> ## Documentation Index
> Fetch the complete documentation index at: https://hellotars.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Send channel messages API
> Send an outbound message on a connected channel with the POST /api/channels/send endpoint.
export const img = {
activity: {
activityTimeline: "/docs/guides/activity/images/activity-timeline.png",
capturedVariablesPanel: "/docs/guides/activity/images/captured-variables-panel.png",
dataViewCards: "/docs/guides/activity/images/data-view-cards.png",
exportDataDialog: "/docs/guides/activity/images/export-data-dialog.png",
tasksPanelExportReady: "/docs/guides/activity/images/tasks-panel-export-ready.png"
},
analytics: {
analyticsOverview: "/docs/guides/analytics/images/analytics-overview.png",
exploreGallery: "/docs/guides/analytics/images/explore-gallery.png",
exploreTab: "/docs/guides/analytics/images/explore-tab.png",
goalForm: "/docs/guides/analytics/images/goal-form.png",
goalsTab: "/docs/guides/analytics/images/goals-tab.png",
improveDiagnostics: "/docs/guides/analytics/images/improve-diagnostics.png",
improveTab: "/docs/guides/analytics/images/improve-tab.png",
teamTab: "/docs/guides/analytics/images/team-tab.png"
},
billing: {
billingOverview: "/docs/guides/billing/images/billing-overview.png",
buyConversationsDialog: "/docs/guides/billing/images/buy-conversations-dialog.png",
buySeatsDialog: "/docs/guides/billing/images/buy-seats-dialog.png",
livechatSeatsTab: "/docs/guides/billing/images/livechat-seats-tab.png",
organizationDeletionLifecycle: "/docs/guides/billing/images/organization-deletion-lifecycle.svg",
organizationSwitcher: "/docs/guides/billing/images/organization-switcher.png",
rolesAndAccessMatrix: "/docs/guides/billing/images/roles-and-access-matrix.png"
},
building: {
agentBehaviorGuardrails: "/docs/guides/building/images/agent-behavior-guardrails.png",
agentCardMenu: "/docs/guides/building/images/agent-card-menu.png",
agentConfigure: "/docs/guides/building/images/agent-configure.png",
agentExitRoutesDialog: "/docs/guides/building/images/agent-exit-routes-dialog.png",
agentLibrary: "/docs/guides/building/images/agent-library.png",
agentModelParameters: "/docs/guides/building/images/agent-model-parameters.png",
aiAgentGambitLoop: "/docs/guides/building/images/ai-agent-gambit-loop.svg",
builderBasics: "/docs/guides/building/images/builder-basics.png",
builderConnectHandlePanel: "/docs/guides/building/images/builder-connect-handle-panel.png",
builtInToolsDialog: "/docs/guides/building/images/built-in-tools-dialog.png",
configureDebugTab: "/docs/guides/building/images/configure-debug-tab.png",
configureLanguage: "/docs/guides/building/images/configure-language.png",
configureNotifications: "/docs/guides/building/images/configure-notifications.png",
createAgentDialog: "/docs/guides/building/images/create-agent-dialog.png",
draftPublishRollbackPinning: "/docs/guides/building/images/draft-publish-rollback-pinning.svg",
draftSwitcherChip: "/docs/guides/building/images/draft-switcher-chip.png",
duplicateAgentDialog: "/docs/guides/building/images/duplicate-agent-dialog.png",
flowConditions: "/docs/guides/building/images/flow-conditions.png",
gambitPalette: "/docs/guides/building/images/gambit-palette.png",
gambits: {
gambitAiAgent: "/docs/guides/building/gambits/images/gambit-ai-agent.png",
gambitApiCall: "/docs/guides/building/gambits/images/gambit-api-call.png",
gambitAutoSuggestion: "/docs/guides/building/gambits/images/gambit-auto-suggestion.png",
gambitButton: "/docs/guides/building/gambits/images/gambit-button.png",
