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Asynchronous pure Python gRPC client and server implementation supporting asyncio, uvloop, curio and trio

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Asynchronous pure Python gRPC client and server implementation supporting asyncio, uvloop, curio and trio (achieved with anyio compatibility layer).


  • CPython >= 3.5
  • PyPy >= 3.5


Latest PyPI version:

pip install purerpc

Latest development version:

pip install git+

By default purerpc uses asyncio event loop, if you want to use uvloop, curio or trio, please install them manually.

protoc plugin

purerpc adds protoc-gen-purerpc plugin for protoc to your PATH enviroment variable so you can use it to generate service definition and stubs:

protoc --purerpc_out=. --python_out=. -I. greeter.proto

or, if you installed grpcio_tools Python package:

python -m grpc_tools.protoc --purerpc_out=. --python_out=. -I. greeter.proto


NOTE: greeter_grpc module is generated by purerpc's protoc-gen-purerpc plugin.

Below are the examples for Python 3.6 and above which introduced asynchronous generators as a language concept. For Python 3.5, where native asynchronous generators are not supported, you can use async_generator library for this purpose. Just mark yielding coroutines with @async_generator decorator and use await yield_(value) and await yield_from_(async_iterable) instead of yield.


from greeter_pb2 import HelloRequest, HelloReply
from greeter_grpc import GreeterServicer
from purerpc import Server

class Greeter(GreeterServicer):
    async def SayHello(self, message):
        return HelloReply(message="Hello, " +

    async def SayHelloToMany(self, input_messages):
        async for message in input_messages:
            yield HelloReply(message=f"Hello, {}")

server = Server(50055)
server.serve(backend="asyncio")  # backend can also be one of: "uvloop", "curio", "trio"


import anyio
import purerpc
from greeter_pb2 import HelloRequest, HelloReply
from greeter_grpc import GreeterStub

async def gen():
    for i in range(5):
        yield HelloRequest(name=str(i))

async def main():
    async with purerpc.insecure_channel("localhost", 50055) as channel:
        stub = GreeterStub(channel)
        reply = await stub.SayHello(HelloRequest(name="World"))

        async for reply in stub.SayHelloToMany(gen()):

if __name__ == "__main__":, backend="asyncio")  # backend can also be one of: "uvloop", "curio", "trio"

You can mix server and client code, for example make a server that requests something using purerpc from another gRPC server, etc.

More examples in misc/ folder

Release 0.6.1 (2020-04-13)

Bug Fixes

  • build in PyPy 3.6, remove 3.5 builds from CI (d1bcc9d)
  • remove CPython 3.5 builds (7488ba8)

Release 0.6.0 (2020-04-13)


  • Add TLS Support

Release 0.5.2 (2019-07-23)


  • additional exception shielding for asyncio (3cbd35c)

Release 0.5.1 (2019-07-23)

Bug Fixes

  • async generators on python 3.5 (1c19229)

Release 0.5.0 (2019-07-23)


  • can now pass contextmngr or setup_fn/teardown_fn to add_service (208dd95)

Release 0.4.1 (2019-07-22)


  • remove undocumented use of raw_socket in anyio (6de2c9a)

Release 0.4.0 (2019-07-22)

Bug Fixes


  • add state property to GRPCStream (0019d8c)
  • answer PING frames (c829901)
  • change MAX_CONCURRENT_STREAMS from 1000 to 65536 (d2d461f)
  • decouple h2 and grpclib logic (1f4e6b0)
  • support percent-encoded grpc-message header (c6636f4)
  • change default max message length to 32 MB

Release 0.3.2 (2019-02-15)

Bug Fixes

  • fix dependencies, remove some of anyio monkey patches (ac6c5c2)

Release 0.3.1 (2019-02-15)

Bug Fixes

  • fix pickling error in purerpc.test_utils._WrappedResult (9f0a63d)

Release 0.3.0 (2019-02-14)


  • expose new functions in purerpc.test_utils (07b10e1)
  • migrate to pytest (95c0a8b)


  • purerpc.test_utils.PureRPCTestCase is removed

Release 0.2.0 (2019-02-10)


  • add backend option to Server.serve (5f47f8e)
  • add support for Python 3.5 (a681192)
  • improved exception handling in test utils (b1df796)
  • migrate to anyio (746b1c2)


  • Server and test now use asyncio event loop by default, this behaviour can be changed with PURERPC_BACKEND environment variable
  • purerpc.Channel is removed, migrate to purerpc.insecure_channel async context manager (now supports correct shutdown)

Release 0.1.6

  • Allow passing request headers to method handlers in request argument
  • Allow passing custom metadata to method stub calls (in metadata optional keyword argument)

Release 0.1.5

  • Enforce SO_KEEPALIVE with small timeouts
  • Expose PureRPCTestCase in purerpc API for unit testing purerpc services

Release 0.1.4

  • Speed up protoc plugin

Release 0.1.3 [PyPI only]

  • Fix long description on PyPI

Release 0.1.2

  • Fix unit tests on Python 3.7

Release 0.1.0

  • Implement immediate mode

Release 0.0.1

  • Initial release

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