diff --git a/Cargo.lock b/Cargo.lock
index faaeaa4c86..206bdcb00e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2066,6 +2066,8 @@ name = "execution_layer"
 version = "0.1.0"
 dependencies = [
  "async-trait",
+ "bytes 1.1.0",
+ "environment",
  "eth1",
  "eth2_serde_utils 0.1.0",
  "futures",
@@ -2076,6 +2078,8 @@ dependencies = [
  "slog",
  "tokio",
  "types",
+ "warp",
+ "warp_utils",
 ]
 
 [[package]]
diff --git a/beacon_node/execution_layer/Cargo.toml b/beacon_node/execution_layer/Cargo.toml
index 7883d02caa..7680c9e831 100644
--- a/beacon_node/execution_layer/Cargo.toml
+++ b/beacon_node/execution_layer/Cargo.toml
@@ -17,3 +17,7 @@ eth2_serde_utils = { path = "../../consensus/serde_utils" }
 serde_json = "1.0.58"
 serde = { version = "1.0.116", features = ["derive"] }
 eth1 = { path = "../eth1" }
+warp = { git = "https://github.com/paulhauner/warp ", branch = "cors-wildcard" }
+warp_utils = { path = "../../common/warp_utils" }
+environment = { path = "../../lighthouse/environment" }
+bytes = "1.1.0"
diff --git a/beacon_node/execution_layer/src/engine_api/http.rs b/beacon_node/execution_layer/src/engine_api/http.rs
index ff292b0435..eb638b6a5f 100644
--- a/beacon_node/execution_layer/src/engine_api/http.rs
+++ b/beacon_node/execution_layer/src/engine_api/http.rs
@@ -53,11 +53,9 @@ impl HttpJsonRpc {
             id: 1,
         };
 
-        let url: &str = self.url.as_ref();
-
         let body: JsonResponseBody = self
             .client
-            .post(url)
+            .post(self.url.full.clone())
             .timeout(timeout)
             .header(CONTENT_TYPE, "application/json")
             .json(&body)
@@ -297,3 +295,67 @@ struct JsonForkChoiceUpdatedRequest {
     head_block_hash: Hash256,
     finalized_block_hash: Hash256,
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::test_utils::MockServer;
+    use std::future::Future;
+    use std::sync::Arc;
+    use types::MainnetEthSpec;
+
+    struct Tester {
+        server: MockServer,
+        echo_client: Arc<HttpJsonRpc>,
+    }
+
+    impl Tester {
+        pub fn new() -> Self {
+            let server = MockServer::unit_testing::<MainnetEthSpec>();
+            let echo_url = SensitiveUrl::parse(&format!("{}/echo", server.url())).unwrap();
+            let echo_client = Arc::new(HttpJsonRpc::new(echo_url).unwrap());
+
+            Self {
+                server,
+                echo_client,
+            }
+        }
+
+        pub async fn assert_request_equals<R, F>(
+            self,
+            request_func: R,
+            expected_json: serde_json::Value,
+        ) -> Self
+        where
+            R: Fn(Arc<HttpJsonRpc>) -> F,
+            F: Future<Output = ()>,
+        {
+            request_func(self.echo_client.clone()).await;
+            let request_bytes = self.server.last_echo_request().await;
+            let request_json: serde_json::Value =
+                serde_json::from_slice(&request_bytes).expect("request was not valid json");
+            if request_json != expected_json {
+                panic!(
+                    "json mismatch!\n\nobserved: {}\n\nexpected: {}\n\n",
+                    request_json.to_string(),
+                    expected_json.to_string()
+                )
+            }
+            self
+        }
+    }
+
+    #[tokio::test]
+    async fn forkchoice_updated_request() {
+        Tester::new()
+            .assert_request_equals(
+                |client| async move {
+                    let _ = client
+                        .forkchoice_updated(Hash256::repeat_byte(0), Hash256::repeat_byte(1))
+                        .await;
+                },
+                json!("meow"),
+            )
+            .await;
+    }
+}
diff --git a/beacon_node/execution_layer/src/lib.rs b/beacon_node/execution_layer/src/lib.rs
index 589568a51d..465d994866 100644
--- a/beacon_node/execution_layer/src/lib.rs
+++ b/beacon_node/execution_layer/src/lib.rs
@@ -5,6 +5,7 @@ use slog::Logger;
 
 mod engine_api;
 mod engines;
+pub mod test_utils;
 
