diff --git a/.github/actions/spelling/allow.txt b/.github/actions/spelling/allow.txt
index a016962c..da68a546 100644
--- a/.github/actions/spelling/allow.txt
+++ b/.github/actions/spelling/allow.txt
@@ -1,17 +1,10 @@
 AAgent
+ACMRTUXB
 ACard
 AClient
-ACMRTUXB
-aconnect
-adk
 AError
 AFast
-agentic
 AGrpc
-aio
-aiomysql
-amannn
-aproject
 ARequest
 ARun
 AServer
@@ -19,6 +12,26 @@ AServers
 AService
 AStarlette
 AUser
+DSNs
+EUR
+GBP
+GVsb
+INR
+JPY
+JSONRPCt
+JWS
+Llm
+POSTGRES
+RUF
+SLF
+Tful
+aconnect
+adk
+agentic
+aio
+aiomysql
+amannn
+aproject
 autouse
 backticks
 cla
@@ -29,32 +42,23 @@ coro
 datamodel
 deepwiki
 drivername
-DSNs
 dunders
 euo
-EUR
 excinfo
 fernet
 fetchrow
 fetchval
-GBP
 genai
 getkwargs
 gle
-GVsb
 ietf
 initdb
 inmemory
-INR
 isready
-JPY
-JSONRPCt
-JWS
 kwarg
 langgraph
 lifecycles
 linting
-Llm
 lstrips
 mikeas
 mockurl
@@ -64,7 +68,6 @@ oidc
 opensource
 otherurl
 postgres
-POSTGRES
 postgresql
 protoc
 pyi
@@ -74,14 +77,11 @@ pyversions
 redef
 respx
 resub
-RUF
-SLF
 socio
 sse
 tagwords
 taskupdate
 testuuid
-Tful
 tiangolo
 typeerror
 vulnz
diff --git a/README.md b/README.md
index 4964376e..d77b07a5 100644
--- a/README.md
+++ b/README.md
@@ -48,7 +48,9 @@ Install the core SDK and any desired extras using your preferred package manager
 | ------------------------ | ------------------------------------------ | -------------------------------------------- |
 | **Core SDK**             | `uv add a2a-sdk`                           | `pip install a2a-sdk`                        |
 | **All Extras**           | `uv add "a2a-sdk[all]"`                    | `pip install "a2a-sdk[all]"`                 |
-| **HTTP Server**          | `uv add "a2a-sdk[http-server]"`            | `pip install "a2a-sdk[http-server]"`         |
+| **protobuf**             | `uv add "a2a-sdk[proto]"`                  | `pip install "a2a-sdk[proto]"`               |
+| **JSON-RPC Server**      | `uv add "a2a-sdk[jsonrpc-server]"`         | `pip install "a2a-sdk[jsonrpc-server]"`         |
+| **HTTP (REST) Server**   | `uv add "a2a-sdk[http-server]"`            | `pip install "a2a-sdk[http-server]"`         |
 | **gRPC Support**         | `uv add "a2a-sdk[grpc]"`                   | `pip install "a2a-sdk[grpc]"`                |
 | **OpenTelemetry Tracing**| `uv add "a2a-sdk[telemetry]"`              | `pip install "a2a-sdk[telemetry]"`           |
 | **Encryption**           | `uv add "a2a-sdk[encryption]"`             | `pip install "a2a-sdk[encryption]"`          |
diff --git a/pyproject.toml b/pyproject.toml
index 46f7400a..3fb811c0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,8 +11,6 @@ dependencies = [
   "httpx>=0.28.1",
   "httpx-sse>=0.4.0",
   "pydantic>=2.11.3",
-  "protobuf>=5.29.5",
-  "google-api-core>=1.26.0",
 ]
 
 classifiers = [
@@ -29,9 +27,11 @@ classifiers = [
 ]
 
 [project.optional-dependencies]
-http-server = ["fastapi>=0.115.2", "sse-starlette", "starlette"]
+proto = ["protobuf>=5.29.5"]
+jsonrpc-server = ["fastapi>=0.115.2", "sse-starlette", "starlette"]
+http-server = ["a2a-sdk[jsonrpc-server]", "a2a-sdk[proto]"]
 encryption = ["cryptography>=43.0.0"]
-grpc = ["grpcio>=1.60", "grpcio-tools>=1.60", "grpcio_reflection>=1.7.0"]
+grpc = ["grpcio>=1.60", "grpcio-tools>=1.60", "grpcio_reflection>=1.7.0", "google-api-core>=1.26.0", "a2a-sdk[proto]"]
 telemetry = ["opentelemetry-api>=1.33.0", "opentelemetry-sdk>=1.33.0"]
 postgresql = ["sqlalchemy[asyncio,postgresql-asyncpg]>=2.0.0"]
 mysql = ["sqlalchemy[asyncio,aiomysql]>=2.0.0"]
diff --git a/src/a2a/utils/proto_utils.py b/src/a2a/utils/proto_utils.py
index e619cd72..7e87824e 100644
--- a/src/a2a/utils/proto_utils.py
+++ b/src/a2a/utils/proto_utils.py
@@ -7,7 +7,13 @@
 
 from typing import Any
 
-from google.protobuf import json_format, struct_pb2
+
+try:
+    from google.protobuf import json_format, struct_pb2
+except ImportError as e:
+    raise ImportError(
+        'proto-utils requires protobuf. Install with "pip install a2a-sdk[proto]"'
+    ) from e
 
 from a2a import types
 from a2a.grpc import a2a_pb2