diff --git a/cli/src/main.rs b/cli/src/main.rs
index dcb6f13..eb5a12d 100644
--- a/cli/src/main.rs
+++ b/cli/src/main.rs
@@ -3,7 +3,7 @@ use std::{sync::Arc, time::Duration};
 use clap::Parser;
 use dirs::home_dir;
 use eyre::Result;
-use tokio::time::sleep;
+use tokio::{sync::Mutex, time::sleep};
 
 use client::{rpc::Rpc, Client};
 use config::{networks, Config};
@@ -23,13 +23,16 @@ async fn main() -> Result<()> {
     let mut client = Client::new(Arc::new(config)).await?;
     client.sync().await?;
 
-    let mut rpc = Rpc::new(Arc::new(client), cli.port.unwrap_or(8545));
+    let client = Arc::new(Mutex::new(client));
+
+    let mut rpc = Rpc::new(client.clone(), cli.port.unwrap_or(8545));
     let addr = rpc.start().await?;
     println!("started rpc at: {}", addr);
 
-    sleep(Duration::from_secs(300)).await;
-
-    Ok(())
+    loop {
+        sleep(Duration::from_secs(10)).await;
+        client.lock().await.advance().await?
+    }
 }
 
 #[derive(Parser)]
diff --git a/client/src/client.rs b/client/src/client.rs
index 71b6dbe..3620fb1 100644
--- a/client/src/client.rs
+++ b/client/src/client.rs
@@ -36,6 +36,10 @@ impl Client {
         self.consensus.sync().await
     }
 
+    pub async fn advance(&mut self) -> Result<()> {
+        self.consensus.advance().await
+    }
+
     pub async fn call(&self, to: &Address, calldata: &Vec<u8>, value: U256) -> Result<Vec<u8>> {
         let payload = self.consensus.get_execution_payload().await?;
         let mut evm = Evm::new(self.execution.clone(), payload);
diff --git a/client/src/rpc.rs b/client/src/rpc.rs
index f421114..7790338 100644
--- a/client/src/rpc.rs
+++ b/client/src/rpc.rs
@@ -5,6 +5,7 @@ use ethers::{
 use eyre::Result;
 use serde::{Deserialize, Serialize};
 use std::{fmt::Display, net::SocketAddr, str::FromStr, sync::Arc};
+use tokio::sync::Mutex;
 
 use jsonrpsee::{
     core::{async_trait, Error},
@@ -17,13 +18,13 @@ use common::utils::{hex_str_to_bytes, u64_to_hex_string};
 use super::Client;
 
 pub struct Rpc {
-    client: Arc<Client>,
+    client: Arc<Mutex<Client>>,
     handle: Option<HttpServerHandle>,
     port: u16,
 }
 
 impl Rpc {
-    pub fn new(client: Arc<Client>, port: u16) -> Self {
+    pub fn new(client: Arc<Mutex<Client>>, port: u16) -> Self {
         Rpc {
             client,
             handle: None,
@@ -55,7 +56,7 @@ trait EthRpc {
     #[method(name = "estimateGas")]
     async fn estimate_gas(&self, opts: CallOpts) -> Result<String, Error>;
     #[method(name = "chainId")]
-    fn chain_id(&self) -> Result<String, Error>;
+    async fn chain_id(&self) -> Result<String, Error>;
     #[method(name = "gasPrice")]
     async fn gas_price(&self) -> Result<String, Error>;
     #[method(name = "maxPriorityFeePerGas")]
@@ -65,7 +66,7 @@ trait EthRpc {
 }
 
 struct RpcInner {
-    client: Arc<Client>,
+    client: Arc<Mutex<Client>>,
     port: u16,
 }
 
@@ -75,7 +76,8 @@ impl EthRpcServer for RpcInner {
         match block {
             "latest" => {
                 let address = convert_err(Address::from_str(address))?;
-                let balance = convert_err(self.client.get_balance(&address).await)?;
+                let client = self.client.lock().await;
+                let balance = convert_err(client.get_balance(&address).await)?;
 
                 Ok(balance.encode_hex())
             }
@@ -87,7 +89,8 @@ impl EthRpcServer for RpcInner {
         match block {
             "latest" => {
                 let address = convert_err(Address::from_str(address))?;
-                let nonce = convert_err(self.client.get_nonce(&address).await)?;
+                let client = self.client.lock().await;
+                let nonce = convert_err(client.get_nonce(&address).await)?;
 
