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Some operations consume credits — the unit Brew meters AI generation and media rendering with. Each credit is worth $0.01 of underlying spend. Every credit-metered operation charges only on success. There are two metering modes:
  • Usage-metered — email generation, email import, AI email edits, semantic brand-image search, and image generation charge the actual model usage (token input/output for the email agent; embedding/image-gateway cost for search + image generation). The cost scales with the work, so there is no fixed number and no X-Credit-Cost header. The call still gates: an empty balance is rejected up front.
  • Fixed — every other media/render operation charges a flat, published per-operation cost, reported via the X-Credit-Cost response header.

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Which operations cost credits

OperationRouteMetering
Generate an emailPOST /v1/emailsUsage (tokens)
Import an email (HTML / MJML / JSX → editable design)POST /v1/emails/importUsage (tokens)
Edit an email (AI prompt edit)PATCH /v1/emails/{emailId}Usage (tokens)
Semantic brand-image searchGET /v1/brand/images?q=…Usage (embedding)
Generate an imagePOST /v1/content/generate-imageUsage (image)
Generate / animate a GIFPOST /v1/content/gif (from: "prompt" | "image" | "video")Fixed
Optimize / resize an imagePOST /v1/content/transform (operation: "optimize" | "resize")Fixed
Render HTML to a PNGPOST /v1/content/html-to-pngFixed
Add an image (saves to the brand image library)POST /v1/content/add-imageFixed
Everything else is free: all reads (including the no-q browse of GET /v1/brand/images), the deterministic JSX save branch of PATCH /v1/emails/{emailId} (a body with jsx instead of prompt), the accessibility audit (GET /v1/emails/{emailId}/accessibility-audit), and contact validation (POST /v1/contacts/validate). For fixed operations the cost is published and does not vary with output size — the authoritative number for a call is its X-Credit-Cost response header. For usage-metered operations the charge equals the real token/image cost the work incurred (no header). The full per-operation metering table is available machine-readably at GET /v1/help → credits.operations.

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Check your balance — GET /v1/usage

There is no dry-run cost preview. Credit-metered calls just charge on success; if you want to know what you can afford before you call, read your balance from the billing surface: 
curl "https://brew.new/api/v1/usage" \
  -H "Authorization: Bearer brew_…"

{
  "plan": "pro",
  "credits":    { "limit": 500, "used": 260, "remaining": 240 },
  "emailSends": { "limit": 50000, "used": 1200, "remaining": 48800 },
  "period":     { "start": "2026-06-01T00:00:00.000Z", "end": "2026-07-01T00:00:00.000Z" }
}
A null limit / remaining means unlimited. credits is the AI/media balance; emailSends is your monthly delivery allowance. Both reset at the period.end boundary. GET /v1/usage requires the emails scope.

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What a real (charged) call reports

A successful fixed-cost call charges the published cost exactly once and returns two headers:
HeaderMeaning
X-Credit-CostCredits charged for this call.
X-Credits-RemainingBalance after the charge.
Usage-metered calls (email generate/edit, image generation) bill the actual model usage to your account and do not return these headers — read your balance from GET /v1/usage before and after to see the delta. Charging is idempotent: a retry with the same Idempotency-Key replays the original response and is not charged again.

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Errors

CodeStatusWhen
INSUFFICIENT_CREDITS402Your balance is too low — below the fixed cost (fixed ops) or empty (usage-metered ops). details carries { cost, remaining, planKey }. Top up / upgrade — there’s no Retry-After because credits reset at the billing-period boundary (read it from GET /v1/usage’s period.end).
SERVICE_UNAVAILABLE503The credit balance could not be verified (a transient billing-backend outage). The gate fails closed — it refuses rather than do paid work it can’t meter. Retryable: a Retry-After header tells you when.
402 is a confirmed empty balance; 503 is “can’t check right now, try again shortly” — branch on the code, never on the message.

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