diff --git a/README.md b/README.md
index 711148d..d90e651 100644
--- a/README.md
+++ b/README.md
@@ -90,6 +90,7 @@ Additionally, we provide scripts to read logs from your function and to wipe all
 
 This tinyFaaS prototype only supports functions written for NodeJS 20, Python 3.9, and binary functions.
 A good place to get started with writing functions is the selection of test functions in [`./test/fns`](./test/fns/).
+HTTP headers and GRPC Metadata are accessible in NodeJS and Python functions as key values. Check the "show-headers" test functions for more information.
 
 #### NodeJS 20
 
diff --git a/pkg/coap/coap.go b/pkg/coap/coap.go
index 4a82cd0..6d29d32 100644
--- a/pkg/coap/coap.go
+++ b/pkg/coap/coap.go
@@ -8,6 +8,8 @@ import (
 	"github.com/pfandzelter/go-coap"
 )
 
+const async = false
+
 func Start(r *rproxy.RProxy, listenAddr string) {
 
 	h := coap.FuncHandler(
@@ -17,8 +19,6 @@ func Start(r *rproxy.RProxy, listenAddr string) {
 			log.Printf("is confirmable: %v", m.IsConfirmable())
 			log.Printf("path: %s", m.PathString())
 
-			async := false
-
 			p := m.PathString()
 
 			for p != "" && p[0] == '/' {
@@ -27,7 +27,7 @@ func Start(r *rproxy.RProxy, listenAddr string) {
 
 			log.Printf("have request for path: %s (async: %v)", p, async)
 
-			s, res := r.Call(p, m.Payload, async)
+			s, res := r.Call(p, m.Payload, async, nil)
 
 			mes := &coap.Message{
 				Type:      coap.Acknowledgement,
diff --git a/pkg/docker/runtimes/python3/functionhandler.py b/pkg/docker/runtimes/python3/functionhandler.py
index 748e596..08af6a8 100644
--- a/pkg/docker/runtimes/python3/functionhandler.py
+++ b/pkg/docker/runtimes/python3/functionhandler.py
@@ -32,8 +32,11 @@ def do_POST(self) -> None:
             if d == "":
                 d = None
 
+            # Read headers into a dictionary
+            headers: typing.Dict[str, str] = {k: v for k, v in self.headers.items()}
+
             try:
-                res = fn.fn(d)
+                res = fn.fn(d, headers)
                 self.send_response(200)
                 self.end_headers()
                 if res is not None:
diff --git a/pkg/grpc/grpc.go b/pkg/grpc/grpc.go
index 91d32db..73ed25f 100644
--- a/pkg/grpc/grpc.go
+++ b/pkg/grpc/grpc.go
@@ -9,6 +9,7 @@ import (
 	"github.com/OpenFogStack/tinyFaaS/pkg/grpc/tinyfaas"
 	"github.com/OpenFogStack/tinyFaaS/pkg/rproxy"
 	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
 )
 
 // GRPCServer is the grpc endpoint for this tinyFaaS instance.
@@ -21,7 +22,21 @@ func (gs *GRPCServer) Request(ctx context.Context, d *tinyfaas.Data) (*tinyfaas.
 
 	log.Printf("have request for path: %s (async: %v)", d.FunctionIdentifier, false)
 
-	s, res := gs.r.Call(d.FunctionIdentifier, []byte(d.Data), false)
+	// Extract metadata from the gRPC context
+	md, ok := metadata.FromIncomingContext(ctx)
+	headers := make(map[string]string)
+	if ok {
+		// Convert metadata to map[string]string
+		for k, v := range md {
+			if len(v) > 0 {
+				headers[k] = v[0]
+			}
+		}
+	} else {
+		log.Print("failed to extract metadata from context, using empty headers GRPC request")
+	}
+
+	s, res := gs.r.Call(d.FunctionIdentifier, []byte(d.Data), false, headers)
 
 	switch s {
 	case rproxy.StatusOK:
diff --git a/pkg/http/http.go b/pkg/http/http.go
index 4bd9bae..81af12d 100644
--- a/pkg/http/http.go
+++ b/pkg/http/http.go
@@ -31,7 +31,12 @@ func Start(r *rproxy.RProxy, listenAddr string) {
 			return
 		}
 
