diff --git a/bindgen-test.sh b/bindgen-test.sh
index 32257d3..6d73731 100755
--- a/bindgen-test.sh
+++ b/bindgen-test.sh
@@ -33,6 +33,6 @@ case $1 in
     echo "building '$PLUGIN_NAME'..."
     xtp plugin build --path $PLUGIN_NAME
     echo "testing '$PLUGIN_NAME'..."
-    xtp plugin test $PLUGIN_NAME/plugin.wasm --with test.wasm --mock-host mock.wasm
+    EXTISM_ENABLE_WASI_OUTPUT=1 xtp plugin test $PLUGIN_NAME/plugin.wasm --with test.wasm --mock-host mock.wasm
   ;;
 esac
diff --git a/src/index.ts b/src/index.ts
index 19c6376..98c7d0b 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -6,7 +6,8 @@ import {
   EnumType, 
   ArrayType, 
   XtpNormalizedType, 
-  XtpTyped 
+  XtpTyped,
+  Parameter
 } from "@dylibso/xtp-bindgen"
 
 function pythonTypeName(s: string): string {
@@ -78,6 +79,14 @@ function toPythonParamType(property: XtpTyped, required?: boolean): string {
   return t;
 }
 
+function toPythonHostParamType(param: Parameter): string {
+  if (param.contentType === 'application/x-binary') {
+    return 'bytes'
+  } else {
+    return 'str'
+  }
+}
+
 export function render() {
   const tmpl = Host.inputString();
   const ctx = {
@@ -86,7 +95,8 @@ export function render() {
     toPythonType,
     toPythonParamType,
     pythonTypeName,
-    pythonFunctionName
+    pythonFunctionName,
+    toPythonHostParamType
   };
 
   const output = ejs.render(tmpl, ctx);
diff --git a/template/plugin/__init__.py.ejs b/template/plugin/__init__.py.ejs
index ae0dcf9..a3daf91 100644
--- a/template/plugin/__init__.py.ejs
+++ b/template/plugin/__init__.py.ejs
@@ -2,6 +2,7 @@
 
 from typing import Optional, List # noqa: F401
 from datetime import datetime # noqa: F401
+import json
 import extism # pyright: ignore
 import plugin
 
@@ -21,7 +22,7 @@ from pdk_types import <%- Object.values(schema.schemas).map(schema => pythonType
 # And it returns an output <%- toPythonParamType(imp.output) %> (<%- formatCommentLine(imp.output.description) %>)
 <% } -%>
 @extism.import_fn("extism:host/user", "<%- imp.name %>")
-def <%- pythonFunctionName(imp.name) %>(<% if (imp.input) { -%>input: <%- toPythonParamType(imp.input) %><%} -%>) <% if (imp.output) { %> -> <%- toPythonParamType(imp.output) %><% } %>: # pyright: ignore [reportReturnType]
+def _<%- pythonFunctionName(imp.name) %>(<% if (imp.input) { -%>input: <%- toPythonHostParamType(imp.input) %> <%} -%>) <% if (imp.output) { %> -> <%- toPythonHostParamType(imp.output) %> <% } %>: # pyright: ignore [reportReturnType]
   pass
 <% }) %>
 
@@ -34,7 +35,28 @@ def <%- pythonFunctionName(imp.name) %>(<% if (imp.input) { -%>input: <%- toPyth
 <% } -%>
 @extism.plugin_fn
 def <%- ex.name %>():
-  res = plugin.<%- pythonFunctionName(ex.name) %>(<% if (ex.input) { %> extism.input(<%- toPythonParamType(ex.input) %>) <% } %>)
-  extism.output(res)
-
-<% }) %>
+<% if (ex.input) { -%>
+  input = <% if (ex.input.contentType === 'application/x-binary') { %> extism.input_bytes() <% } else { %> extism.input_str() <% } %>
+<% if (ex.input.contentType === 'application/json') { -%>
+<% if (ex.input.xtpType.kind === 'object') { -%>
+  input = <%- toPythonParamType(ex.input) %>.from_json(input)
+<% } else { -%>
+  input = json.loads(input)
+<% } -%>
+<% } -%>
+<% } -%>
+  res = plugin.<%- pythonFunctionName(ex.name) %>(<% if (ex.input) { %> input <% } %>)
+<% if (ex.output) { -%>
+<% if (ex.output.contentType === 'application/x-binary') { %>  extism.output_bytes( <% } else { %>  extism.output_str( <% } %>
+<% if (ex.output.contentType === 'application/json') { -%>
+<% if (ex.output.xtpType.kind === 'object') { -%>
+  res.to_json()
+<% } else { -%>
+  json.dumps(res)
+<% } %>
+<% } else { -%>
+  res
+<% } -%>
+  )
+<% } -%>
+<% }) -%>
diff --git a/template/plugin/pdk_imports.py.ejs b/template/plugin/pdk_imports.py.ejs
index 59ac0f2..8b35130 100644
--- a/template/plugin/pdk_imports.py.ejs
+++ b/template/plugin/pdk_imports.py.ejs
@@ -3,6 +3,7 @@
 from typing import Optional, List # noqa: F401
 from datetime import datetime # noqa: F401
 import extism # noqa: F401 # pyright: ignore
+import json
 
