diff --git a/src/chat.rs b/src/chat.rs
index 2101fc221..f0f3d0e6d 100644
--- a/src/chat.rs
+++ b/src/chat.rs
@@ -1114,7 +1114,7 @@ pub fn create_by_contact_id(context: &Context, contact_id: u32) -> Result<ChatId
     Ok(chat_id)
 }
 
-pub fn update_saved_messages_icon(context: &Context) -> Result<(), Error> {
+pub(crate) fn update_saved_messages_icon(context: &Context) -> Result<(), Error> {
     // if there is no saved-messages chat, there is nothing to update. this is no error.
     if let Ok((chat_id, _)) = lookup_by_contact_id(context, DC_CONTACT_ID_SELF) {
         let icon = include_bytes!("../assets/icon-saved-messages.png");
@@ -1128,7 +1128,7 @@ pub fn update_saved_messages_icon(context: &Context) -> Result<(), Error> {
     Ok(())
 }
 
-pub fn update_device_icon(context: &Context) -> Result<(), Error> {
+pub(crate) fn update_device_icon(context: &Context) -> Result<(), Error> {
     // if there is no device-chat, there is nothing to update. this is no error.
     if let Ok((chat_id, _)) = lookup_by_contact_id(context, DC_CONTACT_ID_DEVICE) {
         let icon = include_bytes!("../assets/icon-device.png");
@@ -1162,13 +1162,13 @@ fn update_special_chat_name(
     Ok(())
 }
 
-pub fn update_special_chat_names(context: &Context) -> Result<(), Error> {
+pub(crate) fn update_special_chat_names(context: &Context) -> Result<(), Error> {
     update_special_chat_name(context, DC_CONTACT_ID_DEVICE, StockMessage::DeviceMessages)?;
     update_special_chat_name(context, DC_CONTACT_ID_SELF, StockMessage::SavedMessages)?;
     Ok(())
 }
 
-pub fn create_or_lookup_by_contact_id(
+pub(crate) fn create_or_lookup_by_contact_id(
     context: &Context,
     contact_id: u32,
     create_blocked: Blocked,
@@ -1219,7 +1219,7 @@ pub fn create_or_lookup_by_contact_id(
     lookup_by_contact_id(context, contact_id)
 }
 
-pub fn lookup_by_contact_id(
+pub(crate) fn lookup_by_contact_id(
     context: &Context,
     contact_id: u32,
 ) -> Result<(ChatId, Blocked), Error> {
@@ -1273,7 +1273,7 @@ pub fn prepare_msg<'a>(
     Ok(msg_id)
 }
 
-pub fn msgtype_has_file(msgtype: Viewtype) -> bool {
+pub(crate) fn msgtype_has_file(msgtype: Viewtype) -> bool {
     match msgtype {
         Viewtype::Unknown => false,
         Viewtype::Text => false,
@@ -1750,7 +1750,11 @@ pub fn create_group_chat(
     Ok(chat_id)
 }
 
-pub fn add_to_chat_contacts_table(context: &Context, chat_id: ChatId, contact_id: u32) -> bool {
+pub(crate) fn add_to_chat_contacts_table(
+    context: &Context,
+    chat_id: ChatId,
+    contact_id: u32,
+) -> bool {
     // add a contact to a chat; the function does not check the type or if any of the record exist or are already
     // added to the chat!
     sql::execute(
@@ -1762,7 +1766,7 @@ pub fn add_to_chat_contacts_table(context: &Context, chat_id: ChatId, contact_id
     .is_ok()
 }
 
-pub fn remove_from_chat_contacts_table(
+pub(crate) fn remove_from_chat_contacts_table(
     context: &Context,
     chat_id: ChatId,
     contact_id: u32,
@@ -1898,7 +1902,7 @@ fn real_group_exists(context: &Context, chat_id: ChatId) -> bool {
         .unwrap_or_default()
 }
 
-pub fn reset_gossiped_timestamp(context: &Context, chat_id: ChatId) -> Result<(), Error> {
+pub(crate) fn reset_gossiped_timestamp(context: &Context, chat_id: ChatId) -> Result<(), Error> {
     set_gossiped_timestamp(context, chat_id, 0)
 }
 
@@ -1915,7 +1919,7 @@ pub fn get_gossiped_timestamp(context: &Context, chat_id: ChatId) -> i64 {
         .unwrap_or_default()
 }
 
-pub fn set_gossiped_timestamp(
+pub(crate) fn set_gossiped_timestamp(
     context: &Context,
     chat_id: ChatId,
     timestamp: i64,
@@ -1935,7 +1939,7 @@ pub fn set_gossiped_timestamp(
     Ok(())
 }
 