-		s, res := r.Call(p, req_body, async)
+		headers := make(map[string]string)
+		for k, v := range req.Header {
+			headers[k] = v[0]
+		}
+
+		s, res := r.Call(p, req_body, async, headers)
 
 		switch s {
 		case rproxy.StatusOK:
diff --git a/pkg/rproxy/rproxy.go b/pkg/rproxy/rproxy.go
index 4ddec27..af4137f 100644
--- a/pkg/rproxy/rproxy.go
+++ b/pkg/rproxy/rproxy.go
@@ -7,6 +7,7 @@ import (
 	"log"
 	"math/rand"
 	"net/http"
+	"regexp"
 	"sync"
 )
 
@@ -59,7 +60,7 @@ func (r *RProxy) Del(name string) error {
 	return nil
 }
 
-func (r *RProxy) Call(name string, payload []byte, async bool) (Status, []byte) {
+func (r *RProxy) Call(name string, payload []byte, async bool, headers map[string]string) (Status, []byte) {
 
 	handler, ok := r.hosts[name]
 
@@ -75,18 +76,25 @@ func (r *RProxy) Call(name string, payload []byte, async bool) (Status, []byte)
 
 	log.Printf("chosen handler: %s", h)
 
-	// call function
+	req, err := http.NewRequest("POST", fmt.Sprintf("http://%s:8000/fn", h), bytes.NewBuffer(payload))
+	if err != nil {
+		log.Print(err)
+		return StatusError, nil
+	}
+	for k, v := range headers {
+		cleanedKey := cleanHeaderKey(k) // remove special chars from key
+		req.Header.Set(cleanedKey, v)
+	}
+
+	// call function asynchronously
 	if async {
 		log.Printf("async request accepted")
 		go func() {
-			resp, err := http.Post(fmt.Sprintf("http://%s:8000/fn", h), "application/binary", bytes.NewBuffer(payload))
-
-			if err != nil {
+			resp, err2 := http.DefaultClient.Do(req)
+			if err2 != nil {
 				return
 			}
-
 			resp.Body.Close()
-
 			log.Printf("async request finished")
 		}()
 		return StatusAccepted, nil
@@ -94,8 +102,7 @@ func (r *RProxy) Call(name string, payload []byte, async bool) (Status, []byte)
 
 	// call function and return results
 	log.Printf("sync request starting")
-	resp, err := http.Post(fmt.Sprintf("http://%s:8000/fn", h), "application/binary", bytes.NewBuffer(payload))
-
+	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		log.Print(err)
 		return StatusError, nil
@@ -115,3 +122,9 @@ func (r *RProxy) Call(name string, payload []byte, async bool) (Status, []byte)
 
 	return StatusOK, res_body
 }
+func cleanHeaderKey(key string) string {
+	// a regex pattern to match special characters
+	re := regexp.MustCompile(`[:()<>@,;:\"/[\]?={} \t]`)
+	// Replace special characters with an empty string
+	return re.ReplaceAllString(key, "")
+}
diff --git a/test/fns/echo-js/index.js b/test/fns/echo-js/index.js
index 414500e..493ff92 100644
--- a/test/fns/echo-js/index.js
+++ b/test/fns/echo-js/index.js
@@ -1,6 +1,7 @@
 
 module.exports = (req, res) => {
   const response = req.body;
+  const headers = req.headers; // headers from the http request or GRPC metadata
 
   console.log(response);
 
diff --git a/test/fns/echo/fn.py b/test/fns/echo/fn.py
index d934c9f..7b8231a 100644
--- a/test/fns/echo/fn.py
+++ b/test/fns/echo/fn.py
@@ -2,6 +2,6 @@
 