gambitCard: "/docs/guides/building/gambits/images/gambit-card.png",
gambitChannel: "/docs/guides/building/gambits/images/gambit-channel.png",
gambitCustomCode: "/docs/guides/building/gambits/images/gambit-custom-code.png",
gambitDateTime: "/docs/guides/building/gambits/images/gambit-date-time.png",
gambitGeoLocation: "/docs/guides/building/gambits/images/gambit-geo-location.png",
gambitLanguage: "/docs/guides/building/gambits/images/gambit-language.png",
gambitLiveChat: "/docs/guides/building/gambits/images/gambit-live-chat.png",
gambitMediaUpload: "/docs/guides/building/gambits/images/gambit-media-upload.png",
gambitNoInput: "/docs/guides/building/gambits/images/gambit-no-input.png",
gambitRedirect: "/docs/guides/building/gambits/images/gambit-redirect.png",
gambitStarRating: "/docs/guides/building/gambits/images/gambit-star-rating.png",
gambitStartAndEnd: "/docs/guides/building/gambits/images/gambit-start-and-end.png",
gambitText: "/docs/guides/building/gambits/images/gambit-text.png",
gambitTrigger: "/docs/guides/building/gambits/images/gambit-trigger.png"
},
languagesTranslateGambit: "/docs/guides/building/images/languages-translate-gambit.png",
languageSystemMessages: "/docs/guides/building/images/language-system-messages.png",
newDraftDialog: "/docs/guides/building/images/new-draft-dialog.png",
outputComponentsGrid: "/docs/guides/building/images/output-components-grid.png",
publishDialog: "/docs/guides/building/images/publish-dialog.png",
systemPromptDialog: "/docs/guides/building/images/system-prompt-dialog.png",
testModeEventLog: "/docs/guides/building/images/test-mode-event-log.png",
testModePanel: "/docs/guides/building/images/test-mode-panel.png",
validationProblemsPanel: "/docs/guides/building/images/validation-problems-panel.png",
variablePickerPanel: "/docs/guides/building/images/variable-picker-panel.png",
variablePillInserted: "/docs/guides/building/images/variable-pill-inserted.png",
versionsDraftsPanel: "/docs/guides/building/images/versions-drafts-panel.png"
},
campaigns: {
campaignFlavorsTriggers: "/docs/guides/campaigns/images/campaign-flavors-triggers.svg",
campaignReplyRouting: "/docs/guides/campaigns/images/campaign-reply-routing.svg",
campaignSendAnatomy: "/docs/guides/campaigns/images/campaign-send-anatomy.svg",
createACampaign: "/docs/guides/campaigns/images/create-a-campaign.png",
walletReserveSettleRefund: "/docs/guides/campaigns/images/wallet-reserve-settle-refund.svg",
webhookCampaignContractLocking: "/docs/guides/campaigns/images/webhook-campaign-contract-locking.svg",
webhookCampaignLifecycleStates: "/docs/guides/campaigns/images/webhook-campaign-lifecycle-states.svg",
webhookCampaignOneCallOneDelivery: "/docs/guides/campaigns/images/webhook-campaign-one-call-one-delivery.svg"
},
channels: {
distributeWhatsappConnect: "/docs/guides/channels/images/distribute-whatsapp-connect.png",
whatsappConnectDialogWaiting: "/docs/guides/channels/images/whatsapp-connect-dialog-waiting.png",
whatsappEmptyState: "/docs/guides/channels/images/whatsapp-empty-state.png"
},
deploy: {
bridgeEventGambitSection: "/docs/guides/deploy/images/bridge-event-gambit-section.png",
deploymentSurfacesAndChannels: "/docs/guides/deploy/images/deployment-surfaces-and-channels.svg",
designAgentTab: "/docs/guides/deploy/images/design-agent-tab.png",
designLauncherTab: "/docs/guides/deploy/images/design-launcher-tab.png",
embedIframeTab: "/docs/guides/deploy/images/embed-iframe-tab.png",
embedTheWidget: "/docs/guides/deploy/images/embed-the-widget.png",
