---
title: API reference | SendHQ Docs
description: Complete SendHQ API reference for emails, drafts, templates, domains, inbound email, deliverability, billing, and account administration.
canonical: https://sendhq.cc/docs/api-reference
last-updated: 2026-09-07
---
# One contract for the complete customer surface.

Customer endpoints are available under `/api/v1`. The legacy `/api` prefix remains available to the dashboard, while new server integrations should use the versioned base URL.

**63** documented operations **8** resource groups **OpenAPI 3.1** machine-readable contract

## Authentication boundaries

Product integrations use a workspace API key, which can also read account usage, analytics, and API-key metadata. Billing changes and API-key creation or revocation require the HTTP-only browser session and are labeled accordingly.

## Resources

- [8 operations](https://sendhq.cc/docs/api-reference/emails.md): Emails and threads Send, retrieve, search, reply, and inspect delivery events.
- [8 operations](https://sendhq.cc/docs/api-reference/labels.md): Labels and filing rules Organize sent and received mail into folders automatically or by hand.
- [9 operations](https://sendhq.cc/docs/api-reference/drafts.md): Drafts and attachments Build composer flows with private attachment storage.
- [10 operations](https://sendhq.cc/docs/api-reference/templates.md): Hosted templates Draft, render, test, version, publish, and send reusable content.
- [7 operations](https://sendhq.cc/docs/api-reference/domains.md): Domains Provision sender identities and understand DNS verification state.
- [8 operations](https://sendhq.cc/docs/api-reference/inbound.md): Inbound email Create addresses and work with received conversations.
- [5 operations](https://sendhq.cc/docs/api-reference/deliverability.md): Deliverability Inspect events, reputation outcomes, and blocked recipients.
- [8 operations](https://sendhq.cc/docs/api-reference/account.md): Account and billing Read account usage, analytics, and key metadata with an API key; billing changes and key creation or revocation require a dashboard session.

## Error envelope

JSON errors use one predictable envelope. Status codes distinguish invalid input, authentication, missing resources, conflicts, payment requirements, safety blocks, and usage limits.

```json
{
  "error": {
    "message": "The sender domain is not verified",
    "status": 403
  }
}
```

## Versioning

The date-based API version identifies this contract. Backward-compatible fields can be added within the version. Breaking changes require a new versioned base path and a documented transition.

```json
{
  "version": "2026-09-07",
  "baseUrl": "https://sendhq.cc/api/v1",
  "openapi": "https://sendhq.cc/openapi.json"
}
```