 #[derive(Debug)]
 pub enum Error {
diff --git a/beacon_node/execution_layer/src/test_utils/mod.rs b/beacon_node/execution_layer/src/test_utils/mod.rs
new file mode 100644
index 0000000000..1b28d1199a
--- /dev/null
+++ b/beacon_node/execution_layer/src/test_utils/mod.rs
@@ -0,0 +1,175 @@
+use bytes::Bytes;
+use environment::null_logger;
+use serde::{Deserialize, Serialize};
+use slog::{info, Logger};
+use std::future::Future;
+use std::marker::PhantomData;
+use std::net::{Ipv4Addr, SocketAddr, SocketAddrV4};
+use std::sync::Arc;
+use tokio::sync::{oneshot, RwLock};
+use types::EthSpec;
+use warp::Filter;
+
+pub struct MockServer {
+    _shutdown_tx: oneshot::Sender<()>,
+    listen_socket_addr: SocketAddr,
+    last_echo_request: Arc<RwLock<Option<Bytes>>>,
+}
+
+impl MockServer {
+    pub fn unit_testing<T: EthSpec>() -> Self {
+        let last_echo_request = Arc::new(RwLock::new(None));
+
+        let ctx: Arc<Context<T>> = Arc::new(Context {
+            config: <_>::default(),
+            log: null_logger().unwrap(),
+            last_echo_request: last_echo_request.clone(),
+            _phantom: PhantomData,
+        });
+
+        let (shutdown_tx, shutdown_rx) = oneshot::channel();
+
+        let shutdown_future = async {
+            // Ignore the result from the channel, shut down regardless.
+            let _ = shutdown_rx.await;
+        };
+
+        let (listen_socket_addr, server_future) = serve(ctx, shutdown_future).unwrap();
+
+        tokio::spawn(server_future);
+
+        Self {
+            _shutdown_tx: shutdown_tx,
+            listen_socket_addr,
+            last_echo_request,
+        }
+    }
+
+    pub fn url(&self) -> String {
+        format!(
+            "http://{}:{}",
+            self.listen_socket_addr.ip(),
+            self.listen_socket_addr.port()
+        )
+    }
+
+    pub async fn last_echo_request(&self) -> Bytes {
+        self.last_echo_request
+            .write()
+            .await
+            .take()
+            .expect("last echo request is none")
+    }
+}
+
+#[derive(Debug)]
+pub enum Error {
+    Warp(warp::Error),
+    Other(String),
+}
+
+impl From<warp::Error> for Error {
+    fn from(e: warp::Error) -> Self {
+        Error::Warp(e)
+    }
+}
+
+impl From<String> for Error {
+    fn from(e: String) -> Self {
+        Error::Other(e)
+    }
+}
+
+/// A wrapper around all the items required to spawn the HTTP server.
+///
+/// The server will gracefully handle the case where any fields are `None`.
+pub struct Context<T> {
+    pub config: Config,
+    pub log: Logger,
+    pub last_echo_request: Arc<RwLock<Option<Bytes>>>,
+    pub _phantom: PhantomData<T>,
+}
+
+/// Configuration for the HTTP server.
+#[derive(PartialEq, Debug, Clone, Serialize, Deserialize)]
+pub struct Config {
+    pub listen_addr: Ipv4Addr,
+    pub listen_port: u16,
+    pub allow_origin: Option<String>,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Self {
+            listen_addr: Ipv4Addr::new(127, 0, 0, 1),
+            listen_port: 0,
+            allow_origin: None,
+        }
+    }
+}
+
+/// Creates a server that will serve requests using information from `ctx`.
+///
+/// The server will shut down gracefully when the `shutdown` future resolves.
+///
+/// ## Returns
+///
+/// This function will bind the server to the provided address and then return a tuple of:
+///
+/// - `SocketAddr`: the address that the HTTP server will listen on.
+/// - `Future`: the actual server future that will need to be awaited.
+///
+/// ## Errors
+///
+/// Returns an error if the server is unable to bind or there is another error during
+/// configuration.
+pub fn serve<T: EthSpec>(
+    ctx: Arc<Context<T>>,
+    shutdown: impl Future<Output = ()> + Send + Sync + 'static,
+) -> Result<(SocketAddr, impl Future<Output = ()>), Error> {
+    let config = &ctx.config;
+    let log = ctx.log.clone();
+
+    // Configure CORS.
+    let cors_builder = {
+        let builder = warp::cors()
+            .allow_method("GET")
+            .allow_headers(vec!["Content-Type"]);
+
+        warp_utils::cors::set_builder_origins(
+            builder,
+            config.allow_origin.as_deref(),
+            (config.listen_addr, config.listen_port),
+        )?
+    };
+
+    let inner_ctx = ctx.clone();
+    let routes = warp::post()
+        .and(warp::path("echo"))
+        .and(warp::body::bytes())
+        .and(warp::any().map(move || inner_ctx.clone()))
+        .and_then(|bytes: Bytes, ctx: Arc<Context<T>>| async move {
+            *ctx.last_echo_request.write().await = Some(bytes.clone());
+            Ok::<_, warp::reject::Rejection>(
+                warp::http::Response::builder().status(200).body(bytes),
+            )
+        })
+        // Add a `Server` header.
+        .map(|reply| warp::reply::with_header(reply, "Server", "lighthouse-mock-execution-client"))
+        .with(cors_builder.build());
+
+    let (listening_socket, server) = warp::serve(routes).try_bind_with_graceful_shutdown(
+        SocketAddrV4::new(config.listen_addr, config.listen_port),
+        async {
+            shutdown.await;
+        },
+    )?;
+
+    info!(
+        log,
+        "Metrics HTTP server started";
+        "listen_address" => listening_socket.to_string(),
+    );
+
+    Ok((listening_socket, server))
+}