Developer API

Cold email forecasting API

Run the same deterministic forecast engine used by the calculator inside your product, dashboard, or internal workflow.

Authentication

Send your one-time API key in the x-api-key header. Keys are stored only as hashes and can be revoked.

curl -X POST https://www.coldmailcalculator.com/api/v1/forecast \
+  -H "x-api-key: cmc_live_..." \
+  -H "content-type: application/json" \
+  -d '{"emailsSent":1000,"replyRate":5,"positiveReplyRate":40,"meetingBookingRate":50,"closeRate":20,"averageDealValue":3000}'

Responses and errors

Successful requests return forecast metrics and monthly usage. Invalid input returns 400, missing keys 401, inactive API plans 403, and exhausted usage 429.