mobileAppIntegration: "/docs/guides/deploy/images/mobile-app-integration.png",
onYourDomain: "/docs/guides/deploy/images/on-your-domain.png",
shareYourAgentLink: "/docs/guides/deploy/images/share-your-agent-link.png"
},
developer: {
api: {
channelSendTemplateVsMessage: "/docs/developer/api/images/channel-send-template-vs-message.svg",
endUsers: {
endUsersListCursorPagination: "/docs/developer/api/end-users/images/end-users-list-cursor-pagination.svg"
},
triggerCallConversationLifecycle: "/docs/developer/api/images/trigger-call-conversation-lifecycle.svg"
},
developerSurfacesMap: "/docs/developer/images/developer-surfaces-map.svg",
embed: {
embedConfigToWidgetContext: "/docs/developer/embed/images/embed-config-to-widget-context.svg",
hostPageBridgeFlow: "/docs/developer/embed/images/host-page-bridge-flow.svg",
identitySigningFlow: "/docs/developer/embed/images/identity-signing-flow.svg",
scriptVsIframeEmbed: "/docs/developer/embed/images/script-vs-iframe-embed.svg"
},
mobile: {
bridgeMessageProtocol: "/docs/developer/mobile/images/bridge-message-protocol.svg",
webviewBridgeArchitecture: "/docs/developer/mobile/images/webview-bridge-architecture.svg"
}
},
endUsers: {
anonymousToIdentifiedProfile: "/docs/guides/end-users/images/anonymous-to-identified-profile.svg",
bulkActionBar: "/docs/guides/end-users/images/bulk-action-bar.png",
campaignConsentGate: "/docs/guides/end-users/images/campaign-consent-gate.svg",
consentPerChannelStates: "/docs/guides/end-users/images/consent-per-channel-states.svg",
dynamicVsStaticSegments: "/docs/guides/end-users/images/dynamic-vs-static-segments.svg",
endUserDirectory: "/docs/guides/end-users/images/end-user-directory.png",
endUserProfileAcrossChannels: "/docs/guides/end-users/images/end-user-profile-across-channels.svg",
endUserProfilePanes: "/docs/guides/end-users/images/end-user-profile-panes.png",
profileMergeAndTakeoverProtection: "/docs/guides/end-users/images/profile-merge-and-takeover-protection.svg",
segmentBuilder: "/docs/guides/end-users/images/segment-builder.png",
segmentsPage: "/docs/guides/end-users/images/segments-page.png"
},
getStarted: {
agentStates: "/docs/get-started/images/agent-states.svg",
buildToLivePath: "/docs/get-started/images/build-to-live-path.svg",
dashboardSidebarMap: "/docs/get-started/images/dashboard-sidebar-map.png",
organizationOwnershipAndRoles: "/docs/get-started/images/organization-ownership-and-roles.svg",
quickstart: {
step1CreateYourAccount: "/docs/get-started/images/quickstart/step-1-create-your-account.png",
step3ConnectTheAiAgent: "/docs/get-started/images/quickstart/step-3-connect-the-ai-agent.png",
step4TestMode: "/docs/get-started/images/quickstart/step-4-test-mode.png"
},
quickstartCanvas: "/docs/get-started/images/quickstart-canvas.png"
},
knowledge: {
addASource: "/docs/guides/knowledge/images/add-a-source.png",
addRetrieverPicker: "/docs/guides/knowledge/images/add-retriever-picker.png",
attachKnowledgeGambit: "/docs/guides/knowledge/images/attach-knowledge-gambit.png",
configureARetriever: "/docs/guides/knowledge/images/configure-a-retriever.png",
createKnowledgeBaseDialog: "/docs/guides/knowledge/images/create-knowledge-base-dialog.png",
customRetrieverDialog: "/docs/guides/knowledge/images/custom-retriever-dialog.png",
datasetTab: "/docs/guides/knowledge/images/dataset-tab.png",
documentChangeReindexLifecycle: "/docs/guides/knowledge/images/document-change-reindex-lifecycle.svg",
documentsTabPreview: "/docs/guides/knowledge/images/documents-tab-preview.png",
