorization: Bearer $OPENSEND_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"name":"Welcome","html":"<p>Hello.</p>"}'

Response

201 · application/json. Example IDs stand for IDs returned by your installation.

json

{
  "object": "template",
  "id": "YOUR_ID"
}

Behavior and errors

A template has one mutable draft and one published snapshot. Sends must use the published snapshot. There is no historical version API.

Use a full-access credential. Resource IDs belong to your team; an unknown or foreign resource returns 404. See authentication, errors, rate limits, and compatibility for the shared contract.