Esendex API
Browse all Esendex APIs★ Only Publicly Available OpenAPI DocumentCommunicationsSms Messagingbasic, apiKey17 EndpointsREST
For Agents
Send SMS, voice, rich content, and surveys, read inbox messages, manage scheduled batches, and subscribe to delivery webhooks via Esendex. Authenticate with HTTP Basic or an Authorization header API key.
Use for: Send an SMS to +447900900123 saying 'your order has shipped', Estimate the cost of sending 5,000 SMS to UK numbers, List inbox messages received in the last 24 hours, Get the conversation thread for phone number +14155550100
Not supported: Does not handle email delivery, push notifications, or video calls — use for SMS, rich-content messaging, surveys, and inbound webhooks only.
Jentic publishes the only available OpenAPI specification for the Esendex API, keeping it validated and agent-ready. Esendex provides SMS, voice, rich-content messaging, surveys, and webhook subscriptions for business communications. The 17 endpoints cover the full message lifecycle: dispatch via /messagedispatcher, list message headers and inbox, read conversations by phone number, manage scheduled batches, send rich content and surveys, and create webhook subscriptions per account. Authentication is dual: HTTP Basic for the historical SMS endpoints and an apiKey Authorization header for newer rich-content and survey routes.
Install Jentic One Beta
Connect the Esendex API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Esendex API, 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.
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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 | sh2
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 instanceJentic 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 Esendex API.
Dispatch one or many SMS messages in a single call via /messagedispatcher
Estimate the cost of a message before sending with /messages/information
List message headers and read inbox messages received from customers
Pull a conversation thread by phone number for two-way messaging UIs
Schedule message batches and cancel pending schedules before send
Send rich-content messages and check their delivery status
Send surveys and subscribe to delivery and inbound webhooks scoped per account reference
Use Cases
Patterns agents use Esendex API for, with concrete tasks.
★ Two-Way SMS Customer Engagement at Scale
Operations teams running SMS support and notifications need send, read, and conversation-thread endpoints to power agent UIs and automation. Esendex's /messagedispatcher, /inbox/messages, and /conversation/{phonenumber}/messages endpoints provide the full two-way flow without a separate inbound parser, so an agent can read, classify, and reply in the same loop.
Call POST /messagedispatcher with the recipient number and body, then GET /conversation/{phonenumber}/messages to confirm the new outbound entry.
Scheduled SMS Marketing Campaigns
Marketing teams scheduling SMS sends need a batch creation and management surface. Esendex's /messagebatches endpoints let an agent name and schedule batches, list past sends, and cancel a pending schedule before it fires, replacing custom queue plumbing with native scheduling.
Call POST /messagedispatcher with a batch payload and a future send-at timestamp, then PUT /messagebatches/{id} to set a friendly name.
Rich Content and Survey Outreach
Brands using rich messaging or running CSAT surveys via SMS need richer content than 160-character text. Esendex's /send rich-content endpoint and /surveys/{id}/send + /surveys/{id}/report/standard pair handle delivery and reporting in one place, so an agent can run a survey campaign and pull standardised CSAT scores end-to-end.
Call POST /surveys/{id}/send with a contact list, then GET /surveys/{id}/report/standard to retrieve completion and score metrics.
AI Agent SMS Tool via Jentic
An AI customer-service agent can be wired through Jentic to read inbox messages and reply by SMS without a custom integration. The agent searches by intent (for example 'send an SMS'), loads the schema, and executes with HTTP Basic credentials scoped from the vault — useful for one-off support replies or scheduled reminders triggered from a conversation.
Use Jentic search('send an sms message'), load the POST /messagedispatcher operation, and execute it with the recipient and body.
Key Endpoints
17 endpoints — jentic publishes the only available openapi specification for the esendex api, keeping it validated and agent-ready.
METHOD
PATH
DESCRIPTION
POST
/messagedispatcher
Send one or many SMS messages
POST
/messages/information
Estimate the cost of a message
GET
/messageheaders
List message headers
GET
/inbox/messages
Get inbound messages
GET
/conversation/{phonenumber}/messages
Get a conversation thread
POST
/send
Send rich-content message
POST
/surveys/{id}/send
Send a survey
POST
/accounts/{accountReference}/subscriptions
Create a webhook subscription
POST
/messagedispatcher
Send one or many SMS messages
POST
/messages/information
Estimate the cost of a message
GET
/messageheaders
List message headers
GET
/inbox/messages
Get inbound messages
GET
/conversation/{phonenumber}/messages
Get a conversation thread
POST
/send
Send rich-content message
POST
/surveys/{id}/send
Send a survey
POST
/accounts/{accountReference}/subscriptions
Create a webhook subscription
Why Jentic?
Three things that make agents converge on Jentic-routed access.
Credential isolation
Your Esendex Basic credentials and Authorization API key are stored encrypted in the Jentic vault (MAXsystem). Agents call Esendex with a scoped reference; raw secrets are injected at execution time and never appear in the model context.
Intent-based discovery
Agents search by intent (for example 'send an sms' or 'send a survey') and Jentic returns the matching Esendex operation plus its parameter schema, so the agent picks the right endpoint without parsing both auth flavours.
Time to first call
Direct Esendex integration: 2-3 days to wire dual-auth, batch scheduling, webhook subscription, and survey reporting. Through Jentic: under 1 hour — search, load, execute.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Esendex API through Jentic.
Why is there no official OpenAPI spec for the Esendex API?
Esendex publishes developer documentation at developers.esendex.com but not a downloadable OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call the Esendex API 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 Esendex API use?
The Esendex API supports two schemes: HTTP Basic for the legacy SMS endpoints and an apiKey Authorization header for newer rich-content and survey routes. Through Jentic both are stored encrypted in the MAXsystem vault and injected at execution time.
Can I send an SMS with the Esendex API?
Yes. POST /messagedispatcher accepts one or many message objects (recipient, body, account reference) and returns delivery batch metadata. Read GET /messageheaders/{id} to track per-message state.
What are the rate limits for the Esendex API?
Esendex applies per-account throughput controls based on your plan but does not encode them in the spec. Submit large sends as batches via /messagedispatcher rather than tight per-message loops, and respect 429 backoff.
How do I send a rich-content message through Jentic?
Search 'send rich content message'. Jentic returns the POST /send operation, you load its schema, and execute with the recipient and content payload. The Authorization API key is injected from the vault.
Can I read a conversation thread by phone number?
Yes. GET /conversation/{phonenumber}/messages returns the chronological message history for that number across both directions, useful for a unified inbox UI.
Does the API support webhook subscriptions for inbound messages?
Yes. POST /accounts/{accountReference}/subscriptions creates a webhook subscription scoped to an account, and DELETE /accounts/{accountReference}/subscriptions/{productId}/{eventId} removes one.
GET STARTED