                 Ok(nonce.encode_hex())
             }
@@ -99,7 +102,8 @@ impl EthRpcServer for RpcInner {
         match block {
             "latest" => {
                 let address = convert_err(Address::from_str(address))?;
-                let code = convert_err(self.client.get_code(&address).await)?;
+                let client = self.client.lock().await;
+                let code = convert_err(client.get_code(&address).await)?;
 
                 Ok(hex::encode(code))
             }
@@ -117,7 +121,8 @@ impl EthRpcServer for RpcInner {
                     16,
                 ))?;
 
-                let res = convert_err(self.client.call(&to, &data, value).await)?;
+                let client = self.client.lock().await;
+                let res = convert_err(client.call(&to, &data, value).await)?;
                 Ok(hex::encode(res))
             }
             _ => Err(Error::Custom("Invalid Block Number".to_string())),
@@ -132,27 +137,32 @@ impl EthRpcServer for RpcInner {
             16,
         ))?;
 
-        let gas = convert_err(self.client.estimate_gas(&to, &data, value).await)?;
+        let client = self.client.lock().await;
+        let gas = convert_err(client.estimate_gas(&to, &data, value).await)?;
         Ok(u64_to_hex_string(gas))
     }
 
-    fn chain_id(&self) -> Result<String, Error> {
-        let id = self.client.chain_id();
+    async fn chain_id(&self) -> Result<String, Error> {
+        let client = self.client.lock().await;
+        let id = client.chain_id();
         Ok(u64_to_hex_string(id))
     }
 
     async fn gas_price(&self) -> Result<String, Error> {
-        let gas_price = convert_err(self.client.get_gas_price().await)?;
+        let client = self.client.lock().await;
+        let gas_price = convert_err(client.get_gas_price().await)?;
         Ok(gas_price.encode_hex())
     }
 
     async fn max_priority_fee_per_gas(&self) -> Result<String, Error> {
-        let tip = convert_err(self.client.get_priority_fee().await)?;
+        let client = self.client.lock().await;
+        let tip = convert_err(client.get_priority_fee().await)?;
         Ok(tip.encode_hex())
     }
 
     async fn block_number(&self) -> Result<String, Error> {
-        let num = convert_err(self.client.get_block_number().await)?;
+        let client = self.client.lock().await;
+        let num = convert_err(client.get_block_number().await)?;
         Ok(u64_to_hex_string(num))
     }
 }
diff --git a/config/src/networks.rs b/config/src/networks.rs
index 8dc0dcb..849ecd9 100644
--- a/config/src/networks.rs
+++ b/config/src/networks.rs
@@ -11,10 +11,10 @@ pub fn goerli() -> Config {
             )
             .unwrap(),
             checkpoint: hex_str_to_bytes(
-                "0x172128eadf1da46467f4d6a822206698e2d3f957af117dd650954780d680dc99",
+                "0x1e591af1e90f2db918b2a132991c7c2ee9a4ab26da496bd6e71e4f0bd65ea870",
             )
             .unwrap(),
-            consensus_rpc: "http://testing.prater.beacon-api.nimbus.team".to_string(),
+            consensus_rpc: "http://34.207.158.131:5052".to_string(),
             execution_rpc:
                 "https://eth-goerli.g.alchemy.com:443/v2/o_8Qa9kgwDPf9G8sroyQ-uQtyhyWa3ao"
                     .to_string(),
diff --git a/consensus/src/consensus.rs b/consensus/src/consensus.rs
index 7f1dcd6..67b60be 100644
--- a/consensus/src/consensus.rs
+++ b/consensus/src/consensus.rs
@@ -1,3 +1,4 @@
+use std::cmp;
 use std::sync::Arc;
 
 use blst::min_pk::{PublicKey, Signature};
@@ -20,9 +21,12 @@ pub struct ConsensusClient {
 
 #[derive(Debug)]
 struct Store {
-    header: Header,
+    finalized_header: Header,
     current_sync_committee: SyncCommittee,
     next_sync_committee: Option<SyncCommittee>,
+    optimistic_header: Header,
+    previous_max_active_participants: u64,
+    current_max_active_participants: u64,
 }
 
 impl ConsensusClient {
@@ -50,19 +54,22 @@ impl ConsensusClient {
         }
 
         let store = Store {
-            header: bootstrap.header,
+            finalized_header: bootstrap.header.clone(),
             current_sync_committee: bootstrap.current_sync_committee,
             next_sync_committee: None,
+            optimistic_header: bootstrap.header,
+            previous_max_active_participants: 0,
+            current_max_active_participants: 0,
         };
 