importAWebsite: "/docs/guides/knowledge/images/import-a-website.png",
kbList: "/docs/guides/knowledge/images/kb-list.png",
retrieverIndexStates: "/docs/guides/knowledge/images/retriever-index-states.svg",
retrieverQueryPipeline: "/docs/guides/knowledge/images/retriever-query-pipeline.svg",
standardVsParentChildChunking: "/docs/guides/knowledge/images/standard-vs-parent-child-chunking.svg",
syncManagement: "/docs/guides/knowledge/images/sync-management.png",
testRetriever: "/docs/guides/knowledge/images/test-retriever.png"
},
liveChat: {
agentWorkspace: "/docs/guides/live-chat/images/agent-workspace.png",
assignedAgentPicker: "/docs/guides/live-chat/images/assigned-agent-picker.png",
automaticAssignmentRouting: "/docs/guides/live-chat/images/automatic-assignment-routing.svg",
availabilityDropdown: "/docs/guides/live-chat/images/availability-dropdown.png",
cannedResponses: "/docs/guides/live-chat/images/canned-responses.png",
composerPreferences: "/docs/guides/live-chat/images/composer-preferences.png",
copilotPanel: "/docs/guides/live-chat/images/copilot-panel.png",
filterConversationsDialog: "/docs/guides/live-chat/images/filter-conversations-dialog.png",
inboxAnalyticsTab: "/docs/guides/live-chat/images/inbox-analytics-tab.png",
inboxAvailabilityTab: "/docs/guides/live-chat/images/inbox-availability-tab.png",
inboxesSettings: "/docs/guides/live-chat/images/inboxes-settings.png",
inboxRoutingTab: "/docs/guides/live-chat/images/inbox-routing-tab.png",
labelsSettings: "/docs/guides/live-chat/images/labels-settings.png",
newAttributeDialog: "/docs/guides/live-chat/images/new-attribute-dialog.png",
newCannedResponseDialog: "/docs/guides/live-chat/images/new-canned-response-dialog.png",
notificationPreferences: "/docs/guides/live-chat/images/notification-preferences.png",
notificationsPage: "/docs/guides/live-chat/images/notifications-page.png",
pickupTargetCard: "/docs/guides/live-chat/images/pickup-target-card.png",
resolveMenu: "/docs/guides/live-chat/images/resolve-menu.png",
searchDialog: "/docs/guides/live-chat/images/search-dialog.png",
seatGateConversation: "/docs/guides/live-chat/images/seat-gate-conversation.png",
seatsSettings: "/docs/guides/live-chat/images/seats-settings.png",
workTheInbox: "/docs/guides/live-chat/images/work-the-inbox.png"
},
security: {
addOpenRouterKeyDialog: "/docs/guides/security/images/add-open-router-key-dialog.png",
auditChainVerified: "/docs/guides/security/images/audit-chain-verified.png",
auditEventDrawer: "/docs/guides/security/images/audit-event-drawer.png",
auditExportDialog: "/docs/guides/security/images/audit-export-dialog.png",
auditLogViewer: "/docs/guides/security/images/audit-log-viewer.png",
auditRecordLifecycle: "/docs/guides/security/images/audit-record-lifecycle.svg",
logPrivacyRedactionEnabled: "/docs/guides/security/images/log-privacy-redaction-enabled.png",
modelProviderEmptyState: "/docs/guides/security/images/model-provider-empty-state.png",
privacySettings: "/docs/guides/security/images/privacy-settings.png",
siemConnectWizard: "/docs/guides/security/images/siem-connect-wizard.png",
supportActorMasking: "/docs/guides/security/images/support-actor-masking.svg"
},
tools: {
addToolModal: "/docs/guides/tools/images/add-tool-modal.png",
addToolsPanel: "/docs/guides/tools/images/add-tools-panel.png",
codekitActionEditor: "/docs/guides/tools/images/codekit-action-editor.png",
codekitConnectToolkitsDialog: "/docs/guides/tools/images/codekit-connect-toolkits-dialog.png",
codekitSchemaDialog: "/docs/guides/tools/images/codekit-schema-dialog.png",
