REST API for rewriting, scoring, and generating conversion-tuned email. Bearer-token auth. Rate-limited per workspace. Base URL: https://api.highconvertingemails.com. Version: 1.2.
All endpoints require a bearer token in the Authorization header. Mint a key from workspace settings. Keys are scoped to a workspace; rate limits apply per workspace, not per key.
Authorization: Bearer hce_pk_...All errors return JSON with `error`, `code`, and optional `details`. Common codes:
401 — missing or invalid bearer token.402 — plan quota exhausted; upgrade or buy credits.429 — rate limit exceeded; honor the `Retry-After` header.400 — invalid request body; check `details` for field-level errors./v1/rewriteGenerates 3 conversion-tuned variants of the draft with per-change rationale. Streams variant 1 token-by-token via SSE when `Accept: text/event-stream` is set.
/v1/subject-linesGenerates ranked subject lines with predicted open-rate scores, reasoning, and risk flags.
/v1/preheaderGenerates preheader text paired with a given subject. Returns synergy score per option.
/v1/ctaGenerates ranked CTA options with directness/urgency/friction sub-scores.
/v1/sequencesGenerates an N-step sequence with inter-step coherence. Async — returns a jobId; subscribe via webhook or poll for completion.
/v1/localizeCultural adaptation (not literal translation) across ES, FR, DE, PT-BR.
/v1/scoreComposite score across clarity, CTA strength, spam triggers, readability, persuasion structure, and AI-likeness. Returns inline annotations with character offsets.
/v1/roastHarsh-rubric feedback mode. Same JSON shape as /v1/score but tuned for direct critique.
/v1/teardownExtracts angle, hook, and structure from a competitor email and generates 3 counter-positioned drafts.
/v1/ab-predictPredicts which of two variants would win, with confidence and dimensional breakdown. Calibrated, not measured.
Mint a key in workspace settings; check the full schema in the OpenAPI spec; or pipe the spec into your favorite client generator.