         Ok(ConsensusClient { rpc, store, config })
     }
 
     pub async fn get_execution_payload(&self) -> Result<ExecutionPayload> {
-        let slot = self.store.header.slot;
+        let slot = self.store.optimistic_header.slot;
         let mut block = self.rpc.get_block(slot).await?.clone();
         let block_hash = block.hash_tree_root()?;
-        let verified_block_hash = self.store.header.clone().hash_tree_root()?;
+        let verified_block_hash = self.store.optimistic_header.clone().hash_tree_root()?;
 
         if verified_block_hash != block_hash {
             Err(eyre::eyre!("Block Root Mismatch"))
@@ -72,11 +79,11 @@ impl ConsensusClient {
     }
 
     pub fn get_head(&self) -> &Header {
-        &self.store.header
+        &self.store.optimistic_header
     }
 
     pub async fn sync(&mut self) -> Result<()> {
-        let current_period = calc_sync_period(self.store.header.slot);
+        let current_period = calc_sync_period(self.store.finalized_header.slot);
         let updates = self.rpc.get_updates(current_period).await?;
 
         for mut update in updates {
@@ -85,32 +92,34 @@ impl ConsensusClient {
         }
 
         let finality_update = self.rpc.get_finality_update().await?;
-        let mut finality_update_generic = Update {
-            attested_header: finality_update.attested_header,
-            next_sync_committee: None,
-            next_sync_committee_branch: Vec::new(),
-            finalized_header: finality_update.finalized_header,
-            finality_branch: finality_update.finality_branch,
-            sync_aggregate: finality_update.sync_aggregate,
-            signature_slot: finality_update.signature_slot,
-        };
+        self.verify_finality_update(&finality_update)?;
+        self.apply_finality_update(&finality_update);
 
-        self.verify_update(&mut finality_update_generic)?;
-        self.apply_update(&finality_update_generic);
+        let optimistic_update = self.rpc.get_optimistic_update().await?;
+        self.verify_optimistic_update(&optimistic_update)?;
+        self.apply_optimistic_update(&optimistic_update);
 
-        self.rpc.get_block(self.store.header.slot).await?;
+        Ok(())
+    }
+
+    pub async fn advance(&mut self) -> Result<()> {
+        let finality_update = self.rpc.get_finality_update().await?;
+        self.verify_finality_update(&finality_update)?;
+        self.apply_finality_update(&finality_update);
+
+        let optimistic_update = self.rpc.get_optimistic_update().await?;
+        self.verify_optimistic_update(&optimistic_update)?;
+        self.apply_optimistic_update(&optimistic_update);
 
         Ok(())
     }
 
     fn verify_update(&mut self, update: &mut Update) -> Result<()> {
-        let current_slot = self.store.header.slot;
-        let update_slot = update.finalized_header.slot;
+        let store_period = calc_sync_period(self.store.finalized_header.slot);
+        let update_signature_period = calc_sync_period(update.signature_slot);
 
-        let current_period = calc_sync_period(current_slot);
-        let update_period = calc_sync_period(update_slot);
-
-        if !(update_period == current_period + 1 || update_period == current_period) {
+        if !(update_signature_period == store_period + 1 || update_signature_period == store_period)
+        {
             return Err(eyre::eyre!("Invalid Update"));
         }
 
@@ -130,26 +139,25 @@ impl ConsensusClient {
             return Err(eyre::eyre!("Invalid Update"));
         }
 
-        if update.next_sync_committee.is_some() {
-            let next_committee_branch_valid = is_next_committee_proof_valid(
-                &update.attested_header,
-                &mut update.next_sync_committee.clone().unwrap(),
-                &update.next_sync_committee_branch,
-            );
+        let next_committee_branch_valid = is_next_committee_proof_valid(
+            &update.attested_header,
+            &mut update.next_sync_committee,
+            &update.next_sync_committee_branch,
+        );
 
-            if !next_committee_branch_valid {
-                return Err(eyre::eyre!("Invalid Update"));
-            }
+        if !next_committee_branch_valid {
+            return Err(eyre::eyre!("Invalid Update"));
         }
 
