diff --git a/diode-file-bindings/src/lib.rs b/diode-file-bindings/src/lib.rs
index d7e01ee..8623e42 100644
--- a/diode-file-bindings/src/lib.rs
+++ b/diode-file-bindings/src/lib.rs
@@ -9,6 +9,9 @@ use std::{
     str::FromStr,
 };
 
+/// # Panics
+///
+/// Will return `Err` if ip and port cannot be parsed.
 #[unsafe(no_mangle)]
 #[allow(clippy::missing_safety_doc)]
 pub unsafe extern "C" fn diode_new_config(
@@ -41,6 +44,9 @@ pub unsafe extern "C" fn diode_free_config(ptr: *mut file::Config<aux::DiodeSend
     }
 }
 
+/// # Panics
+///
+/// Will return `Err` if reference to `config` is wrong.
 #[unsafe(no_mangle)]
 #[allow(clippy::missing_safety_doc)]
 pub unsafe extern "C" fn diode_send_file(
@@ -58,9 +64,13 @@ pub unsafe extern "C" fn diode_send_file(
     let cstr_filepath = unsafe { CStr::from_ptr(ptr_filepath) };
     let rust_filepath = String::from_utf8_lossy(cstr_filepath.to_bytes()).to_string();
 
-    file::send::send_file(config, &rust_filepath).unwrap_or(0) as u32
+    let result: usize = file::send::send_file(config, &rust_filepath).unwrap_or(0);
+    u32::try_from(result).unwrap_or(0)
 }
 
+/// # Panics
+///
+/// Will return `Err` if reference to `config` is wrong.
 #[unsafe(no_mangle)]
 #[allow(clippy::missing_safety_doc)]
 pub unsafe extern "C" fn diode_receive_files(
diff --git a/src/aux/file/receive.rs b/src/aux/file/receive.rs
index cd07d0a..84c163e 100644
--- a/src/aux/file/receive.rs
+++ b/src/aux/file/receive.rs
@@ -10,6 +10,9 @@ use std::{
     path, thread,
 };
 
+/// # Errors
+///
+/// Will return `Err` if `output_dir` is not a directory.
 pub fn receive_files(
     config: &file::Config<aux::DiodeReceive>,
     output_dir: &path::Path,
diff --git a/src/aux/file/send.rs b/src/aux/file/send.rs
index 6f64b52..bc7bcbc 100644
--- a/src/aux/file/send.rs
+++ b/src/aux/file/send.rs
@@ -10,6 +10,10 @@ use std::{
     path,
 };
 
+/// # Errors
+///
+/// Will return `Err` if `send_file` function
+/// returns an `Err`.
 pub fn send_files(
     config: &file::Config<aux::DiodeSend>,
     files: &[String],
@@ -21,6 +25,13 @@ pub fn send_files(
     Ok(())
 }
 
+/// # Errors
+///
+/// Will return `Err` if:
+/// - `net::TcpStream::connect(socket_addr)?`
+///   or
+/// - `unix::net::UnixStream::connect(path)?`
+///   fails.
 pub fn send_file(
     config: &file::Config<aux::DiodeSend>,
     file_path: &String,
diff --git a/src/aux/udp/receive.rs b/src/aux/udp/receive.rs
index 017aa38..c3c2e7f 100644
--- a/src/aux/udp/receive.rs
+++ b/src/aux/udp/receive.rs
@@ -73,6 +73,10 @@ fn receive_tcp_loop(
     }
 }
 
+/// # Errors
+///
+/// Will return `Err` if `from_unix` `PathBuf`
+/// already exists.
 pub fn receive(
     config: &udp::Config<aux::DiodeReceive>,
     to_udp_bind: net::SocketAddr,
diff --git a/src/aux/udp/send.rs b/src/aux/udp/send.rs
index 2da9c5f..475b565 100644
--- a/src/aux/udp/send.rs
+++ b/src/aux/udp/send.rs
@@ -30,6 +30,13 @@ where
     }
 }
 
+/// # Errors
+///
+/// Will return `Err` if:
+/// - `net::TcpStream::connect(socket_addr)?`
+///   or
+/// - `unix::net::UnixStream::connect(path)?`
+///   fails.
 pub fn send(
     config: &udp::Config<aux::DiodeSend>,
     from_udp: net::SocketAddr,
diff --git a/src/lib.rs b/src/lib.rs
index d699278..cccccf5 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -12,6 +12,10 @@ mod sock_utils;
 #[allow(unsafe_code)]
 mod udp;
 
