diff --git a/Cargo.lock b/Cargo.lock
index 3e8c51e..01e1e95 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -39,8 +39,8 @@ dependencies = [
  "encoding_rs",
  "flate2",
  "futures-core",
- "h2",
- "http",
+ "h2 0.3.25",
+ "http 0.2.12",
  "httparse",
  "httpdate",
  "itoa",
@@ -75,7 +75,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d22475596539443685426b6bdadb926ad0ecaefdfc5fb05e5e3441f15463c511"
 dependencies = [
  "bytestring",
- "http",
+ "http 0.2.12",
  "regex",
  "serde",
  "tracing",
@@ -916,7 +916,26 @@ dependencies = [
  "futures-core",
  "futures-sink",
  "futures-util",
- "http",
+ "http 0.2.12",
+ "indexmap",
+ "slab",
+ "tokio",
+ "tokio-util",
+ "tracing",
+]
+
+[[package]]
+name = "h2"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51ee2dd2e4f378392eeff5d51618cd9a63166a2513846bbc55f21cfacd9199d4"
+dependencies = [
+ "bytes",
+ "fnv",
+ "futures-core",
+ "futures-sink",
+ "futures-util",
+ "http 1.1.0",
  "indexmap",
  "slab",
  "tokio",
@@ -952,6 +971,12 @@ dependencies = [
  "unicode-segmentation",
 ]
 
+[[package]]
+name = "hermit-abi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
+
 [[package]]
 name = "hex"
 version = "0.4.3"
@@ -996,6 +1021,40 @@ dependencies = [
  "itoa",
 ]
 
+[[package]]
+name = "http"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "21b9ddb458710bc376481b842f5da65cdf31522de232c1ca8146abce2a358258"
+dependencies = [
+ "bytes",
+ "fnv",
+ "itoa",
+]
+
+[[package]]
+name = "http-body"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1cac85db508abc24a2e48553ba12a996e87244a0395ce011e62b37158745d643"
+dependencies = [
+ "bytes",
+ "http 1.1.0",
+]
+
+[[package]]
+name = "http-body-util"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0475f8b2ac86659c21b64320d5d653f9efe42acd2a4e560073ec61a155a34f1d"
+dependencies = [
+ "bytes",
+ "futures-core",
+ "http 1.1.0",
+ "http-body",
+ "pin-project-lite",
+]
+
 [[package]]
 name = "httparse"
 version = "1.8.0"
@@ -1014,6 +1073,62 @@ version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a3a5bfb195931eeb336b2a7b4d761daec841b97f947d34394601737a7bba5e4"
 
+[[package]]
+name = "hyper"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "186548d73ac615b32a73aafe38fb4f56c0d340e110e5a200bcadbaf2e199263a"
+dependencies = [
+ "bytes",
+ "futures-channel",
+ "futures-util",
+ "h2 0.4.3",
+ "http 1.1.0",
+ "http-body",
+ "httparse",
+ "itoa",
+ "pin-project-lite",
+ "smallvec",
+ "tokio",
+ "want",
+]
+
+[[package]]
+name = "hyper-tls"
+version = "0.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70206fc6890eaca9fde8a0bf71caa2ddfc9fe045ac9e5c70df101a7dbde866e0"
+dependencies = [
+ "bytes",
+ "http-body-util",
+ "hyper",
+ "hyper-util",
+ "native-tls",
+ "tokio",
+ "tokio-native-tls",
+ "tower-service",
+]
+
+[[package]]
+name = "hyper-util"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ca38ef113da30126bbff9cd1705f9273e15d45498615d138b0c20279ac7a76aa"
+dependencies = [
+ "bytes",
+ "futures-channel",
+ "futures-util",
+ "http 1.1.0",
+ "http-body",
+ "hyper",
+ "pin-project-lite",
+ "socket2",
+ "tokio",
+ "tower",
+ "tower-service",
+ "tracing",
+]
+
 [[package]]
 name = "iana-time-zone"
 version = "0.1.60"
@@ -1040,6 +1155,13 @@ dependencies = [
 [[package]]
 name = "icrc-client"
 version = "0.1.0"
+dependencies = [
+ "reqwest",
+ "serde",
+ "thiserror",
+ "tokio",
+ "uuid",
+]
 
