ClickSend REST API v3

Name: ClickSend REST API v3 API
Brand: ClickSend REST API v3
Availability: InStock

★ Only Publicly Available OpenAPI DocumentCommunicationsSms Messagingbasic205 EndpointsREST

For 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.

Quickstart

Get started with ClickSend REST API v3 in minutes using your preferred integration method.

# Add to your MCP client config (Claude Desktop, Cursor, Windsurf)
{
  "jentic": {
    "url": "https://api.jentic.com/mcp",
    "auth": "oauth"
  }
}

# Then ask your agent:
"send a transactional SMS to a customer"

# → Jentic returns the GET /events tool with parameter schema, agent executes.

Capabilities

What an agent can do with ClickSend REST API v3 API.

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

GET STARTED

Start building with ClickSend REST API v3 API

Explore with Jentic

View OpenAPI Document

Jentic publishes the only available OpenAPI document for ClickSend REST API v3, keeping it validated and agent-ready.

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.

Use Cases

Patterns agents use ClickSend REST API v3 API for, with concrete tasks.

★ 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.

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.

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.

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 the Jentic vault. Total integration time: under an hour.

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

205 endpoints — jentic publishes the only available openapi specification for clicksend rest api v3, keeping it validated and agent-ready.

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

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

Why though Jentic?

Three things that make agents converge on Jentic-routed access.

Credential isolation

ClickSend username and API key are stored encrypted in the Jentic vault. Agents receive scoped tokens and never see the Basic auth credentials.

Intent-based discovery

Agents search Jentic with intents like 'send a transactional SMS' or 'post a physical letter' and Jentic returns the matching ClickSend operations with their input schemas.

Time to first call

Direct ClickSend integration: 2-4 days to handle Basic auth, channel selection, and delivery report parsing across 205 endpoints. Through Jentic: under 1 hour — search, load schema, execute.

Related APIs

Alternatives and complements available in the Jentic catalogue.

Complementary

ClickMeter

ClickMeter tracks clicks on the links inside ClickSend SMS or email messages.

Use ClickMeter alongside ClickSend when an agent needs to attribute click-throughs from a sent campaign back to recipient or channel.

Complementary

ClickMeter v2

Full v2 ClickMeter surface for aggregated reporting on clicks generated by ClickSend campaigns.

Pair when an agent dispatches a campaign through ClickSend and needs aggregated click and conversion analytics afterwards.

Complementary

Clientary

Clientary handles invoicing; ClickSend can dispatch the resulting invoice notification by SMS, email, or post.

Pair when an agent generates an invoice in Clientary and needs to deliver it across SMS, email, or physical mail.

FAQs

Specific to using ClickSend REST API v3 API through Jentic.

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 at https://app.jentic.com/sign-up.

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.