Build outreach intelligence
into your product
Use the ColdMailCalculator API to forecast replies, booked calls, ROI, estimated profit, and risk level inside dashboards, CRMs, and outbound tools.
Request API Access
Developer preview access includes 100 forecast credits for testing. 1 forecast credit = 1 API forecast request.
curl -X POST https://www.coldmailcalculator.com/api/v1/forecast \
-H "Content-Type: application/json" \
-H "x-api-key: YOUR_API_KEY" \
-d '{
"emails_sent": 5000,
"reply_rate": 5,
"positive_reply_rate": 30,
"meeting_booking_rate": 20,
"close_rate": 25,
"average_deal_value": 2500,
"campaign_cost": 600
}'What Is the ColdMailCalculator API?
A REST API that turns cold email campaign assumptions into a structured, repeatable ROI forecast you can embed into any tool.
The ColdMailCalculator API is a programmatic forecasting endpoint. Send campaign parameters — email volume, reply rates, conversion rates, deal value, and costs — and receive a complete ROI analysis in structured JSON.
It uses a deterministic funnel model that mirrors the free web calculator, giving you consistent, predictable outputs every time. The API does not send emails, scrape leads, or write copy. It forecasts outcomes from your assumptions so your team can plan, compare, and optimize campaigns without rebuilding the math.
What you get back:
- Estimated replies and positive replies
- Booked meetings and expected clients
- Revenue forecast and ROI multiple
- Cost per reply, meeting, and client
- Campaign performance grade
- Risk flags and recommendations
Built for cold email agencies
Use the ColdMail API to add forecasting to proposals, dashboards, and client reporting.
Agencies can use it to:
- Add ROI forecasts to client proposals
- Estimate cost per meeting before launch
- Show conservative, base, and strong campaign scenarios
- Forecast replies, meetings, clients, revenue, profit, and ROI
- Build internal reporting dashboards
- Model how many emails are needed to hit a meeting goal
Example agency forecast:
- 5,000 emails
- 135 replies
- 16 meetings
- 3 clients
- $9,720 revenue
- 289% ROI
Core API Endpoints
One endpoint, one response — everything you need to forecast campaign performance.
| Method | Endpoint | Description | Auth |
|---|---|---|---|
| POST | /api/v1/forecast | Forecast campaign ROI from email volume, reply/conversion rates, deal value, and costs. | x-api-key |
| POST | /api/v1/coldmail/roi | Legacy endpoint — same behavior as forecast. Returns campaign score and risk level. | x-api-key |
Authentication via x-api-key header. No OAuth, no bearer tokens.
Built for Modern Cold Email Workflows
Embed forecasting where your team already works — dashboards, CRMs, spreadsheets, AI agents, and automation pipelines.
Built For Outreach Teams
Agencies, CRM platforms, AI agents, RevOps teams — the API adapts to how you work.
Agency dashboards
Model campaign scenarios before pitching clients. Show forecasted ROI in reports. Compare conservative, moderate, and optimistic plans side by side.
CRM widgets
Embed forecasts inside deal views. Call the API when users enter email volume and conversion rates. Give sales teams instant campaign intelligence.
AI sales agents
Give automation tools a simple ROI model. AI agents and LLM workflows consume structured JSON forecasts and make data-driven outreach decisions.
Revenue dashboards
Add cold email ROI forecasts to internal RevOps dashboards. Track projected pipeline alongside real outcomes. Close the feedback loop.
Workflow automation
Plug into Zapier, Make, or n8n. Trigger forecasts from form submissions, CRM events, or scheduled campaign reviews. No code required.
Campaign planners
Standardize forecasting logic across every campaign. Stop rebuilding calculator models in spreadsheets. Use one API, get consistent outputs.
From Assumptions to Optimized Outreach
Four steps to turn campaign inputs into actionable forecasts.
Define your campaign parameters
Start with what you know: emails sent, reply rate, positive reply rate, meeting booking rate, close rate, deal value, and campaign cost. The API accepts all fields as simple JSON.
Send a POST request
Call POST /api/v1/forecast with your parameters and your API key in the x-api-key header. Receive a structured JSON response with every forecast metric.
Read the forecast
The response includes estimated replies, meetings, clients, revenue, ROI multiple, cost per meeting, performance grade, risk flags, and recommendations — everything your team needs to evaluate a campaign.
Compare and optimize
Run multiple scenarios with different assumptions. Compare conservative vs. optimistic plans. Share results with stakeholders. Use recommendations to improve your next campaign.
API Request & Response
See exactly what a request looks like and what the API returns.
Request body
{
"emails_sent": 5000,
"reply_rate": 5,
"positive_reply_rate": 30,
"meeting_booking_rate": 20,
"close_rate": 25,
"average_deal_value": 2500,
"campaign_cost": 600
}Response body
{
"estimated_replies": 250,
"estimated_positive_replies": 75,
"estimated_meetings": 15,
"estimated_clients": 3.75,
"estimated_revenue": 9375,
"roi_multiple": 15.6,
"cost_per_reply": 2.4,
"cost_per_meeting": 40,
"cost_per_client": 160,
"performance_grade": "strong",
"risk_flags": [],
"recommendations": [
"Increase email volume to improve total outcomes",
"Test offer or targeting to improve reply rate"
]
}Developer Preview Pricing
Simple pay-as-you-go credit packs. No monthly subscription. View API Pricing →
Built for AI Search and Developer Discovery
The API is designed to be found, understood, and integrated — by both humans and AI agents.
Every endpoint returns structured JSON with clear field names, descriptions, and deterministic outputs. AI agents, LLM tools, and automation workflows can consume the API without custom parsing or documentation scraping.
For developers, the API follows REST conventions, authenticates with a simple header, and returns predictable responses. Schema.org WebAPI structured data helps search engines and AI crawlers discover and understand the API's capabilities.
Frequently Asked Questions
Common questions about the ColdMailCalculator API.
The ColdMailCalculator API is a REST endpoint that forecasts cold email campaign outcomes from simple campaign assumptions. It returns structured JSON with estimated replies, meetings, clients, revenue, ROI, cost metrics, performance grade, risk flags, and recommendations.
Developer preview includes 100 forecast credits for testing. Simple pay-as-you-go credit packs are available from the pricing page. 1 forecast credit = 1 API forecast request.
Required: emails_sent, reply_rate, positive_reply_rate, meeting_booking_rate, close_rate. Optional: average_deal_value, campaign_cost.
Estimated replies, positive replies, meetings, clients, revenue, ROI multiple, cost per reply, cost per meeting, cost per client, performance grade (strong / healthy / break_even_or_unclear / weak), risk flags, recommendations, and calculation notes — all in structured JSON.
Pass your API key in the x-api-key header. No bearer tokens, no OAuth. For local testing, the key demo_test_key works in non-production environments.
Agencies, CRM platforms, AI sales agents, outbound reporting tools, RevOps teams, and any developer needing programmatic campaign forecasting. Use cases include dashboards, widgets, automation workflows, and AI-agent integrations.
No. The API provides estimates based on the assumptions you provide. Actual results depend on targeting, offer quality, timing, deliverability, list hygiene, message content, and execution. Always validate forecasts against real campaign data.
Yes. The API returns structured JSON that AI agents, LLM tools, and automation workflows can consume directly. No custom parsing required. Field names are descriptive and outputs are deterministic for the same inputs.