diff --git a/Cargo.lock b/Cargo.lock
index 64ddf65391..faaeaa4c86 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2061,6 +2061,23 @@ version = "2.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f7531096570974c3a9dcf9e4b8e1cede1ec26cf5046219fb3b9d897503b9be59"
 
+[[package]]
+name = "execution_layer"
+version = "0.1.0"
+dependencies = [
+ "async-trait",
+ "eth1",
+ "eth2_serde_utils 0.1.0",
+ "futures",
+ "reqwest",
+ "sensitive_url",
+ "serde",
+ "serde_json",
+ "slog",
+ "tokio",
+ "types",
+]
+
 [[package]]
 name = "exit-future"
 version = "0.2.0"
diff --git a/Cargo.toml b/Cargo.toml
index ab0cb15dc2..f8c9a41395 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,6 +7,7 @@ members = [
     "beacon_node/client",
     "beacon_node/eth1",
     "beacon_node/eth2_libp2p",
+    "beacon_node/execution_layer",
     "beacon_node/http_api",
     "beacon_node/http_metrics",
     "beacon_node/network",
diff --git a/beacon_node/execution_layer/Cargo.toml b/beacon_node/execution_layer/Cargo.toml
new file mode 100644
index 0000000000..7883d02caa
--- /dev/null
+++ b/beacon_node/execution_layer/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "execution_layer"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+types = { path = "../../consensus/types"}
+tokio = { version = "1.10.0", features = ["full"] }
+async-trait = "0.1.51"
+slog = "2.5.2"
+futures = "0.3.7"
+sensitive_url = { path = "../../common/sensitive_url" }
+reqwest = { version = "0.11.0", features = ["json","stream"] }
+eth2_serde_utils = { path = "../../consensus/serde_utils" }
+serde_json = "1.0.58"
+serde = { version = "1.0.116", features = ["derive"] }
+eth1 = { path = "../eth1" }
diff --git a/beacon_node/execution_layer/src/engine_api.rs b/beacon_node/execution_layer/src/engine_api.rs
new file mode 100644
index 0000000000..84b5b6c8b3
--- /dev/null
+++ b/beacon_node/execution_layer/src/engine_api.rs
@@ -0,0 +1,35 @@
+use async_trait::async_trait;
+use eth1::http::RpcError;
+
+pub use types::{Address, Hash256};
+
+pub mod http;
+
+pub type PayloadId = u64;
+
+#[derive(Debug)]
+pub enum Error {
+    Reqwest(reqwest::Error),
+    BadResponse(String),
+    RequestFailed(String),
+    JsonRpc(RpcError),
+}
+
+impl From<reqwest::Error> for Error {
+    fn from(e: reqwest::Error) -> Self {
+        Error::Reqwest(e)
+    }
+}
+
+#[async_trait]
+pub trait EngineApi {
+    async fn upcheck(&self) -> Result<(), Error>;
+
+    async fn prepare_payload(
+        &self,
+        parent_hash: Hash256,
+        timestamp: u64,
+        random: Hash256,
+        fee_recipient: Address,
+    ) -> Result<PayloadId, Error>;
+}
diff --git a/beacon_node/execution_layer/src/engine_api/http.rs b/beacon_node/execution_layer/src/engine_api/http.rs
new file mode 100644
index 0000000000..6ba1bd1dbb
--- /dev/null
+++ b/beacon_node/execution_layer/src/engine_api/http.rs
@@ -0,0 +1,73 @@
+use super::*;
+use async_trait::async_trait;
+use eth1::http::{hex_to_u64_be, response_result_or_error, send_rpc_request};
+pub use reqwest::Client;
+use sensitive_url::SensitiveUrl;
+use serde::{Deserialize, Serialize};
+use serde_json::json;
+use std::time::Duration;
+
+const ENGINE_PREPARE_PAYLOAD: &str = "engine_preparePayload";
+const ENGINE_PREPARE_PAYLOAD_TIMEOUT: Duration = Duration::from_millis(500);
+
+pub struct HttpJsonRpc {
+    pub client: Client,
+    pub url: SensitiveUrl,
+}
+
+impl HttpJsonRpc {
+    pub fn new(url: SensitiveUrl) -> Result<Self, Error> {
+        Ok(Self {
+            client: Client::builder().build()?,
+            url,
+        })
+    }
+}
+
+#[async_trait]
+impl EngineApi for HttpJsonRpc {
+    async fn upcheck(&self) -> Result<(), Error> {
+        todo!()
+    }
+
+    async fn prepare_payload(
+        &self,
+        parent_hash: Hash256,
+        timestamp: u64,
+        random: Hash256,
+        fee_recipient: Address,
+    ) -> Result<PayloadId, Error> {
+        let params = json!([PreparePayloadRequest {
+            parent_hash,