-        let sync_committee = if current_period == update_period {
+        let sync_committee = if store_period == update_signature_period {
             &self.store.current_sync_committee
         } else {
             self.store.next_sync_committee.as_ref().unwrap()
         };
 
         let pks =
-            get_participating_keys(sync_committee, &update.sync_aggregate.sync_committee_bits)?;
+            get_participating_keys(&sync_committee, &update.sync_aggregate.sync_committee_bits)?;
+
         let pks: Vec<&PublicKey> = pks.iter().map(|pk| pk).collect();
 
         let committee_quorum = pks.len() > 1;
@@ -169,20 +177,152 @@ impl ConsensusClient {
         Ok(())
     }
 
-    fn apply_update(&mut self, update: &Update) {
-        let current_period = calc_sync_period(self.store.header.slot);
-        let update_period = calc_sync_period(update.finalized_header.slot);
+    fn verify_finality_update(&self, update: &FinalityUpdate) -> Result<()> {
+        let store_period = calc_sync_period(self.store.finalized_header.slot);
+        let update_signature_period = calc_sync_period(update.signature_slot);
 
-        self.store.header = update.finalized_header.clone();
+        if !(update_signature_period == store_period + 1 || update_signature_period == store_period)
+        {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        if !(update.signature_slot > update.attested_header.slot
+            && update.attested_header.slot > update.finalized_header.slot)
+        {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        let finality_branch_valid = is_finality_proof_valid(
+            &update.attested_header,
+            &mut update.finalized_header.clone(),
+            &update.finality_branch,
+        );
+
+        if !(finality_branch_valid) {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        let sync_committee = &self.store.current_sync_committee;
+
+        let pks =
+            get_participating_keys(&sync_committee, &update.sync_aggregate.sync_committee_bits)?;
+
+        let pks: Vec<&PublicKey> = pks.iter().map(|pk| pk).collect();
+
+        let committee_quorum = pks.len() > 1;
+        if !committee_quorum {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        let header_root =
+            bytes_to_bytes32(update.attested_header.clone().hash_tree_root()?.as_bytes());
+        let signing_root = self.compute_committee_sign_root(header_root, update.signature_slot)?;
+        let sig = &update.sync_aggregate.sync_committee_signature;
+        let is_valid_sig = is_aggregate_valid(sig, signing_root.as_bytes(), &pks);
+
+        if !is_valid_sig {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        Ok(())
+    }
+
+    fn verify_optimistic_update(&self, update: &OptimisticUpdate) -> Result<()> {
+        let store_period = calc_sync_period(self.store.finalized_header.slot);
+        let update_signature_period = calc_sync_period(update.signature_slot);
+
+        if !(update_signature_period == store_period + 1 || update_signature_period == store_period)
+        {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        if !(update.signature_slot > update.attested_header.slot) {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        let sync_committee = &self.store.current_sync_committee;
+
+        let pks =
+            get_participating_keys(&sync_committee, &update.sync_aggregate.sync_committee_bits)?;
+
+        let pks: Vec<&PublicKey> = pks.iter().map(|pk| pk).collect();
+
+        let committee_quorum = pks.len() > 1;
+        if !committee_quorum {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        let header_root =
+            bytes_to_bytes32(update.attested_header.clone().hash_tree_root()?.as_bytes());
+        let signing_root = self.compute_committee_sign_root(header_root, update.signature_slot)?;
+        let sig = &update.sync_aggregate.sync_committee_signature;
+        let is_valid_sig = is_aggregate_valid(sig, signing_root.as_bytes(), &pks);
+
+        if !is_valid_sig {
+            return Err(eyre::eyre!("Invalid Update"));
+        }
+
+        Ok(())
+    }
+
+    fn apply_update(&mut self, update: &Update) {
+        let store_period = calc_sync_period(self.store.finalized_header.slot);
+        let update_signature_period = calc_sync_period(update.signature_slot);
+
+        self.store.finalized_header = update.finalized_header.clone();
 