codekitToolkit: "/docs/guides/tools/images/codekit-toolkit.png",
codekitToolkitAnatomy: "/docs/guides/tools/images/codekit-toolkit-anatomy.svg",
createActionDialog: "/docs/guides/tools/images/create-action-dialog.png",
createCodekitDialog: "/docs/guides/tools/images/create-codekit-dialog.png",
responseFilteringDialog: "/docs/guides/tools/images/response-filtering-dialog.png",
toolGambitEditorAgentMode: "/docs/guides/tools/images/tool-gambit-editor-agent-mode.png",
toolGambitEditorWorkflowMode: "/docs/guides/tools/images/tool-gambit-editor-workflow-mode.png",
toolkitDetail: "/docs/guides/tools/images/toolkit-detail.png",
toolsConnected: "/docs/guides/tools/images/tools-connected.png",
toolsDirectory: "/docs/guides/tools/images/tools-directory.png",
viewActionsModal: "/docs/guides/tools/images/view-actions-modal.png",
workflowModeResponse: "/docs/guides/tools/images/workflow-mode-response.png"
}
};
The message goes out from the WhatsApp number assigned to the target agent, so that agent needs a connected number first. A plain `message` send works only inside an open messaging window. Use `template` for out-of-window messages.
## Request
`Bearer YOUR_API_KEY`, a key with the **Channels** permission.
`whatsapp`. Any other value fails with a `400`.
The recipient's channel identifier. For WhatsApp, the phone number in international format.
`template` or `message`.
The target agent's public ID. Required for organization keys. Agent-scoped keys default to their own agent.
The approved template to send. Required with `type: "template"`.
The approved template's name.
The template's language code, for example `en_US`.
`body` and `header` arrays of strings, in positional order.
`{ "text": "…" }`, a plain text message. Required with `type: "message"`.
```bash cURL theme={null}
curl -X POST \
https://us.api.hellotars.com/api/channels/send \
-H 'Authorization: Bearer YOUR_API_KEY' \
-H 'Content-Type: application/json' \
-d '{
"channel": "whatsapp",
"to": "+15551234567",
"type": "template",
"convId": "YOUR_AGENT_ID",
"template": {
"name": "order_update",
"language": "en_US",
"parameters": { "body": ["A-1042", "shipped"] }
}
}'
```
```javascript JavaScript theme={null}
const response = await fetch(
"https://us.api.hellotars.com/api/channels/send",
{
method: "POST",
headers: {
Authorization: `Bearer ${process.env.TARS_API_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
channel: "whatsapp",
to: "+15551234567",
type: "template",
convId: "YOUR_AGENT_ID",
template: {
name: "order_update",
language: "en_US",
parameters: { body: ["A-1042", "shipped"] }
}
})
}
);
const data = await response.json();
```
```python Python theme={null}
import os
import requests
response = requests.post(
"https://us.api.hellotars.com/api/channels/send",
headers={
"Authorization": f"Bearer {os.environ['TARS_API_KEY']}",
"Content-Type": "application/json",
},
json={
"channel": "whatsapp",
"to": "+15551234567",
"type": "template",
"convId": "YOUR_AGENT_ID",
"template": {
"name": "order_update",
"language": "en_US",
"parameters": {"body": ["A-1042", "shipped"]},
},
},
)
data = response.json()
```
## Response
`true` on a successful send.
`template` or `message`, echoing the send type.
The channel the message was sent on.
The provider's message ID when the provider returns one.
```json 200 theme={null}
{
"success": true,
"messageType": "template",
"channel": "whatsapp",
"messageId": "PROVIDER_MESSAGE_ID"
}
```
## Errors
Error responses return `{ "success": false, "error": "…" }` with one of these statuses.