+            timestamp,
+            random,
+            fee_recipient
+        }]);
+
+        let response_body = send_rpc_request(
+            &self.url,
+            ENGINE_PREPARE_PAYLOAD,
+            params,
+            ENGINE_PREPARE_PAYLOAD_TIMEOUT,
+        )
+        .await
+        .map_err(Error::RequestFailed)?;
+
+        let result = response_result_or_error(&response_body).map_err(Error::JsonRpc)?;
+        let string = result
+            .as_str()
+            .ok_or(Error::BadResponse("data was not string".to_string()))?;
+
+        hex_to_u64_be(string).map_err(Error::BadResponse)
+    }
+}
+
+#[derive(Debug, PartialEq, Serialize, Deserialize)]
+#[serde(rename = "camelCase")]
+struct PreparePayloadRequest {
+    parent_hash: Hash256,
+    #[serde(with = "eth2_serde_utils::u64_hex_be")]
+    timestamp: u64,
+    random: Hash256,
+    fee_recipient: Address,
+}
diff --git a/beacon_node/execution_layer/src/engines.rs b/beacon_node/execution_layer/src/engines.rs
new file mode 100644
index 0000000000..f3bd72197b
--- /dev/null
+++ b/beacon_node/execution_layer/src/engines.rs
@@ -0,0 +1,159 @@
+use crate::engine_api::{EngineApi, Error as EngineApiError};
+use futures::future::join_all;
+use slog::{crit, error, info, warn, Logger};
+use std::future::Future;
+use tokio::sync::RwLock;
+
+#[derive(Copy, Clone, PartialEq)]
+enum EngineState {
+    Online,
+    Offline,
+}
+
+impl EngineState {
+    fn set_online(&mut self) {
+        *self = EngineState::Online
+    }
+
+    fn set_offline(&mut self) {
+        *self = EngineState::Offline
+    }
+
+    fn is_online(&self) -> bool {
+        *self == EngineState::Online
+    }
+
+    fn is_offline(&self) -> bool {
+        *self == EngineState::Offline
+    }
+}
+
+pub struct Engine<T> {
+    pub id: String,
+    pub api: T,
+    state: RwLock<EngineState>,
+}
+
+impl<T> Engine<T> {
+    pub fn new(id: String, api: T) -> Self {
+        Self {
+            id,
+            api,
+            state: RwLock::new(EngineState::Offline),
+        }
+    }
+}
+
+pub struct Engines<T> {
+    pub engines: Vec<Engine<T>>,
+    pub log: Logger,
+}
+
+#[derive(Debug)]
+pub enum EngineError {
+    Offline { id: String },
+    Api { id: String, error: EngineApiError },
+}
+
+impl<T: EngineApi> Engines<T> {
+    async fn upcheck_offline(&self) {
+        let upcheck_futures = self.engines.iter().map(|engine| async move {
+            let mut state = engine.state.write().await;
+            if state.is_offline() {
+                match engine.api.upcheck().await {
+                    Ok(()) => {
+                        info!(
+                            self.log,
+                            "Execution engine online";
+                            "id" => &engine.id
+                        );
+                        state.set_online()
+                    }
+                    Err(e) => {
+                        warn!(
+                            self.log,
+                            "Execution engine offline";
+                            "error" => ?e,
+                            "id" => &engine.id
+                        )
+                    }
+                }
+            }
+            *state
+        });
+
+        let num_online = join_all(upcheck_futures)
+            .await
+            .into_iter()
+            .filter(|state: &EngineState| state.is_online())
+            .count();
+
+        if num_online == 0 {
+            crit!(
+                self.log,
+                "No execution engines online";
+            )
+        }
+    }
+
+    pub async fn first_success<'a, F, G, H>(&'a self, func: F) -> Result<H, Vec<EngineError>>
+    where
+        F: Fn(&'a Engine<T>) -> G + Copy,
+        G: Future<Output = Result<H, EngineApiError>>,
+    {
+        match self.first_success_without_retry(func).await {
+            Ok(result) => Ok(result),
+            Err(mut first_errors) => {
+                // Try to recover some nodes.
