diff --git a/ghost-crab-common/src/config.rs b/ghost-crab-common/src/config.rs
index 53cc945..d771be1 100644
--- a/ghost-crab-common/src/config.rs
+++ b/ghost-crab-common/src/config.rs
@@ -1,5 +1,9 @@
+use dotenvy::dotenv;
 use serde::Deserialize;
-use std::collections::HashMap;
+use serde_json::Error as SerdeError;
+use std::path::PathBuf;
+use std::{collections::HashMap, io::Error as IoError};
+use std::{env, fs};
 
 #[derive(Clone, Copy, Deserialize, Debug)]
 #[serde(rename_all = "lowercase")]
@@ -43,3 +47,67 @@ pub struct Config {
     pub networks: HashMap<String, String>,
     pub block_handlers: HashMap<String, BlockHandler>,
 }
+
+#[derive(Debug)]
+pub enum ConfigError {
+    FileNotFound(IoError),
+    CurrentDirNotFound(IoError),
+    InvalidConfig(SerdeError),
+    EnvVarNotFound(String),
+}
+
+impl std::fmt::Display for ConfigError {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
+        match self {
+            ConfigError::FileNotFound(error) => {
+                write!(formatter, "Config file not found: {}", error)
+            }
+            ConfigError::CurrentDirNotFound(error) => {
+                write!(formatter, "Current directory not found: {}", error)
+            }
+            ConfigError::InvalidConfig(error) => {
+                write!(formatter, "Invalid config format: {}", error)
+            }
+            ConfigError::EnvVarNotFound(var) => {
+                write!(formatter, "Environment variable not found: {}", var)
+            }
+        }
+    }
+}
+
+impl std::error::Error for ConfigError {}
+
+pub fn load() -> Result<Config, ConfigError> {
+    dotenv().ok();
+
+    let config_path = get_config_path()?;
+    let config_string = read_config_file(&config_path)?;
+    let mut config: Config = parse_config(&config_string)?;
+    replace_env_vars(&mut config)?;
+
+    Ok(config)
+}
+
+fn get_config_path() -> Result<PathBuf, ConfigError> {
+    let current_dir = env::current_dir().map_err(|error| ConfigError::CurrentDirNotFound(error))?;
+    Ok(current_dir.join("config.json"))
+}
+
+fn read_config_file(path: &PathBuf) -> Result<String, ConfigError> {
+    fs::read_to_string(path).map_err(|error| ConfigError::FileNotFound(error))
+}
+
+fn parse_config(config_string: &str) -> Result<Config, ConfigError> {
+    serde_json::from_str(config_string).map_err(|error| ConfigError::InvalidConfig(error))
+}
+
+fn replace_env_vars(config: &mut Config) -> Result<(), ConfigError> {
+    for (_key, value) in &mut config.networks {
+        if value.starts_with('$') {
+            *value = env::var(&value[1..])
+                .map_err(|_| ConfigError::EnvVarNotFound(value[1..].to_string()))?;
+        }
+    }
+
+    Ok(())
+}
diff --git a/ghost-crab-macros/src/lib.rs b/ghost-crab-macros/src/lib.rs
index ea0934b..2ed446d 100644
--- a/ghost-crab-macros/src/lib.rs
+++ b/ghost-crab-macros/src/lib.rs
@@ -1,9 +1,8 @@
 extern crate proc_macro;
-use ghost_crab_common::config::{Config, ExecutionMode};
+use ghost_crab_common::config::{self, ExecutionMode};
 use proc_macro::TokenStream;
 use proc_macro2::{Ident, Literal};
 use quote::{format_ident, quote};
-use std::fs;
 use syn::{parse_macro_input, ItemFn};
 
 #[proc_macro_attribute]
@@ -25,7 +24,7 @@ pub fn block_handler(metadata: TokenStream, input: TokenStream) -> TokenStream {
         panic!("The source is missing");
     }
 
-    let config = get_config();
+    let config = config::load().unwrap();
     let source = config.block_handlers.get(name).expect("Source not found.");
 
     let rpc_url = config.networks.get(&source.network).expect("RPC url not found for network");
@@ -83,14 +82,6 @@ pub fn block_handler(metadata: TokenStream, input: TokenStream) -> TokenStream {
     })
 }
 
-fn get_config() -> Config {
-    let current_dir = std::env::current_dir().expect("Current directory not found");
-    let config_json_path = current_dir.join("config.json");
-    let content = fs::read_to_string(config_json_path).expect("Error reading config file");
-    let config: Config = serde_json::from_str(&content).expect("Error parsing config file");
-    return config;
-}
-
 fn get_source_and_event(metadata: TokenStream) -> (String, Ident) {
     let metadata_string = metadata.to_string();
     let mut metadata_split = metadata_string.split('.');
@@ -137,7 +128,7 @@ fn get_context_identifier(parsed: ItemFn) -> Ident {
 
 fn create_handler(metadata: TokenStream, input: TokenStream, is_template: bool) -> TokenStream {
     let (name, event_name) = get_source_and_event(metadata);
-    let config = get_config();
+    let config = config::load().unwrap();
 
     let abi;
     let network;