diff --git a/Cargo.lock b/Cargo.lock
index f5c4c13..831389d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2,10 +2,356 @@
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 version = 3
 
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diff --git a/core-rpc/Cargo.toml b/core-rpc/Cargo.toml
index 434b6ea..a8167a5 100644
--- a/core-rpc/Cargo.toml
+++ b/core-rpc/Cargo.toml
@@ -3,6 +3,5 @@ name = "core-rpc"
 version = "0.1.0"
 edition = "2021"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
 [dependencies]
+curl = "0.4.44"
diff --git a/esplora-api/Cargo.toml b/esplora-api/Cargo.toml
index bcbce95..3f4fc1d 100644
--- a/esplora-api/Cargo.toml
+++ b/esplora-api/Cargo.toml
@@ -3,6 +3,7 @@ name = "esplora-api"
 version = "0.1.0"
 edition = "2021"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
 [dependencies]
+curl = "0.4.44"
+serde_json = "1.0"
+serde = "1.0"
diff --git a/esplora-api/src/lib.rs b/esplora-api/src/lib.rs
index 7d12d9a..f5e4b62 100644
--- a/esplora-api/src/lib.rs
+++ b/esplora-api/src/lib.rs
@@ -1,14 +1,63 @@
-pub fn add(left: usize, right: usize) -> usize {
-    left + right
+//! Esplora API
+//!
+//! Author: Vincenzo Palazzo <vincenzopalazzo@member.fsf.org>
+use std::io;
+
+use curl::easy::Easy;
+use serde_json as json;
+
+pub struct EsploraAPI {
+    base_url: String,
+}
+
+impl EsploraAPI {
+    /// Create a new instance of the esplora API client.
+    pub fn new(url: &str) -> io::Result<Self> {
+        Ok(Self {
+            base_url: url.to_owned(),
+        })
+    }
+
+    pub fn raw_call(&self, addons: &str) -> io::Result<Vec<u8>> {
+        let mut easy = Easy::new();
+        let mut body = Vec::new();
+        easy.url(&format!("{}/{addons}", self.base_url))?;
+
+        {
+            let mut transfer = easy.transfer();
+            transfer.write_function(|data| {
+                body.extend_from_slice(data);
+                Ok(data.len())
+            })?;
+
+            transfer.perform()?;
+        }
+        Ok(body)
+    }
+
+    // perform a generic call
+    pub fn call<D: serde::de::DeserializeOwned>(&self, addons: &str) -> io::Result<D> {
+        let body = self.raw_call(addons)?;
+        let parsed_json: D = json::from_slice(&body)?;
+        Ok(parsed_json)
+    }
 }
 
 #[cfg(test)]
 mod tests {
+    use std::io;
+
     use super::*;
 
     #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
+    fn test_tip() -> io::Result<()> {
+        let api = EsploraAPI::new("https://blockstream.info/api")?;
+        let hash = api.raw_call("blocks/tip/hash")?;
+        let hash = String::from_utf8(hash).unwrap();
+        assert_eq!(
+            hash,
+            "0000000000000000000099819a9e23a5068a2a6f0e842e4f9568f53ede446300"
+        );
+        Ok(())
     }
 }