Retell AI
Voice agents. Short-term context within call native; long-term memory via webhook integration to CRM / external DB. Cross-agent memory sharing in multi-agent setups.
Active · Verified 2026-10-22 · fresh as of 2026-10-22 · 45 cited facts, 4 with a third-party source · 1 recorded change · Suggest a correction
At a glance
- Type
- In-call + integration-based long-term vendor fix
- Tier
- T2
- Section
- Framework-embedded memory
- Latest release
- not applicable — not OSS fix
- License
- not applicable — not OSS fix
- GitHub
- not applicable — no GitHub repo fix
- Pricing
- Pay-as-you-go voice $0.07–0.31/min, chat from $0.002/msg, $10 free credits, 20 free concurrent calls (+$8/concurrent call/mo); Enterprise custom vendor fix
- Funding
- $5M total Seed · 2024-04 vendor fix
- Freshness
- 2026-10-22 fix
- Layer
- agent-infra repo fix
- Licensing
- commercial vendor fix
- SDK languages
- python, rest, typescript vendor fix
- Protocols
- mcp-client, mcp-server vendor fix
- Compliance
- ccpa, gdpr, hipaa, iso27001, soc2-type1, soc2-type2 vendor fix
Memory taxonomy
- storage
- kv
- retrieval
- injection
- persistence
- cross-session
- update
- overwrite
- unit
- episode
- governance
- inspectable
- conflict
- none
When to use
Optimised for: low-latency voice + integration-based long-term
Anti-fit: not for non-voice use cases
Pros & cons
Pros
Real-time voice agent platform with memory across calls — strong call-center workflow integration.
Cons
Voice-only; smaller mind-share than Vapi.
Claims & capabilities
Usage-based per minute. Free tier for testing.
Technical surface
- API surface
- searched not found
- Backend storage
- searched not found
- Deployment
- Managed-only (Retell-hosted; Enterprise dedicated-server add-on; no self-host option listed)
- Embedding model
- searched not found
- Multi-tenancy
- searched not found
- MCP
- yes — MCP Node lets agents call tools on external MCP servers mid-call
- A2A
- searched not found
- OpenTelemetry
- searched not found
Alternatives to Retell AI → live options ranked by shared design, licence, hosting and MCP support
Similar systems
Other framework-embedded memory in the catalog, ranked by inbound references.
- Spring AI ChatMemory T3
Wraps conversation memory behind an Advisor abstraction. MessageWindowChatMemory default 20-msg sliding window (preserves system messages); pluggable ChatMemoryRepository backends (in-memory, JDBC, Cassandra, Neo4j). Memory injected as cross-cutting concern at the ChatClient level.
- Flowise Memory T1
Discontinued: Flowise (acquired by Workday, Aug 2025) was sunset in 2026 — code freeze 2026-07-29, GitHub repo archived 2026-08-13, end of life 2026-08-31. Was a visual LangChain canvas with LangChain-native memory nodes (Buffer, Buffer Window, Conversation Summary Buffer) backed by an internal chat_message DB table; Buffer Window kept the last K interactions, Summary Buffer compressed older turns while keeping recent ones verbatim.
- LangGraph Persistence T2
Distinct from LangMem. Built-in checkpointer saves graph state per super-step (short-term, thread-scoped). Store System adds long-term hierarchical key-value memory across threads with optional vector search + TTL. Postgres / Mongo / Redis stores for production.
- AutoGen Memory T2
AutoGen's memory layer: ListMemory chronological context plus teachable agents that vectorise corrections; integrates with Mem0/Zep rather than building deep memory natively. Microsoft AutoGen is in maintenance mode (community managed, bug and security fixes only), and Microsoft points new projects to Microsoft Agent Framework.
- CrewAI Memory T2
Memory subsystem inside the CrewAI orchestration framework; integrates with Mem0 for the long-term tier.