| Status | Cause |
| ------ | ----------------------------------------------------------------------------------------------------------------- |
| `400` | Missing or invalid body fields, no WhatsApp number assigned to the agent, or an organization key without `convId` |
| `400` | A `type` sent without its matching `template` or `message` object |
| `400` | The provider rejected the send |
| `401` | Missing `Authorization` header, or an invalid or revoked key |
| `403` | Key not authorized for this agent, or the key lacks the **Channels** permission |
| `404` | No agent in your organization matches `convId` |
| `429` | Rate limit exceeded. Retry after the `Retry-After: 60` header elapses |
## Related pages
* [API authentication](/docs/developer/authentication)
* [Start conversations API](/docs/developer/api/start-conversations)
* [Channels overview](/docs/guides/channels/channels-overview)
## OpenAPI
````yaml api-reference/openapi.json POST /api/channels/send
openapi: 3.1.0
info:
title: Tars API
version: 3.0.0
description: >-
Public REST API for Tars agents: start conversations at trigger gambits,
send channel messages, manage end users, and drive webhook campaigns.
servers:
- url: https://us.api.hellotars.com
description: United States
- url: https://eu.api.hellotars.com
description: European Union
- url: https://in.api.hellotars.com
description: India
- url: https://qa.api.hellotars.com
description: Qatar
security:
- bearerAuth: []
tags:
- name: Triggers
description: Start conversations at trigger gambits
- name: Channels
description: Outbound channel message sends
- name: End users
description: End-user record management
- name: Campaigns
description: Webhook campaign sends and validation
paths:
/api/channels/send:
post:
tags:
- Channels
summary: Send an outbound message on a connected channel
operationId: sendChannelMessage
requestBody:
required: true
content:
application/json:
schema:
type: object
properties:
channel:
type: string
enum:
- whatsapp
description: >-
The channel to send on. Only whatsapp can deliver today, and
every other value is rejected.
to:
type: string
description: >-
The recipient's channel identifier. For WhatsApp, the phone
number in international format.
type:
type: string
enum:
- template
- message
description: >-
Send an approved template, or a plain text message inside an
open messaging window. Use template outside the window.
convId:
type: string
description: >-
Target agent's public ID. Required for organization keys,
and defaulted for agent-scoped keys.
template:
type: object
description: >-
The approved template to send. Required when type is
template.
properties:
name:
type: string
description: The approved template's name.
language:
type: string
description: The template's language code, for example en_US.
parameters:
type: object
description: >-
body and header arrays of strings, in the order the
template expects them.
required:
- name
- language
message:
type: object
description: A plain text message. Required when type is message.
properties:
text:
type: string
description: The message body.
required:
- text
required:
- channel
- to
- type
responses:
'200':
description: Message sent
content:
application/json:
schema:
type: object
properties:
success:
type: boolean
description: True when the channel accepted the message.
messageType:
type: string
enum:
- template
- message
description: Echoes the send type from the request.
channel:
type: string
description: The channel the message went out on.
messageId:
type: string
description: >-
The provider's message ID, when the provider returned one.
Use it to match delivery webhooks.
required:
- success
'400':
description: >-
Missing or invalid body fields, an organization key without convId,
or a send the channel could not complete, such as no channel account
assigned to the agent or a provider rejection
content:
application/json:
schema:
$ref: '#/components/schemas/ApiError'
'401':
description: Missing, invalid, or revoked API key
content:
application/json:
schema:
$ref: '#/components/schemas/ApiError'
'403':
description: Key not authorized for this agent, or lacks the Channels permission
content:
application/json:
schema:
$ref: '#/components/schemas/ApiError'
'404':
description: No agent matches convId
content:
application/json:
schema:
$ref: '#/components/schemas/ApiError'
'429':
description: Rate limit exceeded
headers:
Retry-After:
description: Seconds to wait before retrying
schema:
type: string
content:
application/json:
schema:
$ref: '#/components/schemas/ApiError'
components:
schemas:
ApiError:
type: object
description: An error from the trigger and channel endpoints.
properties:
success:
type: boolean
const: false
description: Always false on an error response.
error:
type: string
description: A sentence describing what went wrong.
required:
- success
- error
securitySchemes:
bearerAuth:
type: http
scheme: bearer
description: >-
API key sent as Authorization: Bearer YOUR_API_KEY. Campaign endpoints
use campaign-scoped keys; the rest use organization or agent keys with
the matching permission.
````