+/// # Errors
+///
+/// Will return `Err` if `file` cannot be opened
+/// or logger cannot be set (Term or file mode).
 pub fn init_logger(
     level_filter: log::LevelFilter,
     file: Option<path::PathBuf>,
diff --git a/src/protocol.rs b/src/protocol.rs
index e67083d..cdd472e 100644
--- a/src/protocol.rs
+++ b/src/protocol.rs
@@ -77,6 +77,11 @@ pub struct RaptorQ {
 }
 
 impl RaptorQ {
+    /// # Errors
+    ///
+    /// Will return `Err` if `symbol_count`
+    ///   or
+    /// `nb_repair_packets` parsing fails
     pub fn new(mtu: u16, block_size: u32, repair_percentage: u32) -> Result<Self, Error> {
         let mut max_packet_size = mtu - PACKET_HEADER_SIZE - RAPTORQ_HEADER_SIZE;
         max_packet_size -= max_packet_size % RAPTORQ_ALIGNMENT;
@@ -110,18 +115,22 @@ impl RaptorQ {
         })
     }
 
+    #[must_use]
     pub const fn block_size(&self) -> u32 {
         self.transfer_length
     }
 
+    #[must_use]
     pub const fn min_nb_packets(&self) -> u16 {
         self.symbol_count
     }
 
+    #[must_use]
     pub fn nb_packets(&self) -> u32 {
         u32::from(self.symbol_count) + u32::from(self.nb_repair_packets)
     }
 
+    #[must_use]
     pub fn encode(&self, block_id: u8, data: &[u8]) -> Vec<raptorq::EncodingPacket> {
         let encoder = raptorq::SourceBlockEncoder::with_encoding_plan(
             block_id,
@@ -139,6 +148,7 @@ impl RaptorQ {
         packets
     }
 
+    #[must_use]
     pub fn decode(&self, block_id: u8, packets: Vec<raptorq::EncodingPacket>) -> Option<Vec<u8>> {
         let mut decoder = raptorq::SourceBlockDecoder::new(
             block_id,
diff --git a/src/receive/mod.rs b/src/receive/mod.rs
index 2dc8be7..f60c52c 100644
--- a/src/receive/mod.rs
+++ b/src/receive/mod.rs
@@ -172,6 +172,10 @@ where
     ClientEnd: Send + Sync + Fn(C, bool),
     E: Into<Error>,
 {
+    /// # Errors
+    ///
+    /// Will return `Err` if `multiplex_control` semaphore
+    /// cannot be created.
     pub fn new(
         config: Config,
         raptorq: protocol::RaptorQ,
@@ -203,6 +207,9 @@ where
         })
     }
 
+    /// # Errors
+    ///
+    /// Will return `Err` if scoped threads cannot spawned.
     #[allow(clippy::too_many_lines)]
     pub fn start<'a>(&'a self, scope: &'a thread::Scope<'a, '_>) -> Result<(), Error> {
         log::info!(
diff --git a/src/send/mod.rs b/src/send/mod.rs
index 07be5e7..74d3f98 100644
--- a/src/send/mod.rs
+++ b/src/send/mod.rs
@@ -123,6 +123,10 @@ impl<C> Sender<C>
 where
     C: Read + AsRawFd + Send,
 {
+    /// # Errors
+    ///
+    /// Will return `Err` if `multiplex_control` semaphore
+    /// cannot be created.
     pub fn new(config: Config, raptorq: protocol::RaptorQ) -> Result<Self, Error> {
         let multiplex_control = semka::Sem::new(config.max_clients)
             .ok_or(Error::Other("failed to create semaphore".into()))?;
@@ -151,6 +155,9 @@ where
         })
     }
 
+    /// # Errors
+    ///
+    /// Will return `Err` if scoped threads cannot spawned.
     pub fn start<'a>(&'a self, scope: &'a thread::Scope<'a, '_>) -> Result<(), Error> {
         log::info!(
             "max {} simultaneous clients/transfers",
@@ -246,14 +253,18 @@ where
 
         Ok(())
     }
-
+    /// # Errors
+    ///
+    /// Will return `Err` if the `send` returns a `SendError<T>`.
     pub fn new_client(&self, client: C) -> Result<(), Error> {
         if let Err(e) = self.to_server.send(Some(client)) {
             return Err(Error::Diode(format!("failed to enqueue client: {e}")));
         }
         Ok(())
     }
-
+    /// # Errors
+    ///
+    /// Will return `Err` if the `send` returns a `SendError<T>`.
     pub fn stop(&self) -> Result<(), Error> {
         if let Err(e) = self.to_server.send(None) {
             return Err(Error::Diode(format!("failed to stop: {e}")));