Retell AI · Rate Limits

Retell Ai Rate Limits

Retell rate-limits primarily through concurrent call entitlements: 20 free concurrent calls with each additional concurrency slot priced at $8/month. Knowledge bases get the first 10 free. Per-RPS HTTP rate limits are not publicly documented.

Retell Ai Rate Limits is the machine-readable rate-limit profile for Retell AI on the APIs.io network, in the API Commons Rate Limits shape.

It captures 4 rate-limit definitions, measuring concurrent_calls, knowledge_bases, and requests.

An exhausted limit returns HTTP 429.

This profile was written by API Evangelist and has not been verified against a page the provider published; treat every limit as unconfirmed until a dated transcription replaces it.

The profile also includes 2 backoff/retry policies defined and response codes documented for throttled.

Tagged areas include AI, Voice, Agents, Realtime, and Conversational.

4 Limits Exhausted: HTTP 429
Method: generated, dated 2026-05-08.
Written by API Evangelist on 2026-05-08 and not verified against a page the provider published. Treat every limit as unconfirmed until a dated transcription replaces it.
View Source
AIVoiceAgentsRealtimeConversationalRate LimitingQuotasThrottling

Limits

Concurrent Calls (free tier) account
concurrent_calls
20
20 free concurrent calls included by default.
Concurrent Calls (add-on) account
concurrent_calls
-1
Additional concurrency at $8.00/concurrency/month.
Knowledge Bases (free) account
knowledge_bases
10
First 10 knowledge bases free.
HTTP Requests account
requests
not publicly documented
Verify with Retell support; standard 429 backoff applies.

Policies

Backoff Strategy
Clients should implement exponential backoff with jitter and honor any Retry-After header.
Concurrency Provisioning
Pre-purchase concurrency slots ahead of high-volume campaigns to avoid throttling.

Sources

Work with this as data

Every rate limit here is available over the APIs.io API and to AI agents over MCP.

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Tools for rate limits

4 MCP tools reach this
  • find_rate_limitsBrowse and filter every rate limit in the catalog.
  • apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
  • resolveTurn a domain, URL or GitHub org into the provider it belongs to.
  • find_cohortsEvery scored population of providers in the catalog.
All 92 tools →

Call it yourself

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All rate limits 
curl "https://apis.io/api/v1/rate-limits?limit=25"

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