         if self.store.next_sync_committee.is_none() {
-            self.store.next_sync_committee =
-                Some(update.next_sync_committee.as_ref().unwrap().clone());
-        } else if update_period == current_period + 1 {
+            self.store.next_sync_committee = Some(update.next_sync_committee.clone());
+        } else if update_signature_period == store_period + 1 {
             self.store.current_sync_committee =
                 self.store.next_sync_committee.as_ref().unwrap().clone();
-            self.store.next_sync_committee =
-                Some(update.next_sync_committee.as_ref().unwrap().clone());
+            self.store.next_sync_committee = Some(update.next_sync_committee.clone());
+        }
+
+        println!(
+            "applying update for slot: {}",
+            self.store.finalized_header.slot
+        );
+    }
+
+    fn apply_finality_update(&mut self, update: &FinalityUpdate) {
+        if self.store.finalized_header.slot != update.finalized_header.slot {
+            self.store.finalized_header = update.finalized_header.clone();
+            self.store.previous_max_active_participants =
+                self.store.current_max_active_participants;
+            self.store.current_max_active_participants =
+                get_bits(&update.sync_aggregate.sync_committee_bits);
+
+            println!(
+                "applying finality update for slot: {}",
+                self.store.finalized_header.slot
+            );
+        }
+
+        if self.store.finalized_header.slot > self.store.optimistic_header.slot {
+            self.store.optimistic_header = self.store.finalized_header.clone();
+        }
+    }
+
+    fn apply_optimistic_update(&mut self, update: &OptimisticUpdate) {
+        let votes = get_bits(&update.sync_aggregate.sync_committee_bits);
+        if votes > self.store.current_max_active_participants {
+            self.store.current_max_active_participants = votes;
+        }
+
+        let safety_theshhold = cmp::max(
+            self.store.current_max_active_participants,
+            self.store.previous_max_active_participants,
+        ) / 2;
+
+        if votes > safety_theshhold
+            && update.attested_header.slot > self.store.optimistic_header.slot
+        {
+            self.store.optimistic_header = update.attested_header.clone();
+            println!(
+                "applying optimistic update for slot: {}",
+                self.store.optimistic_header.slot
+            );
         }
     }
 
@@ -218,6 +358,17 @@ fn get_participating_keys(
     Ok(pks)
 }
 
+fn get_bits(bitfield: &Bitvector<512>) -> u64 {
+    let mut count = 0;
+    bitfield.iter().for_each(|bit| {
+        if bit == true {
+            count += 1;
+        }
+    });
+
+    count
+}
+
 fn is_aggregate_valid(sig_bytes: &SignatureBytes, msg: &[u8], pks: &[&PublicKey]) -> bool {
     let dst: &[u8] = b"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_";
     let sig_res = Signature::from_bytes(&sig_bytes);
diff --git a/consensus/src/rpc.rs b/consensus/src/rpc.rs
index f1f16a3..7fa0ef4 100644
--- a/consensus/src/rpc.rs
+++ b/consensus/src/rpc.rs
@@ -41,6 +41,15 @@ impl Rpc {
         Ok(res.data)
     }
 
+    pub async fn get_optimistic_update(&self) -> Result<OptimisticUpdate> {
+        let req = format!("{}/eth/v0/beacon/light_client/optimistic_update", self.rpc);
+        let res = reqwest::get(req)
+            .await?
+            .json::<OptimisticUpdateResponse>()
+            .await?;
+        Ok(res.data)
+    }
+
     pub async fn get_block(&self, slot: u64) -> Result<BeaconBlock> {
         let req = format!("{}/eth/v2/beacon/blocks/{}", self.rpc, slot);
         let res = reqwest::get(req)
@@ -71,6 +80,11 @@ struct FinalityUpdateResponse {
     data: FinalityUpdate,
 }
 
+#[derive(serde::Deserialize, Debug)]
+struct OptimisticUpdateResponse {
+    data: OptimisticUpdate,
+}
+
 #[derive(serde::Deserialize, Debug)]
 struct BootstrapResponse {
     data: BootstrapData,
diff --git a/consensus/src/types.rs b/consensus/src/types.rs
index 08e6c52..8f46cb3 100644
--- a/consensus/src/types.rs
+++ b/consensus/src/types.rs
@@ -130,7 +130,7 @@ pub struct Bootstrap {
 #[derive(serde::Deserialize, Debug, Clone)]
 pub struct Update {
     pub attested_header: Header,
-    pub next_sync_committee: Option<SyncCommittee>,
+    pub next_sync_committee: SyncCommittee,
     #[serde(deserialize_with = "branch_deserialize")]
     pub next_sync_committee_branch: Vec<Bytes32>,
     pub finalized_header: Header,
@@ -152,6 +152,14 @@ pub struct FinalityUpdate {
     pub signature_slot: u64,
 }
 
+#[derive(serde::Deserialize, Debug)]
+pub struct OptimisticUpdate {
+    pub attested_header: Header,
+    pub sync_aggregate: SyncAggregate,
+    #[serde(deserialize_with = "u64_deserialize")]
+    pub signature_slot: u64,
+}
+
 #[derive(serde::Deserialize, Debug, Clone, Default, SimpleSerialize)]
 pub struct Header {
     #[serde(deserialize_with = "u64_deserialize")]