canonical: https://jentic.com/apis/clicksend.com/clicksend

# ClickSend REST API v3

Jentic publishes the only available OpenAPI specification for ClickSend REST API v3, keeping it validated and agent-ready. ClickSend is a multi-channel business messaging platform covering SMS, MMS, voice, fax, email, and postal mail (letters and postcards). The 205-endpoint v3 surface exposes contact list management, send and history endpoints for each channel, automation rules for inbound and receipt handling, account recharge and pricing, geolocation lookups, and detailed delivery reporting. Authentication uses HTTP Basic with the username and an API key obtained from the ClickSend dashboard.

## For AI agents

Send SMS, MMS, voice calls, faxes, emails, and postal letters from a single account, manage contact lists, and pull delivery and pricing data so agents can run cross-channel outbound campaigns.

## Scope

Does not handle inbound voice IVR, video conferencing, or marketing automation journey orchestration - use for outbound SMS, MMS, voice, fax, email, and physical mail dispatch only.

## Capabilities

- Send SMS and MMS messages to one or many recipients with scheduling and per-message sender ID
- Place outbound voice calls with text-to-speech messages and choose voice, language, and gender
- Dispatch fax documents to international fax numbers and track per-page delivery results
- Post physical letters and postcards with address validation and PDF artwork upload
- Manage contact lists, individual contacts, and contact suggestions for reusable recipient targeting
- Configure automation rules for inbound SMS, fax, email, and delivery receipt callbacks
- Pull pricing and country lookups so agents can quote a campaign cost before sending

## Use cases

### Multi-Channel Customer Notifications

Operations teams use ClickSend to send appointment reminders, delivery updates, and outage alerts via SMS, with email or voice fallback for unreachable contacts. The single API removes the need to integrate separate vendors per channel - one set of credentials, one billing account, one delivery report stream covering five outbound channels.

Example prompt: Send the SMS 'Your appointment is at 10am tomorrow' to +61411111111 and confirm the message was queued

### Programmatic Direct Mail

ClickSend exposes endpoints under /post/letters and /post/postcards to dispatch physical mail through its print and postal partners. Marketing teams trigger letters from CRM events - renewal notices, win-back postcards, regulatory documents - without operating their own print infrastructure. End-to-end setup takes a few hours including PDF artwork validation.

Example prompt: Submit a letter PDF to a recipient address with postal code 11111 and confirm the submission returned a success status

### Inbound Reply Automation

Recipients reply to an SMS or fax and the response is routed back through automation rules configured under /automations/sms/inbound and /automations/fax/inbound. Teams build keyword-driven autoresponders, opt-out handling, and inbound triage logic without standing up custom webhook receivers - the rules engine handles routing and the API returns parsed inbound history.

Example prompt: Create an inbound SMS automation rule that forwards any reply containing 'STOP' to an opt-out webhook URL

### Agent-Driven Campaign Send

An AI agent receives a brief - 'send tonight's outage notice to all NSW customers' - checks pricing via /sms/price, segments the contact list, dispatches the SMS, and pulls delivery reports. Through Jentic, the agent searches for 'send a transactional SMS', loads the operation, and executes against credentials in your Jentic One instance. Total integration time: under an hour.

Example prompt: Quote the cost of sending an SMS to 500 Australian mobile numbers, then dispatch the campaign and return delivered count after 5 minutes

## Key endpoints

| Method | Path | Description |
| --- | --- | --- |
| POST | /account | Create a ClickSend account |
| POST | /automations/sms/inbound/ | Create an inbound SMS automation rule |
| GET | /automations/sms/receipts | List SMS receipt automation rules |
| POST | /automations/fax/inbound | Create an inbound fax automation rule |
| GET | /account/usage/{year}/{month}/{type} | Get monthly usage by message type |
| POST | /automations/email/receipt | Create an email receipt automation rule |