-pub fn shall_attach_selfavatar(context: &Context, chat_id: ChatId) -> Result<bool, Error> {
+pub(crate) fn shall_attach_selfavatar(context: &Context, chat_id: ChatId) -> Result<bool, Error> {
     // versions before 12/2019 already allowed to set selfavatar, however, it was never sent to others.
     // to avoid sending out previously set selfavatars unexpectedly we added this additional check.
     // it can be removed after some time.
@@ -2117,7 +2121,10 @@ fn set_group_explicitly_left(context: &Context, grpid: impl AsRef<str>) -> Resul
     Ok(())
 }
 
-pub fn is_group_explicitly_left(context: &Context, grpid: impl AsRef<str>) -> Result<bool, Error> {
+pub(crate) fn is_group_explicitly_left(
+    context: &Context,
+    grpid: impl AsRef<str>,
+) -> Result<bool, Error> {
     context
         .sql
         .exists(
@@ -2339,7 +2346,7 @@ pub fn forward_msgs(context: &Context, msg_ids: &[MsgId], chat_id: ChatId) -> Re
     Ok(())
 }
 
-pub fn get_chat_contact_cnt(context: &Context, chat_id: ChatId) -> usize {
+pub(crate) fn get_chat_contact_cnt(context: &Context, chat_id: ChatId) -> usize {
     context
         .sql
         .query_get_value::<_, isize>(
@@ -2350,7 +2357,7 @@ pub fn get_chat_contact_cnt(context: &Context, chat_id: ChatId) -> usize {
         .unwrap_or_default() as usize
 }
 
-pub fn get_chat_cnt(context: &Context) -> usize {
+pub(crate) fn get_chat_cnt(context: &Context) -> usize {
     if context.sql.is_open() {
         /* no database, no chats - this is no error (needed eg. for information) */
         context
@@ -2465,7 +2472,7 @@ pub fn was_device_msg_ever_added(context: &Context, label: &str) -> Result<bool,
 //   no wrong information are shown in the device chat
 // - deletion in `devmsglabels` makes sure,
 //   deleted messages are resetted and useful messages can be added again
-pub fn delete_and_reset_all_device_msgs(context: &Context) -> Result<(), Error> {
+pub(crate) fn delete_and_reset_all_device_msgs(context: &Context) -> Result<(), Error> {
     context.sql.execute(
         "DELETE FROM msgs WHERE from_id=?;",
         params![DC_CONTACT_ID_DEVICE],
@@ -2479,7 +2486,7 @@ pub fn delete_and_reset_all_device_msgs(context: &Context) -> Result<(), Error>
 /// Adds an informational message to chat.
 ///
 /// For example, it can be a message showing that a member was added to a group.
-pub fn add_info_msg(context: &Context, chat_id: ChatId, text: impl AsRef<str>) {
+pub(crate) fn add_info_msg(context: &Context, chat_id: ChatId, text: impl AsRef<str>) {
     let rfc724_mid = dc_create_outgoing_rfc724_mid(None, "@device");
 
     if context.sql.execute(
diff --git a/src/contact.rs b/src/contact.rs
index 63197ab79..a2f493f9c 100644
--- a/src/contact.rs
+++ b/src/contact.rs
@@ -146,7 +146,7 @@ impl Origin {
 }
 
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub enum Modifier {
+pub(crate) enum Modifier {
     None,
     Modified,
     Created,
@@ -324,7 +324,7 @@ impl Contact {
     /// Depending on the origin, both, "row_name" and "row_authname" are updated from "name".
     ///
     /// Returns the contact_id and a `Modifier` value indicating if a modification occured.
-    pub fn add_or_lookup(
+    pub(crate) fn add_or_lookup(
         context: &Context,
         name: impl AsRef<str>,
         addr: impl AsRef<str>,
@@ -1019,7 +1019,7 @@ fn set_block_contact(context: &Context, contact_id: u32, new_blocking: bool) {
     }
 }
 
-pub fn set_profile_image(
+pub(crate) fn set_profile_image(
     context: &Context,
     contact_id: u32,
     profile_image: &AvatarAction,
diff --git a/src/context.rs b/src/context.rs
index c7ae9b63d..a037e7a7f 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -51,7 +51,7 @@ pub struct Context {
     cb: Box<ContextCallback>,
     pub os_name: Option<String>,
     pub cmdline_sel_chat_id: Arc<RwLock<ChatId>>,
-    pub bob: Arc<RwLock<BobStatus>>,
+    pub(crate) bob: Arc<RwLock<BobStatus>>,
     pub last_smeared_timestamp: RwLock<i64>,
     pub running_state: Arc<RwLock<RunningState>>,
     /// Mutex to avoid generating the key for the user more than once.
@@ -478,14 +478,14 @@ impl Default for RunningState {
 }
 
 #[derive(Debug, Default)]
-pub struct BobStatus {
+pub(crate) struct BobStatus {
     pub expects: i32,
     pub status: i32,
     pub qr_scan: Option<Lot>,
 }
 