+                self.upcheck_offline().await;
+                // Retry the call on all nodes.
+                match self.first_success_without_retry(func).await {
+                    Ok(result) => Ok(result),
+                    Err(second_errors) => {
+                        first_errors.extend(second_errors);
+                        Err(first_errors)
+                    }
+                }
+            }
+        }
+    }
+
+    async fn first_success_without_retry<'a, F, G, H>(
+        &'a self,
+        func: F,
+    ) -> Result<H, Vec<EngineError>>
+    where
+        F: Fn(&'a Engine<T>) -> G,
+        G: Future<Output = Result<H, EngineApiError>>,
+    {
+        let mut errors = vec![];
+
+        for engine in &self.engines {
+            let engine_online = engine.state.read().await.is_online();
+            if engine_online {
+                match func(engine).await {
+                    Ok(result) => return Ok(result),
+                    Err(error) => {
+                        error!(
+                            self.log,
+                            "Execution engine call failed";
+                            "error" => ?error,
+                            "id" => &engine.id
+                        );
+                        engine.state.write().await.set_offline();
+                        errors.push(EngineError::Api {
+                            id: engine.id.clone(),
+                            error,
+                        })
+                    }
+                }
+            } else {
+                errors.push(EngineError::Offline {
+                    id: engine.id.clone(),
+                })
+            }
+        }
+
+        Err(errors)
+    }
+}
diff --git a/beacon_node/execution_layer/src/lib.rs b/beacon_node/execution_layer/src/lib.rs
new file mode 100644
index 0000000000..589568a51d
--- /dev/null
+++ b/beacon_node/execution_layer/src/lib.rs
@@ -0,0 +1,67 @@
+use engine_api::{http::HttpJsonRpc, Error as ApiError, *};
+use engines::{Engine, EngineError, Engines};
+use sensitive_url::SensitiveUrl;
+use slog::Logger;
+
+mod engine_api;
+mod engines;
+
+#[derive(Debug)]
+pub enum Error {
+    ApiError(ApiError),
+    EngineErrors(Vec<EngineError>),
+}
+
+impl From<ApiError> for Error {
+    fn from(e: ApiError) -> Self {
+        Error::ApiError(e)
+    }
+}
+
+pub struct ExecutionLayer<T> {
+    engines: Engines<T>,
+}
+
+impl ExecutionLayer<HttpJsonRpc> {
+    pub fn from_urls(urls: Vec<SensitiveUrl>, log: Logger) -> Result<Self, Error> {
+        let engines = urls
+            .into_iter()
+            .map(|url| {
+                let id = url.to_string();
+                let api = HttpJsonRpc::new(url)?;
+                Ok(Engine::new(id, api))
+            })
+            .collect::<Result<_, ApiError>>()?;
+
+        Ok(Self {
+            engines: Engines { engines, log },
+        })
+    }
+}
+
+impl<T: EngineApi> ExecutionLayer<T> {
+    pub async fn prepare_payload(
+        &self,
+        parent_hash: Hash256,
+        timestamp: u64,
+        random: Hash256,
+        fee_recipient: Address,
+    ) -> Result<PayloadId, Error> {
+        self.engines
+            .first_success(|engine| {
+                engine
+                    .api
+                    .prepare_payload(parent_hash, timestamp, random, fee_recipient)
+            })
+            .await
+            .map_err(Error::EngineErrors)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}