 import typing
 
-def fn(input: typing.Optional[str]) -> typing.Optional[str]:
+def fn(input: typing.Optional[str], headers: typing.Optional[typing.Dict[str, str]]) -> typing.Optional[str]:
     """echo the input"""
     return input
diff --git a/test/fns/show-headers-js/index.js b/test/fns/show-headers-js/index.js
new file mode 100644
index 0000000..e50a16f
--- /dev/null
+++ b/test/fns/show-headers-js/index.js
@@ -0,0 +1,9 @@
+
+module.exports = (req, res) => {
+  const body = req.body;
+  const headers = req.headers; // headers from the http request or GRPC metadata
+
+  console.log("Headers:", headers);
+
+  res.send(headers);
+}
diff --git a/test/fns/show-headers-js/package.json b/test/fns/show-headers-js/package.json
new file mode 100644
index 0000000..f04076a
--- /dev/null
+++ b/test/fns/show-headers-js/package.json
@@ -0,0 +1 @@
+{"name": "fn", "version": "1.0.0", "main": "index.js"}
\ No newline at end of file
diff --git a/test/fns/show-headers/fn.py b/test/fns/show-headers/fn.py
new file mode 100644
index 0000000..775f3d2
--- /dev/null
+++ b/test/fns/show-headers/fn.py
@@ -0,0 +1,9 @@
+import json
+import typing
+
+def fn(input: typing.Optional[str], headers: typing.Optional[typing.Dict[str, str]]) -> typing.Optional[str]:
+    """echo the input"""
+    if headers is not None:
+        return json.dumps(headers)
+    else:
+        return "{}"
\ No newline at end of file
diff --git a/test/fns/show-headers/requirements.txt b/test/fns/show-headers/requirements.txt
new file mode 100644
index 0000000..e69de29
diff --git a/test/fns/sieve-of-eratosthenes/index.js b/test/fns/sieve-of-eratosthenes/index.js
index 9a6b99f..7b95446 100644
--- a/test/fns/sieve-of-eratosthenes/index.js
+++ b/test/fns/sieve-of-eratosthenes/index.js
@@ -12,7 +12,7 @@ module.exports = (req, res) => {
     }
   }
 
-  response = ("Found " + primes.length + " primes under " + max);
+  let response = ("Found " + primes.length + " primes under " + max);
 
   console.log(response);
 
diff --git a/test/test_all.py b/test/test_all.py
index e050a62..11a5fa4 100755
--- a/test/test_all.py
+++ b/test/test_all.py
@@ -2,6 +2,7 @@
 
 import unittest
 
+import json
 import os
 import os.path as path
 import signal
@@ -48,7 +49,7 @@ def setUpModule() -> None:
         uname = os.uname()
         if uname.machine == "x86_64":
             arch = "amd64"
-        elif uname.machine == "arm64":
+        elif uname.machine == "arm64" or uname.machine == "aarch64":
             arch = "arm64"
         else:
             raise Exception(f"Unsupported architecture: {uname.machine}")
@@ -534,6 +535,136 @@ def test_invoke_grpc(self) -> None:
         self.assertIsNotNone(response)
         self.assertEqual(response.response, payload)
 