 [[package]]
 name = "icrc-server"
@@ -1059,6 +1181,7 @@ dependencies = [
  "rand",
  "serde",
  "sqlx",
+ "strum",
  "thiserror",
  "tokio",
  "uuid",
@@ -1084,6 +1207,12 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "ipnet"
+version = "2.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f518f335dce6725a761382244631d86cf0ccb2863413590b31338feb467f9c3"
+
 [[package]]
 name = "itertools"
 version = "0.12.1"
@@ -1324,6 +1453,16 @@ dependencies = [
  "libm",
 ]
 
+[[package]]
+name = "num_cpus"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4161fcb6d602d4d2081af7c3a45852d875a03dd337a6bfdd6e06407b61342a43"
+dependencies = [
+ "hermit-abi",
+ "libc",
+]
+
 [[package]]
 name = "object"
 version = "0.32.2"
@@ -1438,6 +1577,26 @@ version = "2.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e3148f5046208a5d56bcfc03053e3ca6334e51da8dfb19b6cdc8b306fae3283e"
 
+[[package]]
+name = "pin-project"
+version = "1.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6bf43b791c5b9e34c3d182969b4abb522f9343702850a2e57f460d00d09b4b3"
+dependencies = [
+ "pin-project-internal",
+]
+
+[[package]]
+name = "pin-project-internal"
+version = "1.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2f38a4412a78282e09a2cf38d195ea5420d15ba0602cb375210efbc877243965"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.57",
+]
+
 [[package]]
 name = "pin-project-lite"
 version = "0.2.14"
@@ -1575,6 +1734,48 @@ version = "0.8.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "adad44e29e4c806119491a7f06f03de4d1af22c3a680dd47f1e6e179439d1f56"
 
+[[package]]
+name = "reqwest"
+version = "0.12.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d66674f2b6fb864665eea7a3c1ac4e3dfacd2fda83cf6f935a612e01b0e3338"
+dependencies = [
+ "base64 0.21.7",
+ "bytes",
+ "encoding_rs",
+ "futures-core",
+ "futures-util",
+ "h2 0.4.3",
+ "http 1.1.0",
+ "http-body",
+ "http-body-util",
+ "hyper",
+ "hyper-tls",
+ "hyper-util",
+ "ipnet",
+ "js-sys",
+ "log",
+ "mime",
+ "native-tls",
+ "once_cell",
+ "percent-encoding",
+ "pin-project-lite",
+ "rustls-pemfile",
+ "serde",
+ "serde_json",
+ "serde_urlencoded",
+ "sync_wrapper",
+ "system-configuration",
+ "tokio",
+ "tokio-native-tls",
+ "tower-service",
+ "url",
+ "wasm-bindgen",
+ "wasm-bindgen-futures",
+ "web-sys",
+ "winreg",
+]
+
 [[package]]
 name = "rsa"
 version = "0.9.6"
@@ -1623,6 +1824,21 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "rustls-pemfile"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1c74cae0a4cf6ccbbf5f359f08efdf8ee7e1dc532573bf0db71968cb56b1448c"
+dependencies = [
+ "base64 0.21.7",
+]
+
+[[package]]
+name = "rustversion"
+version = "1.0.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ffc183a10b4478d04cbbbfc96d0873219d962dd5accaff2ffbd4ceb7df837f4"
+
 [[package]]
 name = "ryu"
 version = "1.0.17"
@@ -2028,6 +2244,28 @@ dependencies = [
  "unicode-normalization",
 ]
 
