Nexmo Messages API
Browse all Nexmo APIs★ Only Publicly Available OpenAPI DocumentCommunicationsChat Messagingbasic, bearer1 EndpointsREST
For Agents
Send a message over SMS, MMS, WhatsApp, Viber Service Message, or Facebook Messenger from a single POST endpoint that picks the channel via the request body.
Use for: Send a WhatsApp template message to a customer, Send a transactional SMS to a phone number, Send a Facebook Messenger image to a user, Trigger a Viber Service Message with text content
Not supported: Does not orchestrate multi-channel failover, register chat-app sender accounts, or expose inbound message webhooks — use only for sending a single message on one of the supported channels.
Jentic publishes the only available OpenAPI specification for Nexmo Messages API, keeping it validated and agent-ready. The Messages API is Nexmo's normalised cross-channel send endpoint: a single POST / accepts a request whose channel field selects SMS, MMS, WhatsApp, Viber Service Message, or Facebook Messenger. The same envelope carries the to/from fields and a channel-specific message_type (text, image, audio, video, file, template) so applications can reach a recipient on whichever channel they are reachable on without integrating each one separately.
Install Jentic One Beta
Connect the Nexmo Messages API to your agent
Jentic One is a self-hosted execution layer for AI agents. It lets your agent call the Nexmo Messages 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 Nexmo Messages API.
Send an SMS by setting channel=sms with text content via POST /
Send a WhatsApp text, image, audio, video, file, or template message by setting channel=whatsapp
Send a Viber Service Message via channel=viber_service
Send a Facebook Messenger message via channel=messenger
Send rich content (image, audio, video, file) by setting message_type appropriately for the chosen channel
Authenticate with either basic auth (api_key/api_secret) or a JWT bearer tied to a Nexmo application
Use Cases
Patterns agents use Nexmo Messages API for, with concrete tasks.
★ Cross-channel transactional messaging
E-commerce and SaaS teams send order confirmations, shipping updates, and OTPs over whichever channel each customer prefers. POST / takes the same envelope; only the channel and to fields change. The API returns 202 with a message_uuid that maps to delivery webhooks emitted by Nexmo.
POST / with channel=whatsapp, message_type=template, the recipient's number in to, the WhatsApp business number in from, and the template name and parameters in the body.
WhatsApp template send for marketing opt-ins
Customer engagement teams use WhatsApp's pre-approved templates to send opt-in invitations or notifications. The Messages API accepts the template name and namespace in the body and returns a 202 with a message_uuid, after which delivery and read events arrive on the configured webhook.
POST / with channel=whatsapp, message_type=template, and a template object containing name, namespace, and parameters.
Single-call cross-channel send for AI agents
An agent that needs to message a user can route by channel without integrating five APIs. Through Jentic, search for 'send a message via nexmo', load POST /, and execute with the right channel and message_type. Webhooks for delivery come back asynchronously to whatever URL the application registered with the Nexmo application.
Search Jentic for 'send a message via nexmo', load POST /, and execute with channel=sms, to, from, message_type=text, and text content.
Key Endpoints
1 endpoints — jentic publishes the only available openapi specification for nexmo messages api, keeping it validated and agent-ready.
METHOD
PATH
DESCRIPTION
POST
/
Send a message on the channel specified in the request body
POST
/
Send a message on the channel specified in the request body
Why Jentic?
Three things that make agents converge on Jentic-routed access.
Credential isolation
Nexmo basic credentials and application JWT signing keys are encrypted in the Jentic vault. Per-call JWTs are minted server-side and the chosen auth header is set at execution time, so the agent never holds the signing key.
Intent-based discovery
Agents search by intent (e.g., 'send a message via nexmo') and Jentic returns POST / with the full request schema, including the channel-specific message_type variants for SMS, WhatsApp, Viber, and Messenger.
Time to first call
Direct integration: 1-2 days for JWT signing, channel-specific bodies, and webhook handling. Through Jentic: under an hour — search, load, execute one send.
Related APIs
Alternatives and complements available in the Jentic catalogue.
FAQs
Specific to using Nexmo Messages API through Jentic.
Why is there no official OpenAPI spec for Nexmo Messages API?
Vonage (formerly Nexmo) does not publish an OpenAPI specification. Jentic generates and maintains this spec so that AI agents and developers can call Nexmo Messages 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 Nexmo Messages API use?
Either HTTP basic auth (api_key/api_secret) or HTTP bearer with an application-scoped JWT. For WhatsApp, Viber Service Message, and Messenger sends the JWT path is required because those channels are bound to a Nexmo application; SMS and MMS work with either.
Can I send WhatsApp template messages through this endpoint?
Yes. POST / with channel=whatsapp and message_type=template accepts the template name, namespace, and parameter array. The API returns 202 with a message_uuid and delivery and read events arrive at the application's configured webhook.
What are the rate limits for the Nexmo Messages API?
The OpenAPI spec does not declare rate limits. Per-channel limits apply: WhatsApp has business-tier quality ratings, Messenger applies Facebook's policy windows, and SMS has carrier-level throughput caps. Vonage publishes the per-channel details on developer.nexmo.com.
How do I send an SMS through Jentic?
Search Jentic for 'send a message via nexmo', load POST /, and execute with channel=sms, message_type=text, the recipient phone number in to, the sender id in from, and the message body in text.
How do I track delivery of a message I sent?
POST / returns a message_uuid in the 202 response. Status webhooks fire from Nexmo to the application's configured callback URL with that message_uuid and a status field (submitted, delivered, read, rejected) so the application can correlate.
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