Skip to main content

​
Introduction

ColdSend provides a Public API for managing cold email campaigns programmatically. The API enables you to create campaigns, upload leads, configure sender accounts, and automate follow-up sequences.

​
What You Can Do

Campaign Management
  • Create and configure cold email campaigns
  • Upload leads with custom fields for personalization
  • Design A/B test variants for subject lines and content
  • Set up automated follow-up sequences
Sender Accounts
  • Connect your own email accounts (Google Workspace, Microsoft 365, or custom SMTP)
  • Manage daily sending limits per account
  • Validate connections before use
Automation
  • Schedule campaigns with timezone-aware sending windows
  • Trigger follow-ups based on recipient behavior
  • Track opens, replies, and bounces

​
API Architecture

The ColdSend API follows RESTful principles:
  • All endpoints use JSON for request and response bodies
  • Authentication is handled via API keys in the X-API-Key header
  • Base URL: https://api.coldsend.io
  • API version: /api/public/v1

​
Key Concepts

​
Campaigns

A campaign represents a single outreach effort. Each campaign contains:
  • Leads (recipients)
  • Email variants (for A/B testing)
  • Follow-up sequences
  • Sender accounts
Campaigns progress through a 5-step workflow before activation.

​
Leads

Leads are the recipients of your campaigns. Each lead has standard fields (email, name, company) and can have unlimited custom fields for personalization.

​
Variants

Variants allow A/B testing different email approaches. Each variant has its own subject line, content, and distribution percentage.

​
Sequences

Sequences define automated follow-up emails. Each sequence triggers based on conditions like “not opened” or “not replied” and sends after a configurable wait period.

​
Sender Accounts

Sender accounts are email addresses used to send campaigns. You can connect your own email accounts via SMTP/IMAP credentials.

​
Next Steps