+[[package]]
+name = "strum"
+version = "0.26.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d8cec3501a5194c432b2b7976db6b7d10ec95c253208b45f83f7136aa985e29"
+dependencies = [
+ "strum_macros",
+]
+
+[[package]]
+name = "strum_macros"
+version = "0.26.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c6cf59daf282c0a494ba14fd21610a0325f9f90ec9d1231dea26bcb1d696c946"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "rustversion",
+ "syn 2.0.57",
+]
+
 [[package]]
 name = "subtle"
 version = "2.5.0"
@@ -2056,6 +2294,33 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "sync_wrapper"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2047c6ded9c721764247e62cd3b03c09ffc529b2ba5b10ec482ae507a4a70160"
+
+[[package]]
+name = "system-configuration"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba3a3adc5c275d719af8cb4272ea1c4a6d668a777f37e115f6d11ddbc1c8e0e7"
+dependencies = [
+ "bitflags 1.3.2",
+ "core-foundation",
+ "system-configuration-sys",
+]
+
+[[package]]
+name = "system-configuration-sys"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a75fb188eb626b924683e3b95e3a48e63551fcfb51949de2f06a9d91dbee93c9"
+dependencies = [
+ "core-foundation-sys",
+ "libc",
+]
+
 [[package]]
 name = "tempfile"
 version = "3.10.1"
@@ -2144,13 +2409,36 @@ dependencies = [
  "bytes",
  "libc",
  "mio",
+ "num_cpus",
  "parking_lot",
  "pin-project-lite",
  "signal-hook-registry",
  "socket2",
+ "tokio-macros",
  "windows-sys 0.48.0",
 ]
 
+[[package]]
+name = "tokio-macros"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b8a1e28f2deaa14e508979454cb3a223b10b938b45af148bc0986de36f1923b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.57",
+]
+
+[[package]]
+name = "tokio-native-tls"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbae76ab933c85776efabc971569dd6119c580d8f5d448769dec1764bf796ef2"
+dependencies = [
+ "native-tls",
+ "tokio",
+]
+
 [[package]]
 name = "tokio-stream"
 version = "0.1.15"
@@ -2176,6 +2464,34 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "tower"
+version = "0.4.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b8fa9be0de6cf49e536ce1851f987bd21a43b771b09473c3549a6c853db37c1c"
+dependencies = [
+ "futures-core",
+ "futures-util",
+ "pin-project",
+ "pin-project-lite",
+ "tokio",
+ "tower-layer",
+ "tower-service",
+ "tracing",
+]
+
+[[package]]
+name = "tower-layer"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c20c8dbed6283a09604c3e69b4b7eeb54e298b8a600d4d5ecb5ad39de609f1d0"
+
+[[package]]
+name = "tower-service"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6bc1c9ce2b5135ac7f93c72918fc37feb872bdc6a5533a8b85eb4b86bfdae52"
+
 [[package]]
 name = "tracing"
 version = "0.1.40"
@@ -2208,6 +2524,12 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "try-lock"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e421abadd41a4225275504ea4d6566923418b7f05506fbc9c0fe86ba7396114b"
+
 [[package]]
 name = "typenum"
 version = "1.17.0"
@@ -2291,6 +2613,15 @@ version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
+[[package]]
+name = "want"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bfa7760aed19e106de2c7c0b581b509f2f25d3dacaf737cb82ac61bc6d760b0e"
+dependencies = [
+ "try-lock",
+]
+
 [[package]]
 name = "wasi"
 version = "0.11.0+wasi-snapshot-preview1"
@@ -2328,6 +2659,18 @@ dependencies = [
  "wasm-bindgen-shared",
 ]
 
