The HighConvertingEmails API
Programmatic access to rewrite, score, subject lines, preheader, CTA, sequences, roast, teardown, A/B predict, and localize. Bearer-token auth. Rate-limited per workspace.
Use cases
CRM enrichment
Score every outbound email from your CRM before send. Surface inline annotations to reps as they compose. Block sends below a threshold score.
In-app email tooling
Wire rewrite, score, and subject-line generation into your own product's email composer. The API returns the same structured output our editor uses.
Agency tooling
Run sequences across many clients with brand-voice profiles per client. Generate, score, and refine programmatically from your own ops dashboard.
Authentication
Mint an API key from workspace settings. Pass it as a bearer token in the Authorization header. Keys are scoped to a workspace; rate limits apply per workspace, not per key.
curl -X POST https://api.highconvertingemails.com/v1/rewrite \
-H "Authorization: Bearer hce_pk_..." \
-H "Content-Type: application/json" \
-d '{"draft":"Hi there, hope all is well.","kind":"cold-outreach"}'Rate limits and pricing
- Free tier: 50 calls/day, 1 RPS. Soft-cap; we notify before hard-stopping.
- Pro tier ($49/month): 1,500 calls/month included; overage billed per call.
- Team tier ($129/month): 5,000 calls/month pooled across the workspace; overage at reduced per-call rate.
- Enterprise: custom limits and pricing. Contact us.
See the pricing page for the full breakdown.
Ready to integrate?
Full reference at /api/docs. The OpenAPI spec is available at /openapi.json.