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Welcome to the ColdSend Public API! This API enables developers to programmatically create and manage cold email campaigns, configure sender accounts, manage domains, and track performance.
The ColdSend Public API follows REST principles with JSON request/response bodies, proper HTTP status codes, and comprehensive error handling.

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Key Capabilities

Campaign Management

Create, update, pause, and launch email campaigns with full lifecycle control.

Sender Accounts

Add and manage sender email accounts — ColdSend Native, Google Workspace, Microsoft 365, and custom SMTP.

Domain Management

Configure custom domains for professional email sending with automated DNS setup.

Lead Management

Upload leads via CSV, manage lead data, and track engagement metrics.

Granular Permissions

Secure your API with scope-based access control following the principle of least privilege.

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What You Can Build

Build tools that automatically create and launch campaigns based on triggers like form submissions, CRM updates, or scheduled events.
Use the /api/public/v1/campaigns endpoints to programmatically manage your entire campaign workflow.
Connect ColdSend to your existing tech stack: CRMs, marketing automation, data processing pipelines, and custom dashboards.
Automate onboarding by programmatically adding sender email accounts (ColdSend Native or SMTP).
Pull campaign performance data into your own analytics platforms or build custom dashboards.

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API Architecture

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Base URL

All API requests use the following base URL: 
https://api.coldsend.pro/api/public/v1

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Authentication

All endpoints require authentication via API key in the X-API-Key header: 
X-API-Key: cs_live_your_api_key_here
Learn more in the Authentication Overview.

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API Versioning

The current API version is v1: 
https://api.coldsend.pro/api/public/v1

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Error Handling

The API uses standard HTTP status codes:
StatusDescription
200 OKRequest succeeded
201 CreatedResource created
204 No ContentSucceeded with no body
400 Bad RequestInvalid request
401 UnauthorizedMissing or invalid API key
403 ForbiddenInsufficient scopes
404 Not FoundResource doesn’t exist
409 ConflictResource already exists
422 UnprocessableValidation error
429 Too Many RequestsRate limit exceeded

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Key Concepts

Campaigns progress through: DRAFT → ACTIVE → PAUSED → COMPLETED or FAILED.
Create campaigns in DRAFT, configure all components, then set launch: true to activate.
API keys use granular scopes. Follow the principle of least privilege — grant only the scopes your integration needs.Learn more in API Key Scopes.
Choose ColdSend Native for managed infrastructure (no SMTP config needed) or SMTP/BYOC for your own email accounts with custom credentials.Learn more in Sender Accounts Overview.
Up to 4 variants per campaign. Leads are randomly assigned by distribution percentage.Learn more in Email Variants.
Up to 3 follow-up steps with triggers like NOT_OPENED, NOT_REPLIED, and OPENED_BUT_NOT_REPLIED.Learn more in Follow-up Sequences.

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Resources

Quickstart

Get your first campaign up and running.

Reference

Error codes, rate limits, and API reference.

Authentication

API keys, scopes, and security.

Campaigns

Campaign creation, lifecycle, and management.

Sender Accounts

Configure sender email accounts.