+[[package]]
+name = "wasm-bindgen-futures"
+version = "0.4.42"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "76bc14366121efc8dbb487ab05bcc9d346b3b5ec0eaa76e46594cabbe51762c0"
+dependencies = [
+ "cfg-if",
+ "js-sys",
+ "wasm-bindgen",
+ "web-sys",
+]
+
 [[package]]
 name = "wasm-bindgen-macro"
 version = "0.2.92"
@@ -2357,6 +2700,16 @@ version = "0.2.92"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "af190c94f2773fdb3729c55b007a722abb5384da03bc0986df4c289bf5567e96"
 
+[[package]]
+name = "web-sys"
+version = "0.3.69"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77afa9a11836342370f4817622a2f0f418b134426d91a82dfb48f532d2ec13ef"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "whoami"
 version = "1.5.1"
@@ -2508,6 +2861,16 @@ version = "0.52.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32b752e52a2da0ddfbdbcc6fceadfeede4c939ed16d13e648833a61dfb611ed8"
 
+[[package]]
+name = "winreg"
+version = "0.50.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "524e57b2c537c0f9b1e69f1965311ec12182b4122e45035b1508cd24d2adadb1"
+dependencies = [
+ "cfg-if",
+ "windows-sys 0.48.0",
+]
+
 [[package]]
 name = "zerocopy"
 version = "0.7.32"
diff --git a/client/Cargo.toml b/client/Cargo.toml
index 2ca6feb..c2651b0 100644
--- a/client/Cargo.toml
+++ b/client/Cargo.toml
@@ -4,3 +4,8 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+reqwest = { version = "0.12.2", features = ["json"] }
+serde = { version = "1.0.197", features = ["derive"] }
+thiserror = "1.0.58"
+tokio = { version = "1.37.0", features = ["full"] }
+uuid = "1.8.0"
diff --git a/client/src/error.rs b/client/src/error.rs
new file mode 100644
index 0000000..41a8688
--- /dev/null
+++ b/client/src/error.rs
@@ -0,0 +1,17 @@
+#[derive(Debug, thiserror::Error, Clone)]
+pub enum Error {
+    #[error("Failed to handle a server response: {0}")]
+    BadResponse(String),
+
+    #[error("Failed to communicate with the host")]
+    ConnectionError,
+
+    #[error("Failed to authorize the session with the given token")]
+    InvalidToken,
+
+    #[error("The token used to authenticate the session is expired")]
+    TokenExpired,
+
+    #[error("{0}")]
+    Unknown(String),
+}
diff --git a/client/src/lib.rs b/client/src/lib.rs
index 7d12d9a..3711d10 100644
--- a/client/src/lib.rs
+++ b/client/src/lib.rs
@@ -1,14 +1,21 @@
-pub fn add(left: usize, right: usize) -> usize {
-    left + right
-}
+mod error;
+mod session;
+
+pub use session::Session;
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
+    #[tokio::test]
+    async fn authorized_session() {
+        let host = std::env::var("ICRC_TEST_HOST")
+            .expect("The environment variable ICRC_TEST_HOST needs to be set!");
+        let token = std::env::var("ICRC_TEST_AUTH")
+            .expect("The environment variable ICRC_TEST_AUTH needs to be set!");
+
+        let session = Session::new(&host, Some(token)).await.unwrap();
+
+        // assert_eq!(result, 4);
     }
 }
diff --git a/client/src/session/data.rs b/client/src/session/data.rs
new file mode 100644
index 0000000..5bb4ada
--- /dev/null
+++ b/client/src/session/data.rs
@@ -0,0 +1,52 @@
+use serde::Deserialize;
+
+pub mod api {
+    use super::Deserialize;
+
+    pub mod account {
+        use super::Deserialize;
+
+        pub mod info {
+            use super::Deserialize;
+
+            #[derive(Debug, Deserialize)]
+            pub struct Response {
+                pub userid: String,
+                // TODO: make permissions an enum
+                pub permissions: Vec<String>,
+            }
+        }
+    }
+
+    pub mod error {
+        use super::Deserialize;
+
+        #[derive(Debug, thiserror::Error, Deserialize)]
+        pub enum Error {
+            #[error("Failed to authenticate with the given credentials")]
+            AuthenticationFailure,
+
+            #[error("The given token is invalid")]
+            InvalidToken,
+
