Nexmo Messages API
Browse all Nexmo APIs63
AI ReadinessAI-Aware (B-)63/100
Agent-ready OpenAPI document · curated by JenticCommunicationsChat Messagingbasic, bearer1 EndpointsREST
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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.
1
Step 1: Jentic One Host machine
# On the machine that will host your Jentic One instance:
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fnexmo.com%2Fnexmo-messages-api" | sh2
Step 2: Agent machine
# On the machine where your agent runs (keep this separate from the instance):
curl -fsSL "https://jentic.com/install.sh?src=apis&api=%2Fapis%2Fnexmo.com%2Fnexmo-messages-api" | 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
Jentic AI Readiness Score
This API is usable in Jentic One now. Its AI-readiness score against Jentic's framework shows where it stands today and where improvements would make it even easier for agents to use.
M
Messages API
- AI-Aware (B-)63/100
50
Foundational Compliance80
Developer Experience & Jentic Compatibility52
AI-Readiness & Agent Experience94
Agent Usability43
Security100
AI DiscoverabilityPowered by JenticScoring Framework 1.0.0 | Scoring Engine 0.4.0
Show dimension breakdown
50
Foundational Compliance
Base layer of spec validity and structural soundness.
Grade: D+Signals: 4
97%
Lint Results
Aggregated quality score from linter diagnostics, weighted by severity.
100%
Resolution Completeness
Percentage of `$ref` references that resolve successfully.
0%
Specification Validity
Checks whether the API description parses successfully and conforms to its declared specification (e.g., OpenAPI).
2%
Structural Integrity
Structural correctness score based on schema issues using logarithmic dampening.
80
Developer Experience & Jentic Compatibility
Clarity, completeness, and ingestion readiness for developers and tooling.
Grade: ASignals: 4
46%
Example Density
How richly the API is illustrated with examples.
99%
Example Validity
Percentage of examples that conform to their schemas.
75%
Response Coverage
Percentage of operations with complete response definitions (success, client error, server error).
100%
Tooling Readiness
Health of API ingestion, bundling, and resolution within Jentic pipelines.
52
AI-Readiness & Agent Experience
Semantic breadth, depth, and agent comprehension for AI systems.
Grade: C-Signals: 4
60%
Description Coverage
Coverage of descriptions across API elements.
0%
Error Standardization
Coverage of RFC 9457 Problem Details for error responses.
100%
OperationId Quality
Coverage, uniqueness, and casing consistency of operationIds for AI inference.
50%
Summary Coverage
Coverage of summaries across operations/tags/info.
94
Agent Usability
Functional utility, complexity comfort, and AI orchestration readiness.
Grade: A+Signals: 1
94%
Complexity Comfort
Agent comfort level based on API operational and structural complexity.
43
Security
Trust, risk posture, and security compliance.
Grade: D-Signals: 1
42%
Authentication Strength
Average quality of security schemes based on authentication method strength (weakest link for OAuth2).
100
AI Discoverability
Findability, semantic richness, and reasoning readiness.
Grade: A+Signals: 1
100%
Descriptive Richness
Clarity and depth of descriptions across API elements.
Score it yourself
Every API in the directory is allowlisted, so you can re-score it with no key required.
npx @jentic/api-scorecard-cli score <openapi-url>Why Jentic?
What agents get from Jentic-routed access to this vendor.
Setup
Wiring the Nexmo Messages API by hand means supporting both HTTP basic and JWT bearer auth, minting per-call JWTs from your Application signing key, and posting to the api.nexmo.com/v1/messages host with the correct channel-specific body. Through Jentic you install once, import the Messages API from the API Directory, store the credentials once, and your agent calls it.
Permission scoping
The Messages API exposes a single send endpoint and carries the channel and recipient in the request body, so scoping is by operation rather than by resource: limit the agent to the operation it needs, which is sending a single message on a supported channel. That send call is the only thing it can run.
Credential isolation
Your Nexmo basic credentials and Application signing key are stored once, encrypted, by your own Jentic One instance and used to mint per-call JWTs 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 message via Nexmo', and Jentic returns the POST / operation with its full request schema, including the channel-specific message_type variants for SMS, WhatsApp, Viber, and Messenger, so the agent calls the right endpoint without browsing the reference docs.
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 with Jentic One, the self-hosted execution layer.
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.
Can I limit what my agent is allowed to do with the Nexmo Messages API?
Yes. Because you run Jentic One yourself, your own rules decide which operations and credentials the agent may use, and the Nexmo Messages API exposes a single send endpoint (POST /) that carries the channel and recipient in the request body. You scope by operation: allow the agent only that one send call, so sending a message on a supported channel such as SMS, WhatsApp, Viber Service Message, or Messenger is the only thing it can do. Your Nexmo basic credentials and Application signing key stay stored by your instance and are used to mint per-call JWTs at execution time, so they never enter the agent's prompt or logs.
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