 <% if (Object.values(schema.schemas).length > 0) { %>
 from pdk_types import <%- Object.values(schema.schemas).map(schema => pythonTypeName(schema.name)).join(", ") %> # noqa: F401
@@ -18,8 +19,39 @@ from pdk_types import <%- Object.values(schema.schemas).map(schema => pythonType
 # And it returns an output <%- toPythonParamType(imp.output) %> (<%- formatCommentLine(imp.output.description) %>)
 <% } -%>
 @extism.import_fn("extism:host/user", "<%- imp.name %>")
-def <%- pythonFunctionName(imp.name) %>(<% if (imp.input) { -%>input: <%- toPythonParamType(imp.input) %><%} -%>) <% if (imp.output) { %> -> <%- toPythonParamType(imp.output) %><% } %>: # pyright: ignore [reportReturnType]
+def _<%- pythonFunctionName(imp.name) %>(<% if (imp.input) { -%>input: <%- toPythonHostParamType(imp.input) %> <%} -%>) <% if (imp.output) { %> -> <%- toPythonHostParamType(imp.output) %> <% } %>: # pyright: ignore [reportReturnType]
   pass
+
+def <%- pythonFunctionName(imp.name) %>(<% if (imp.input) { -%>input: <%- toPythonParamType(imp.input) %><%} -%>) <% if (imp.output) { %> -> <%- toPythonParamType(imp.output) %><% } %>: # pyright: ignore [reportReturnType]
+<% if (imp.output) { %>
+  return (
+<% if (imp.output.contentType === 'application/json') { %>
+<% if (imp.output.xtpType.kind === 'object') { %>
+  <%- toPythonParamType(imp.output) %>.from_json(
+<% } else { %>
+  json.loads(
+<% } -%>
+<% } -%>
+<% } -%>
+    _<%- pythonFunctionName(imp.name) %>(
+<% if (imp.input) { -%>
+<% if (imp.input.contentType === 'application/json') { %>
+<% if (imp.input.xtpType.kind === 'object') { %>
+      input.to_json()
+<% } else { %>
+      json.dumps(input)
+<% } -%>
+<% } else { %>
+      input
+<% } -%>
+<% } -%>
+    )
+<% if (imp.output) { %>
+  )
+<% if (imp.output.contentType === 'application/json') { %>
+  )
+<% } -%>
+<% } -%>
 <% }) %>
 
 
diff --git a/template/plugin/pdk_types.py.ejs b/template/plugin/pdk_types.py.ejs
index e6f24e7..edea53e 100644
--- a/template/plugin/pdk_types.py.ejs
+++ b/template/plugin/pdk_types.py.ejs
@@ -5,8 +5,9 @@ from enum import Enum # noqa: F401
 from typing import Optional, List # noqa: F401
 from datetime import datetime # noqa: F401
 from dataclasses import dataclass # noqa: F401
-
-import extism # noqa: F401 # pyright: ignore
+from dataclass_wizard import JSONWizard # noqa: F401
+from dataclass_wizard.type_def import JSONObject
+from base64 import b64encode, b64decode
 
 <% Object.values(schema.schemas).forEach(schema => { %>
     <% if (schema.enum) { %>
@@ -16,7 +17,7 @@ class <%- pythonTypeName(schema.name) %>(Enum):
 <% }) %>
     <% } else { %>
 @dataclass
-class <%- pythonTypeName(schema.name) %>(extism.Json):
+class <%- pythonTypeName(schema.name) %>(JSONWizard):
 <% schema.properties.forEach(p => { -%>
 <% if (!p.nullable && p.required) {%>
   <% if (p.description) { -%>
@@ -35,6 +36,23 @@ class <%- pythonTypeName(schema.name) %>(extism.Json):
 <% } %>
 <% }) %>
 
+    @classmethod
+    def _pre_from_dict(cls, o: JSONObject) -> JSONObject:
+<% schema.properties.forEach(p => { -%>
+<% if (p.xtpType.kind === 'buffer') {%>
+        o['<%- p.name %>'] = b64decode(o['<%- p.name %>'])
+<% } -%>
+<% }) -%>
+        return o
+
+    def _pre_dict(self):
+<% schema.properties.forEach(p => { -%>
+<% if (p.xtpType.kind === 'buffer') {%>
+        self.<%- p.name %> = b64encode(self.<%- p.name %>).decode("utf-8")
+<% } -%>
+<% }) -%>
+        return
+
 <% } %>
 <% }); %>
 
diff --git a/template/prepare.sh b/template/prepare.sh
index 546e38f..8411ac7 100644
--- a/template/prepare.sh
+++ b/template/prepare.sh
@@ -40,5 +40,3 @@ if ! command_exists extism-py; then
   sleep 2
   exit 1
 fi
-
-
diff --git a/template/pyproject.toml.ejs b/template/pyproject.toml.ejs
index 158682a..68d8d17 100644
--- a/template/pyproject.toml.ejs
+++ b/template/pyproject.toml.ejs
@@ -3,8 +3,10 @@ name = "<%= project.name %>"
 version = "0.1.0"
 description = "Add your description here"
 readme = "README.md"
-requires-python = ">=3.12"
-dependencies = []
+requires-python = ">=3.13,<3.14"
+dependencies = [
+    "dataclass-wizard>=0.33.0,<0.34.0"
+]
 
 [tool.uv]
 dev-dependencies = [
diff --git a/template/xtp.toml.ejs b/template/xtp.toml.ejs
index 2ff3cad..5b6ed23 100644
--- a/template/xtp.toml.ejs
+++ b/template/xtp.toml.ejs
@@ -8,7 +8,7 @@ name = "<%= project.name %>"
 
 [scripts]
 # xtp plugin build runs this script to generate the wasm file
-build = "PYTHONPATH=./plugin extism-py -o plugin.wasm plugin/__init__.py"
+build = "PYTHONPATH=./plugin:./.venv/lib/python3.13/site-packages extism-py -o plugin.wasm plugin/__init__.py"
 
 # xtp plugin init runs this script to format the code
 format = "uv run ruff format plugin/*.py"