+            #[error("Permission denied: {0}")]
+            PermissionDenied(String),
+
+            #[error("The given relay id cannot be mapped to a relay")]
+            RelayNotFound,
+
+            #[error("The given token is expired")]
+            TokenExpired,
+
+            #[error("The given user cannot be found")]
+            UserNotFound,
+        }
+
+        #[derive(Debug, Deserialize)]
+        pub struct Body {
+            pub error: Error,
+            #[serde(skip)]
+            description: String,
+        }
+    }
+}
diff --git a/client/src/session/mod.rs b/client/src/session/mod.rs
new file mode 100644
index 0000000..ca4e73b
--- /dev/null
+++ b/client/src/session/mod.rs
@@ -0,0 +1,90 @@
+pub(self) mod data;
+
+use crate::error::Error;
+use std::str::FromStr;
+use uuid::Uuid;
+
+struct AuthorizedSession {
+    token: String,
+    userid: Uuid,
+}
+
+/// A Session is a connection to an ICRC Server.
+/// It can be either authorized or unauthorized.
+/// An unauthorized session is not linked to any account on the server,
+/// but an authorized session uses Bearer Authentication to get access to resources,
+/// which are not publicly accessible.
+pub struct Session {
+    host: String,
+    client: reqwest::Client,
+
+    auth: Option<AuthorizedSession>,
+}
+
+impl Session {
+    /// Creates a new [Session] with `host` as the ICRC Server host.
+    /// Giving `auth` the value [None] sets the session in an unauthorized state,
+    /// whilst [Some]`(token)` calls [Session::auth_with_token].
+    pub async fn new(mut host: &str, auth: Option<String>) -> Result<Self, Error> {
+        if let Some(stripped) = host.strip_suffix("/") {
+            host = stripped;
+        }
+
+        let mut session = Self {
+            host: host.to_string(),
+            client: reqwest::Client::new(),
+            auth: None,
+        };
+        if let Some(token) = auth {
+            session.auth_with_token(token).await?;
+        }
+
+        Ok(session)
+    }
+
+    /// Tries to authorize the session. If `token` is not accepted by the server, this leads to an
+    /// [crate::error::Error::InvalidToken] or [crate::error::Error::TokenExpired] error.
+    pub async fn auth_with_token(&mut self, token: String) -> Result<(), Error> {
+        let request = self
+            .client
+            .get(format!("{host}/account/info", host = self.host))
+            .bearer_auth(&token);
+
+        let response = match request.send().await {
+            Ok(resp) => {
+                if resp.status().is_success() {
+                    resp.json::<data::api::account::info::Response>()
+                        .await
+                        .map_err(|e| Error::BadResponse(e.to_string()))?
+                } else {
+                    return Err(
+                        match resp
+                            .json::<data::api::error::Body>()
+                            .await
+                            .map_err(|e| Error::BadResponse(e.to_string()))?
+                            .error
+                        {
+                            data::api::error::Error::InvalidToken => Error::InvalidToken,
+                            data::api::error::Error::TokenExpired => Error::TokenExpired,
+                            e => Error::BadResponse(format!("Unknown Error/{e} in this context")),
+                        },
+                    );
+                }
+            }
+            Err(e) => {
+                if e.is_connect() || e.is_timeout() {
+                    return Err(Error::ConnectionError);
+                }
+                return Err(Error::Unknown(e.to_string()));
+            }
+        };
+
+        self.auth = Some(AuthorizedSession {
+            token,
+            userid: Uuid::from_str(&response.userid)
+                .map_err(|_| Error::BadResponse("Failed to parse userid".to_string()))?,
+        });
+
+        Ok(())
+    }
+}