+class TestShowHeadersJS(TinyFaaSTest):
+    fn = ""
+
+    @classmethod
+    def setUpClass(cls) -> None:
+        super(TestShowHeadersJS, cls).setUpClass()
+        cls.fn = startFunction(path.join(fn_path, "show-headers-js"), "headersjs", "nodejs", 1)
+
+    def setUp(self) -> None:
+        super(TestShowHeadersJS, self).setUp()
+        self.fn = TestShowHeadersJS.fn
+
+    def test_invoke_http(self) -> None:
+        """invoke a function"""
+
+        # make a request to the function with a custom headers
+        req = urllib.request.Request(
+            f"http://{self.host}:{self.http_port}/{self.fn}",
+            headers={"lab": "scalable_software_systems_group"},
+        )
+
+        res = urllib.request.urlopen(req, timeout=10)
+
+        # check the response
+        self.assertEqual(res.status, 200)
+        response_body = res.read().decode("utf-8")
+        response_json = json.loads(response_body)
+        self.assertIn("lab", response_json)
+        self.assertEqual(response_json["lab"], "scalable_software_systems_group") # custom header
+        self.assertIn("user-agent", response_json)
+        self.assertEqual(response_json["user-agent"], "Python-urllib/3.11") # python client
+
+        return
+
+#     def test_invoke_coap(self) -> None: # CoAP does not support headers
+
+
+    def test_invoke_grpc(self) -> None:
+        """invoke a function"""
+        try:
+            import grpc
+        except ImportError:
+            self.skipTest(
+                "grpc is not installed -- if you want to run gRPC tests, install the dependencies in requirements.txt"
+            )
+
+        import tinyfaas_pb2
+        import tinyfaas_pb2_grpc
+
+        # make a request to the function with a payload
+        payload = ""
+        metadata = (("lab", "scalable_software_systems_group"),)
+
+        with grpc.insecure_channel(f"{self.host}:{self.grpc_port}") as channel:
+            stub = tinyfaas_pb2_grpc.TinyFaaSStub(channel)
+            response = stub.Request(
+                tinyfaas_pb2.Data(functionIdentifier=self.fn, data=payload), metadata=metadata
+            )
+
+        response_json = json.loads(response.response)
+        self.assertIn("lab", response_json)
+        self.assertEqual(response_json["lab"], "scalable_software_systems_group") # custom header
+        self.assertIn("user-agent", response_json)
+        self.assertIn("grpc-python/1.64.1", response_json["user-agent"]) # client header
+
+class TestShowHeaders(TinyFaaSTest): # Note: In Python, the http.server module (and many other HTTP libraries) automatically capitalizes the first character of each word in the header keys.
+    fn = ""
+
+    @classmethod
+    def setUpClass(cls) -> None:
+        super(TestShowHeaders, cls).setUpClass()
+        cls.fn = startFunction(path.join(fn_path, "show-headers"), "headers", "python3", 1)
+
+    def setUp(self) -> None:
+        super(TestShowHeaders, self).setUp()
+        self.fn = TestShowHeaders.fn
+
+    def test_invoke_http(self) -> None:
+        """invoke a function"""
+
+        # make a request to the function with a custom headers
+        req = urllib.request.Request(
+            f"http://{self.host}:{self.http_port}/{self.fn}",
+            headers={"Lab": "scalable_software_systems_group"},
+        )
+
+        res = urllib.request.urlopen(req, timeout=10)
+
+        # check the response
+        self.assertEqual(res.status, 200)
+        response_body = res.read().decode("utf-8")
+        response_json = json.loads(response_body)
+        self.assertIn("Lab", response_json)
+        self.assertEqual(response_json["Lab"], "scalable_software_systems_group") # custom header
+        self.assertIn("User-Agent", response_json)
+        self.assertIn("Python-urllib", response_json["User-Agent"]) # python client
+
+        return
+
+#     def test_invoke_coap(self) -> None: # CoAP does not support headers, instead you have
+
+    def test_invoke_grpc(self) -> None:
+        """invoke a function"""
+        try:
+            import grpc
+        except ImportError:
+            self.skipTest(
+                "grpc is not installed -- if you want to run gRPC tests, install the dependencies in requirements.txt"
+            )
+
+        import tinyfaas_pb2
+        import tinyfaas_pb2_grpc
+
+        # make a request to the function with a payload
+        payload = ""
+        metadata = (("lab", "scalable_software_systems_group"),)
+
+        with grpc.insecure_channel(f"{self.host}:{self.grpc_port}") as channel:
+            stub = tinyfaas_pb2_grpc.TinyFaaSStub(channel)
+            response = stub.Request(
+                tinyfaas_pb2.Data(functionIdentifier=self.fn, data=payload), metadata=metadata
+            )
+
+        response_json = json.loads(response.response)
+
+        self.assertIn("Lab", response_json)
+        self.assertEqual(response_json["Lab"], "scalable_software_systems_group") # custom header
+        self.assertIn("User-Agent", response_json)
+        self.assertIn("grpc-python", response_json["User-Agent"]) # client header
+
 
 if __name__ == "__main__":
     # check that make is installed