diff --git a/src/session.rs b/src/session.rs
index 49e2b2f..98397f7 100644
--- a/src/session.rs
+++ b/src/session.rs
@@ -1,17 +1,20 @@
+use std::io;
 use std::{fs, path::PathBuf};
 
 use anyhow::Context;
 use axum::{extract::State, routing::post, Json, Router};
 use serde::{Deserialize, Serialize};
 use starknet::core::types::FieldElement;
+use thiserror::Error;
 use tokio::sync::mpsc::{channel, Receiver, Sender};
 use tower_http::cors::CorsLayer;
 use tracing::trace;
 use url::Url;
 
-use crate::credential::{Credentials, SLOT_DIR};
+use crate::credential::{self, Credentials, SLOT_DIR};
 use crate::{browser, server::LocalServer};
 
+const SESSION_CREATION_PAGE: &str = "https://x.cartridge.gg/slot/session";
 const SESSION_FILE_BASE_NAME: &str = "session.json";
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -40,6 +43,21 @@ pub struct SessionCredentials {
     pub authorization: Vec<FieldElement>,
 }
 
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error(transparent)]
+    IO(#[from] io::Error),
+
+    #[error(transparent)]
+    Auth(#[from] credential::Error),
+
+    #[error(transparent)]
+    Serde(#[from] serde_json::Error),
+
+    #[error(transparent)]
+    Other(#[from] anyhow::Error),
+}
+
 /// Retrieves the session for the given chain id of the currently authenticated user.
 /// Returns `None` if no session can be found for the chain id.
 ///
@@ -47,7 +65,7 @@ pub struct SessionCredentials {
 ///
 /// This function will return an error if there is no authenticated user.
 ///
-pub fn get(chain_id: FieldElement) -> anyhow::Result<Option<SessionDetails>> {
+pub fn get(chain_id: FieldElement) -> Result<Option<SessionDetails>, Error> {
     let credentials = Credentials::load()?;
     let username = credentials.account.expect("id must exist").id;
     let path = get_file_path(&username, chain_id);
@@ -66,7 +84,7 @@ pub fn get(chain_id: FieldElement) -> anyhow::Result<Option<SessionDetails>> {
 ///
 /// This function will return an error if there is no authenticated user.
 ///
-pub fn store(chain_id: FieldElement, session: &SessionDetails) -> anyhow::Result<PathBuf> {
+pub fn store(chain_id: FieldElement, session: &SessionDetails) -> Result<PathBuf, Error> {
     // TODO: maybe can store the authenticated user in a global variable so that
     // we don't have to call load again if we already did it before.
     let credentials = Credentials::load()?;
@@ -94,7 +112,7 @@ pub fn store(chain_id: FieldElement, session: &SessionDetails) -> anyhow::Result
 /// This function will return an error if there is no authenticated user.
 ///
 #[tracing::instrument(level = "trace", skip(rpc_url), fields(policies = policies.len()))]
-pub async fn create<U>(rpc_url: U, policies: &[Policy]) -> anyhow::Result<SessionDetails>
+pub async fn create<U>(rpc_url: U, policies: &[Policy]) -> Result<SessionDetails, Error>
 where
     U: Into<Url>,
 {
@@ -104,7 +122,7 @@ where
     let rpc_url: Url = rpc_url.into();
     let mut rx = open_session_creation_page(&username, rpc_url.as_str(), policies)?;
 
-    rx.recv().await.context("Channel dropped.")
+    Ok(rx.recv().await.context("Channel dropped.")?)
 }
 
 /// Starts the session creation process by opening the browser to the Cartridge keychain to prompt
@@ -115,7 +133,7 @@ fn open_session_creation_page(
     policies: &[Policy],
 ) -> anyhow::Result<Receiver<SessionDetails>> {
     let params = prepare_query_params(username, rpc_url, policies)?;
-    let url = format!("https://x.cartridge.gg/slot/session?{params}");
+    let url = format!("{SESSION_CREATION_PAGE}?{params}");
 
     let (tx, rx) = channel::<SessionDetails>(1);
     let server = callback_server(tx)?;
@@ -154,10 +172,9 @@ fn prepare_query_params(
 
 /// Create the callback server that will receive the session token from the browser.
 fn callback_server(tx: Sender<SessionDetails>) -> anyhow::Result<LocalServer> {
-    let handler = move |State(tx): State<Sender<SessionDetails>>,
-                        Json(session): Json<SessionDetails>| async move {
+    let handler = move |tx: State<Sender<SessionDetails>>, session: Json<SessionDetails>| async move {
         trace!("Received session token from the browser.");
-        tx.send(session).await.expect("qed; channel closed");
+        tx.0.send(session.0).await.expect("qed; channel closed");
     };
 
     let router = Router::new()
@@ -178,7 +195,7 @@ fn get_file_path(username: &str, chain_id: FieldElement) -> PathBuf {
 #[cfg(test)]
 mod tests {
     #[test]
-    fn get_session() {}
+    fn get_session_when_not_authenticated() {}
 
     #[test]
     fn store_session() {}