## Key resources

- **SMS** — Send, schedule, and pull history for SMS messages
- **MMS** — Send multimedia messages with attached media files
- **Voice** — Make outbound voice calls with text-to-speech messages
- **Fax** — Send and receive faxes with per-page delivery tracking
- **Email Marketing** — Send marketing emails and manage campaigns and templates
- **Post Letter / Post Postcard / Post Direct Mail** — Send physical mail through ClickSend's print and postal partners
- **Contacts and Contact Lists** — Store and segment recipients for reuse across channels
- **Automation Rules** — Configure inbound and receipt automation across SMS, fax, and email
- **Pricing and Countries** — Look up per-channel and per-country pricing before dispatch

## Why Jentic

- **Setup:** Wiring the ClickSend REST API by hand means setting up Basic auth against rest.clicksend.com/v3 and mapping the right call across SMS, MMS, voice, fax, email, and physical mail yourself. Through Jentic you install once, import the ClickSend REST API v3 from the API Directory, store the username and API key once, and your agent calls it.
- **Permission scoping:** ClickSend takes recipients and message content in the request body, so scope the agent to the operations it needs, such as sending a transactional SMS or posting a letter. You choose which operations are in the allowed set, so account changes and other channels are not callable unless you add them.
- **Credential handling:** Your ClickSend username and API key are stored once, encrypted, by your own Jentic One instance and injected at execution time. They never enter the agent's prompt, logs, or context.
- **Discovery method:** Agents search Jentic by intent such as 'send a transactional SMS' or 'post a physical letter', and Jentic returns the matching ClickSend operation with its input schema so the agent calls the right endpoint without browsing the reference docs.

## Related APIs

- **ClickMeter** — ClickMeter tracks clicks on the links inside ClickSend SMS or email messages.
- **ClickMeter v2** — Full v2 ClickMeter surface for aggregated reporting on clicks generated by ClickSend campaigns.
- **Clientary** — Clientary handles invoicing; ClickSend can dispatch the resulting invoice notification by SMS, email, or post.

## FAQ

### Why is there no official OpenAPI spec for ClickSend REST API v3?

ClickSend does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call ClickSend REST API v3 via structured tooling. It is validated against the live API and kept up to date. Get started with Jentic One, the self-hosted execution layer.

### What authentication does the ClickSend REST API use?

The ClickSend REST API uses HTTP Basic authentication. The username is your ClickSend username and the password is your API key from the dashboard, base64-encoded and sent in the Authorization header. Through Jentic, both values are stored encrypted in the vault and never enter the agent's context.

### Can I send a physical letter with the ClickSend API?

Yes. ClickSend exposes Post Letter and Post Postcard endpoints under /post/letters and /post/postcards. You upload a PDF or supply HTML artwork, provide the recipient address, and ClickSend's print and postal partners dispatch the physical item. Address validation is available via the Post Address Detection endpoint.

### What are the rate limits for the ClickSend REST API?

ClickSend returns HTTP 429 with a TOO_MANY_REQUESTS body when limits are exceeded; the spec does not declare numeric thresholds. Limits are tied to the account plan visible in the ClickSend dashboard. Jentic surfaces 429 responses as standard error objects so agents can apply their own retry-with-backoff.

### How do I send an SMS through the ClickSend API via Jentic?

Run pip install jentic, then search Jentic for 'send a transactional sms' to find the SMS send operation. Load the operation schema, supply recipient list and body, and execute. Jentic injects the Basic auth header from the vault and returns the queued response with message ID and cost.

### Can I look up the price of a message before sending it?

Yes. The Pricing endpoints return per-channel and per-country rates so an agent can quote a campaign cost before dispatch. This is useful for batch campaigns where the agent needs to confirm budget before triggering the send.

### Can I limit what my agent is allowed to do with the ClickSend REST API?

Yes. Because you run your own self-hosted Jentic One instance, your own rules decide which ClickSend operations and credentials the agent may use. Since ClickSend takes recipients and message content in the request body, you can scope the agent to just the operations it needs, such as sending a transactional SMS or posting a letter, and leave everything else out of the allowed set. Account changes and other channels like voice, fax, or email stay uncallable unless you explicitly add them.