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.

Install Jentic One Beta

Connect the ClickSend REST API v3 to your agent

Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the ClickSend REST API v3, or any other public or private API you need. You set the rules, the agent never sees your credentials, and every call is logged.

Two steps, two machines. Install the instance in a safe environment, then register your agent from wherever it runs.

Step 1: Jentic One Host machine

# On the machine that will host your Jentic One instance:
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh

Step 2: Agent machine

# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL https://raw.githubusercontent.com/jentic/jentic-one/main/tools/install.sh | sh
jentic register       # connects your agent to your Jentic One instance

Jentic One is in public beta. The setup above keeps your agent separate from the instance, which is what you want before using real credentials: an agent running as the same OS user as Jentic One can read its stored keys directly. Just evaluating? A single local install is fine to start. See the secure deployment guide for the tiers.

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

GET STARTED

Start building with ClickSend REST API v3 API

Explore with Jentic

View OpenAPI Document

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 your Jentic One instance. 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 Jentic?

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

Credential isolation

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.

Intent-based discovery

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.

Time to first call

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 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.

ClickSend REST API v3

Connect the ClickSend REST API v3 to your agent

Capabilities

Start building with ClickSend REST API v3 API

Use Cases

Key Endpoints

Why Jentic?

Related APIs

FAQs