- Hermes Agent memory (Nous Research) T3
Nous Research's open-source self-improving agent keeps an agent-curated MEMORY.md/USER.md notebook injected at session start, full-text (FTS5) search over past sessions that returns raw messages without LLM summarisation, and optional Honcho user modelling. one of the most-starred agent projects of 2026.
Sources (44 cited facts, 4 third-party)
Each fact links to the page it came from; the badge says who published it (how to read sources).
- What it is In-call + integration-based long-term vendor
- What it does & what's distinct Voice agents. Short-term context within call native; long-term memory via webhook integr… vendor
- Claims / benefits Usage-based per minute. Free tier for testing. vendor
- Modalities voice + text vendor
- Created 2024-04 vendor
- Mindshare 1 press ~20 (small YC s jobs third-party
- Funding $5M total Seed · 2024-04 vendor
- Customers / scale 11-50 ppl No named customers publicly disclosed vendor
- Pricing Pay-as-you-go voice $0.07–0.31/min, chat from $0.002/msg, $10 free credits, 20 free conc… vendor
- Compliance SOC 2 Type II; HIPAA; GDPR-compliant vendor
- Data handling SOC 2 Type II; HIPAA; GDPR; PCI DSS compliance; 31+ language support with consistent sec… vendor
- Deployment Managed-only (Retell-hosted; Enterprise dedicated-server add-on; no self-host option lis… vendor
- HQ US third-party
- Founders / pedigree Retell AI (Weijia Yu, founder; ex-Meta engineer; YC W24) third-party
- Memory volume / scale no scale claim — long-term via external CRM integration vendor
- Namespace primitives per-tenant vendor
- MCP support yes — MCP Node lets agents call tools on external MCP servers mid-call vendor
- Webhooks / events webhooks supported vendor
- Import / export JSON via REST (call transcripts, recordings as MP3/WAV URLs) vendor
- Integration count 0 vendor
- Orchestration multi-agent supervisor vendor
- Programmatic control declarative config + REST vendor
- Pricing specifics per-API-call: pay-per-use per minute; free tier vendor
- Agent abstraction multi-agent supervisor vendor
- Memory primitives multiple (in-call short-term + webhook-CRM long-term) vendor
- LLM lock multi-vendor vendor
- Runtimes declarative cross-language vendor
- Session handling sticky session (call-scoped) + persistent via webhook vendor
- Validated verticals voice agents, contact center vendor
- Time to running <10min (hosted SaaS) vendor
- Anti-fit not for non-voice use cases vendor
- Optimised for low-latency voice + integration-based long-term vendor
- Adjacent infrastructure BYO LLM + integrations (or Retell-managed) vendor
- Pros Real-time voice agent platform with memory across calls — strong call-center workflow in… vendor
- Cons Voice-only; smaller mind-share than Vapi. vendor
- Project & sources retellai.com vendor
- adoption-accelerator yc-w24 third-party
- architecture-deployment-locus cloud vendor
- licensing-bucket commercial vendor
- positioning-platform-vs-product platform vendor
- taxonomy-three-layer-rollup agent-infra repo
- compliance-certifications ccpa,gdpr,hipaa,iso27001,soc2-type1,soc2-type2 vendor
- sdk-languages python,rest,typescript vendor
- protocol-support mcp-client,mcp-server vendor
What changed
Changes to this record's lifecycle, licence, release, pricing and hosting facts, from the catalog's git history. Subscribe (Atom)
- 2026-10-22
- Pricing “Pay-per-use” → “Pay-as-you-go voice $0.07–0.31/min, chat from $0.002/msg, $10 free credits, 20 free concurrent calls (+$8/concurrent call/mo); Enterprise custom” source
- Deployment “Both” → “Managed-only (Retell-hosted; Enterprise dedicated-server add-on; no self-host option listed)” source
- MCP support first recorded as “yes — MCP Node lets agents call tools on external MCP servers mid-call” source