retell-sdk
The official Python library for the retell API
Decision gist · record as of 2026-08-14
Yes. The package is actively maintained, has no known vulnerabilities, installs with low friction, uses a permissive license, and provides a well-typed, production-ready client for the Retell API. Install it if you are building voice agent applications with Retell.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires RETELL_API_KEY environment variable or explicit api_key parameter to authenticate with the Retell service.
- Low friction installation with a pure-Python wheel and no compiled dependencies.
- Active maintenance with a release 4 days ago and recent commits.
License · maintenance · safety
Apache-2.0 (permissive) — Apache-2.0 is permissive; you can use, modify, and distribute this library freely in commercial and private projects with minimal restrictions.
last release 2026-08-10 (4 days) · last repo commit 2026-08-11 · 59 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 577,082 downloads/mo, #5,926 on PyPI
Alternatives
Verify before relying
pip install retell-sdk
import os
from retell import Retell
client = Retell(api_key=os.environ.get("RETELL_API_KEY"))
agent_response = client.agent.create(
response_engine={"llm_id": "llm_234sdertfsdsfsdf", "type": "retell-llm"},
voice_id="retell-Cimo",
)
print(agent_response.agent_id)- Whether the MCP Server feature is production-ready or experimental.
- Performance characteristics and rate-limit behavior under high concurrency.
- Whether aiohttp backend provides measurable concurrency improvements over httpx in typical workloads.
What it is and what it does
Retell-sdk is the official Python client for the Retell REST API, a service for building and managing voice agents. It wraps the Retell API endpoints with typed request and response models, automatic retries, and configurable timeouts. The library supports both synchronous (Retell) and asynchronous (AsyncRetell) clients, both powered by httpx by default, with an optional aiohttp backend for async workloads.
The package is designed for developers building voice-based conversational AI applications. It handles authentication, error mapping (distinguishing connection errors, rate limits, and HTTP status codes), and provides Pydantic models for responses with helper methods like to_json() and to_dict(). Type hints throughout enable IDE autocomplete and type checking, and the library includes automatic retry logic for transient failures.
Use it for
- Create and configure voice agents with custom LLM backends and voice settings via the agent.create() endpoint.
- Build async applications that manage multiple concurrent voice agent interactions without blocking.
- Integrate Retell voice capabilities into existing Python applications with full type safety and IDE support.
- Handle API errors gracefully by catching specific exception types (RateLimitError, AuthenticationError, etc.).
- Use the optional aiohttp backend to optimize concurrency performance in high-throughput async scenarios.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
The package is actively maintained, has no known vulnerabilities, installs with low friction, uses a permissive license, and provides a well-typed, production-ready client for the Retell API. Install it if you are building voice agent applications with Retell.
Install
retell-sdk on PyPI
Before you install
Low friction installation with a pure-Python wheel and no compiled dependencies. Active maintenance with a release 4 days ago and recent commits. Supports Python 3.9 through 3.14.
Requires RETELL_API_KEY environment variable or explicit api_key parameter to authenticate with the Retell service.
License in practice
Apache-2.0 is permissive; you can use, modify, and distribute this library freely in commercial and private projects with minimal restrictions.
Quickstart
pip install retell-sdk
import os
from retell import Retell
client = Retell(api_key=os.environ.get("RETELL_API_KEY"))
agent_response = client.agent.create(
response_engine={"llm_id": "llm_234sdertfsdsfsdf", "type": "retell-llm"},
voice_id="retell-Cimo",
)
print(agent_response.agent_id)Verify before relying
- Whether the MCP Server feature is production-ready or experimental.
- Performance characteristics and rate-limit behavior under high concurrency.
- Whether aiohttp backend provides measurable concurrency improvements over httpx in typical workloads.
Package facts
| License | Apache-2.0 permissive |
| Python support | Supports the current Python release >=3.9 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 8 packagesanyiocached-propertycryptographydistrohttpxpydanticsniffiotyping-extensions |
| Maintenance | Actively maintained 4 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 577,082 / month, #5,926 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Intended Audience :: DevelopersLicense :: OSI Approved :: Apache Software LicenseOperating System :: MacOSOperating System :: Microsoft :: WindowsOperating System :: OS IndependentOperating System :: POSIXOperating System :: POSIX :: LinuxProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: 3.9Topic :: Software Development :: Libraries :: Python ModulesTyping :: Typed |
Evidence: retell_sdk-5.61.0-py3-none-any.whl
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