Plan Limits
Each subscription plan includes a monthly character allowance and request rate limit. Usage resets at the start of each billing period.
- Starter — 10,000 chars/month, 10 req/min. Free tier, no credit card required.
- Pro — 500,000 chars/month, 60 req/min. $29/month.
- Scale — 2,000,000 chars/month, 120 req/min. $99/month.
- Enterprise — Custom limits and rate. Contact sales.
Check Usage
Check your current usage against plan limits. Returns characters used, remaining quota, and rate limit status.
/api/user/usageAUTHGet current usage statistics.
Response
{
"plan": "pro",
"period_start": "2026-02-01T00:00:00Z",
"period_end": "2026-03-01T00:00:00Z",
"characters": {
"used": 125000,
"limit": 500000,
"remaining": 375000
},
"requests": {
"rate_limit": 60,
"current_minute": 12
},
"api_keys": {
"active": 2,
"max": 10
}
}Rate Limiting
Rate limits are applied per API key on a per-minute basis. When you exceed your rate limit, the API returns 429 Too Many Requests with a Retry-After header.
Rate limit headers are included in every response so you can track your usage proactively.
- X-RateLimit-Limit — Your plan's requests-per-minute limit.
- X-RateLimit-Remaining — Requests remaining in the current window.
- X-RateLimit-Reset — Unix timestamp when the window resets.
- Retry-After — Seconds to wait before retrying (only on 429 responses).
Rate limit response headers
X-RateLimit-Limit: 60
X-RateLimit-Remaining: 48
X-RateLimit-Reset: 1707307200
Retry-After: 30Character Metering
Characters are metered at the time of synthesis. The character count is based on the input text length after normalization (whitespace trimming, unicode normalization). SSML tags are not counted.
If a synthesis request fails, the characters are not deducted from your quota.
API Key Limits
Each plan allows a maximum number of active API keys. Rate limits are per-key, so distributing requests across multiple keys does not bypass rate limits — the total is still enforced at the account level.
- Starter — 2 API keys max.
- Pro — 10 API keys max.
- Scale — 25 API keys max.
- Enterprise — Unlimited.