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The Trackly SMS API allows you to send SMS messages programmatically. Use it to integrate SMS into your applications, automate sends from your systems, or build custom integrations.

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Base URL

All API requests should be made to: 
https://app.tracklysms.com/api

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API Versions

The v1 API is deprecated. All v1 endpoints will continue to work but include deprecation headers in responses. Please migrate to v2 as soon as possible.
VersionStatusNotes
v1DeprecatedLegacy API, includes deprecation headers
v2CurrentProduction API with enhanced endpoints and features

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Authentication

All API requests require authentication using an API key passed in the X-Api-Key header. 
curl -X POST https://app.tracklysms.com/api/v2/send \
  -H "X-Api-Key: trk_your_api_key_here" \
  -H "Content-Type: application/json" \
  -d '{"to": "+14155551234", "body": "Hello!", "list_number": "+18005551234"}'
The v2 API uses to for the recipient phone number and list_number for the sending phone number (E.164 format).
See Authentication for details on obtaining and managing API keys.

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V2 API (Current)

The v2 API is the current, recommended version with full support for contacts, audiences, creatives, schedules, revenue tracking, and more. View V2 API Reference

V2 API Overview

Full v2 API reference with all endpoints

Send Messages

Send single and bulk SMS messages

Contacts

Create, list, and manage contacts

Audiences

Build dynamic audience segments

Schedules

Schedule and automate campaigns

Migration Guide

Upgrade from v1 to v2

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V1 API (Deprecated)

Messages (v1)

Send messages (deprecated)

Contacts (v1)

Contact stubs (no-op)

Webhooks

Delivery status webhooks

Error Codes

V1 error reference

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Request Format

  • All requests must include Content-Type: application/json
  • Phone numbers should be in E.164 format (e.g., +14155551234)
  • Request bodies must be valid JSON

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Response Format

All responses are JSON with a consistent structure: 
{
  "success": true,
  "message_id": "AbC12345",
  "status": "queued"
}

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Deprecation Headers

All v1 API responses include these headers:
HeaderValue
X-API-Deprecatedv1 is deprecated
Deprecationtrue

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API Limits

Trackly SMS does not impose API rate limits. The platform supports up to 50 million messages per minute. See API Limits & Best Practices for payload size limits and batch guidance.

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SDKs & Libraries

Currently, we recommend using standard HTTP libraries in your preferred language: 
curl -X POST https://app.tracklysms.com/api/v2/send \
  -H "X-Api-Key: trk_your_api_key_here" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "+14155551234",
    "body": "Hello from Trackly!",
    "list_number": "+18005551234"
  }'

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Next Steps

Send First SMS

Get started with a quick tutorial

V2 API Overview

Explore the full v2 API