 #[derive(Debug, PartialEq)]
-pub enum PerformJobsNeeded {
+pub(crate) enum PerformJobsNeeded {
     Not,
     AtOnce,
     AvoidDos,
@@ -502,7 +502,7 @@ pub struct SmtpState {
     pub idle: bool,
     pub suspended: bool,
     pub doing_jobs: bool,
-    pub perform_jobs_needed: PerformJobsNeeded,
+    pub(crate) perform_jobs_needed: PerformJobsNeeded,
     pub probe_network: bool,
 }
 
diff --git a/src/lib.rs b/src/lib.rs
index dff1c8fcb..3bd459ad9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -27,7 +27,7 @@ pub(crate) mod events;
 pub use events::*;
 
 mod aheader;
-pub mod blob;
+mod blob;
 pub mod chat;
 pub mod chatlist;
 pub mod config;
@@ -42,7 +42,7 @@ pub mod imex;
 pub mod job;
 mod job_thread;
 pub mod key;
-pub mod keyring;
+mod keyring;
 pub mod location;
 mod login_param;
 pub mod lot;
diff --git a/src/location.rs b/src/location.rs
index 6bde075c4..4f8072278 100644
--- a/src/location.rs
+++ b/src/location.rs
@@ -364,6 +364,7 @@ fn is_marker(txt: &str) -> bool {
     txt.len() == 1 && !txt.starts_with(' ')
 }
 
+/// Deletes all locations from the database.
 pub fn delete_all(context: &Context) -> Result<(), Error> {
     sql::execute(context, &context.sql, "DELETE FROM locations;", params![])?;
     context.call_cb(Event::LocationChanged(None));
@@ -547,7 +548,7 @@ pub fn save(
 }
 
 #[allow(non_snake_case)]
-pub fn JobMaybeSendLocations(context: &Context, _job: &Job) -> job::Status {
+pub(crate) fn JobMaybeSendLocations(context: &Context, _job: &Job) -> job::Status {
     let now = time();
     let mut continue_streaming = false;
     info!(
@@ -638,7 +639,7 @@ pub fn JobMaybeSendLocations(context: &Context, _job: &Job) -> job::Status {
 }
 
 #[allow(non_snake_case)]
-pub fn JobMaybeSendLocationsEnded(context: &Context, job: &mut Job) -> job::Status {
+pub(crate) fn JobMaybeSendLocationsEnded(context: &Context, job: &mut Job) -> job::Status {
     // this function is called when location-streaming _might_ have ended for a chat.
     // the function checks, if location-streaming is really ended;
     // if so, a device-message is added if not yet done.
diff --git a/src/message.rs b/src/message.rs
index 7ad619570..aba9b094c 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -161,7 +161,7 @@ pub struct InvalidMsgId;
     Deserialize,
 )]
 #[repr(u8)]
-pub enum MessengerMessage {
+pub(crate) enum MessengerMessage {
     No = 0,
     Yes = 1,
 
diff --git a/src/mimeparser.rs b/src/mimeparser.rs
index 817360879..0a4e1bac7 100644
--- a/src/mimeparser.rs
+++ b/src/mimeparser.rs
@@ -46,26 +46,17 @@ pub struct MimeMessage {
     pub is_system_message: SystemMessage,
     pub location_kml: Option<location::Kml>,
     pub message_kml: Option<location::Kml>,
-    pub user_avatar: Option<AvatarAction>,
-    pub group_avatar: Option<AvatarAction>,
+    pub(crate) user_avatar: Option<AvatarAction>,
+    pub(crate) group_avatar: Option<AvatarAction>,
     pub(crate) reports: Vec<Report>,
 }
 
 #[derive(Debug, PartialEq)]
-pub enum AvatarAction {
+pub(crate) enum AvatarAction {
     Delete,
     Change(String),
 }
 
-impl AvatarAction {
-    pub fn is_change(&self) -> bool {
-        match self {
-            AvatarAction::Delete => false,
-            AvatarAction::Change(_) => true,
-        }
-    }
-}
-
 #[derive(Debug, Display, Clone, Copy, PartialEq, Eq, FromPrimitive, ToPrimitive, ToSql, FromSql)]
 #[repr(i32)]
 pub enum SystemMessage {
@@ -1094,6 +1085,15 @@ mod tests {
     use super::*;
     use crate::test_utils::*;
 
+    impl AvatarAction {
+        pub fn is_change(&self) -> bool {
+            match self {
+                AvatarAction::Delete => false,
+                AvatarAction::Change(_) => true,
+            }
+        }
+    }
+
     #[test]
     fn test_dc_mimeparser_crash() {
         let context = dummy_context();
diff --git a/src/provider/mod.rs b/src/provider/mod.rs
index a52a41905..7f7174774 100644
--- a/src/provider/mod.rs
+++ b/src/provider/mod.rs
@@ -1,3 +1,5 @@
+//! [Provider database](https://providers.delta.chat/) module
+
 mod data;
 
 use crate::dc_tools::EmailAddress;