API Reference
API Reference
Complete reference for the send0 REST API.
Base URL
All API requests are made to:
https://api.send0.dev/v1Authentication
Authenticate by including your API key in the Authorization header of every request.
Authorization: Bearer sk_live_...Note: Never expose your API key in client-side code. All API calls should be made from your server.
Request format
- All request bodies must be JSON with
Content-Type: application/json - All responses are JSON
- All timestamps are ISO 8601 (e.g.,
2026-04-12T10:30:00Z) - IDs are prefixed strings (e.g.,
em_,con_,tmpl_,dom_)
Pagination
All list endpoints use cursor-based pagination. The response includes:
| Field | Type | Description |
|---|---|---|
data | array | Array of resource objects |
has_more | boolean | Whether more results exist |
cursor | string | Cursor to pass for the next page |
Pass the cursor value as a query parameter to retrieve the next page of results.
Rate limiting
Rate limit information is included in the response headers of every request. If you exceed the limit, you will receive a 429 Too Many Requests response.
Request ID
Every response includes an X-Request-ID header. Include this when contacting support for faster debugging.
Response headers
Content-Type: application/json
X-Request-ID: req_7mKpLvRw9nQx
X-Send0-Version: 2026-04-12
X-RateLimit-Limit: 100
X-RateLimit-Remaining: 94
X-RateLimit-Reset: 1712922000Resources
| Resource | Description |
|---|---|
| Emails | Send, track, and manage emails |
| Contacts | Manage your contact list |
| Templates | Create and manage email templates |
| Domains | Add and verify sending domains |
| Webhooks | Configure webhook endpoints |
| API Keys | Create and manage API keys |