diff --git a/modules/global-db/dap_chain_global_db.c b/modules/global-db/dap_chain_global_db.c
index 65983fbe02ff6c3a704baf60c10d32e1ef6589b6..89d1fbd18ad9ab89166f48dffea62acc494ab387 100644
--- a/modules/global-db/dap_chain_global_db.c
+++ b/modules/global-db/dap_chain_global_db.c
@@ -351,7 +351,6 @@ static bool global_db_gr_del_add(char *a_key,const char *a_group, time_t a_times
     return false;
 }
 
-
 /**
  * @brief Deletes info about the deleted object from the database
  * @param a_key an object key string, looked like "0x8FAFBD00B..."
@@ -379,7 +378,6 @@ static bool global_db_gr_del_del(char *a_key, const char *a_group)
     return false;
 }
 
-
 /**
  * @brief Gets time stamp of the deleted object by a_group and a_key arguments.
  * @param a_group a group name sring, for example "kelvin-testnet.nodes"
@@ -420,7 +418,6 @@ bool dap_chain_global_db_del(char *a_key)
     return dap_chain_global_db_gr_del(a_key, GROUP_LOCAL_GENERAL);
 }
 
-
 /**
  * @brief Gets a last item from a database by a_group.
  * @param a_group a group name string
@@ -556,7 +553,6 @@ void dap_global_db_obj_track_history(void* a_store_data)
     }
 }
 
-
 /**
  * @brief Adds a value to a database.
  * @param a_key a object key string
diff --git a/modules/global-db/dap_chain_global_db_driver_cdb.c b/modules/global-db/dap_chain_global_db_driver_cdb.c
index 0a480510b8caf414049f29bee3015def5f58ba16..0b647cc4ff8cc6a21702886bb45d7e0c471987e9 100644
--- a/modules/global-db/dap_chain_global_db_driver_cdb.c
+++ b/modules/global-db/dap_chain_global_db_driver_cdb.c
@@ -141,7 +141,7 @@ bool dap_cdb_get_cond_obj_iter_callback(void *arg, const char *key, int ksize, c
     return true;
 }
 
-//** A callback function designed for countng items*/
+//** A callback function designed for counting items*/
 bool dap_cdb_get_count_iter_callback(void *arg, const char *key, int ksize, const char *val, int vsize, uint32_t expire, uint64_t oid) {
     UNUSED(ksize);
     UNUSED(val);
diff --git a/modules/global-db/dap_chain_global_db_driver_pgsql.c b/modules/global-db/dap_chain_global_db_driver_pgsql.c
index cf692542c7220a3e6d322c8c6c5519edaefcea61..1232f9837bb27b5d8b2b5a7388cf25cfaaa7e98c 100644
--- a/modules/global-db/dap_chain_global_db_driver_pgsql.c
+++ b/modules/global-db/dap_chain_global_db_driver_pgsql.c
@@ -83,9 +83,10 @@ static void s_pgsql_free_connection(PGconn *a_conn)
 }
 
 /**
- * SQLite library initialization, no thread safe
- *
- * return 0 if Ok, else error code >0
+ * @brief Initializes a PostgreSQL database.
+ * @param a_filename_dir a path to the database file
+ * @param a_drv_callback a pointer to a structure of callback functions 
+ * @return If successful returns 0, else a error code <0.
  */
 int dap_db_driver_pgsql_init(const char *a_filename_dir, dap_db_driver_callbacks_t *a_drv_callback)
 {
@@ -189,7 +190,11 @@ int dap_db_driver_pgsql_init(const char *a_filename_dir, dap_db_driver_callbacks
     return 0;
 }
 
-
+/**
+ * @brief Deinitializes a SQLite database.
+ * 
+ * @return Returns 0 if successful.
+ */
 int dap_db_driver_pgsql_deinit(void)
 {
     pthread_rwlock_wrlock(&s_db_rwlock);
@@ -201,7 +206,9 @@ int dap_db_driver_pgsql_deinit(void)
 }
 
 /**
- * Start a transaction
+ * @brief Starts a transaction.
+ * 
+ * @return Returns 0 if successful, otherwise -1.
  */
 int dap_db_driver_pgsql_start_transaction(void)
 {
@@ -220,7 +227,9 @@ int dap_db_driver_pgsql_start_transaction(void)
 }
 
 /**
- * End of transaction
+ * @brief Starts a transaction in a PostgreSQL database.
+ * 
+ * @return Returns 0 if successful, otherwise -1.
  */
 int dap_db_driver_pgsql_end_transaction(void)
 {
@@ -237,9 +246,11 @@ int dap_db_driver_pgsql_end_transaction(void)
 }
 
 /**
- * Create table
- *
- * return 0 if Ok, else error code
+ * @brief Creates a table in a PostgreSQL database.
+ * 
+ * @param a_table_name a table name string
+ * @param a_conn a pointer to the connection object
+ * @return Returns 0 if successful, otherwise -1.
  */
 static int s_pgsql_create_group_table(const char *a_table_name, PGconn *a_conn)
 {
@@ -261,8 +272,10 @@ static int s_pgsql_create_group_table(const char *a_table_name, PGconn *a_conn)
 }
 
 /**
- * Apply data (write or delete)
- *
+ * @brief Applies an object to a PostgreSQL database.
+ * 
+ * @param a_store_obj a pointer to the object structure
+ * @return Returns 0 if successful, else a error code less than zero.
  */
 int dap_db_driver_pgsql_apply_store_obj(dap_store_obj_t *a_store_obj)
 {
@@ -337,6 +350,14 @@ int dap_db_driver_pgsql_apply_store_obj(dap_store_obj_t *a_store_obj)
     return l_ret;
 }
 
+/**
+ * @brief Fills a object from a row
+ * @param a_group a group name string
+ * @param a_obj a pointer to the object
+ * @param a_res a pointer to the result structure
+ * @param a_row a row number
+ * @return (none)
+ */
 static void s_pgsql_fill_object(const char *a_group, dap_store_obj_t *a_obj, PGresult *a_res, int a_row)
 {
     a_obj->group = dap_strdup(a_group);
@@ -356,12 +377,12 @@ static void s_pgsql_fill_object(const char *a_group, dap_store_obj_t *a_obj, PGr
 }
 
 /**
- * Read several items
- *
- * a_group - group name
- * a_key - key name, may by NULL, it means reading the whole group
- * a_count_out[in], how many items to read, 0 - no limits
- * a_count_out[out], how many items was read
+ * @brief Reads some objects from a PostgreSQL database by a_group and a_key.
+ * @param a_group a group name string
+ * @param a_key an object key string, if equals NULL reads the whole group
+ * @param a_count_out[in] a number of objects to be read, if equals 0 reads with no limits
+ * @param a_count_out[out] a number of objects that were read
+ * @return If successful, a pointer to an objects, otherwise a null pointer.
  */
 dap_store_obj_t *dap_db_driver_pgsql_read_store_obj(const char *a_group, const char *a_key, size_t *a_count_out)
 {
@@ -409,9 +430,9 @@ dap_store_obj_t *dap_db_driver_pgsql_read_store_obj(const char *a_group, const c
 }
 
 /**
- * Read last item
- *
- * a_group - group name
+ * @brief Reads a last object from a PostgreSQL database.
+ * @param a_group a group name string
+ * @return Returns a pointer to the object if successful, otherwise a null pointer.
  */
 dap_store_obj_t *dap_db_driver_pgsql_read_last_store_obj(const char *a_group)
 {
@@ -444,12 +465,12 @@ dap_store_obj_t *dap_db_driver_pgsql_read_last_store_obj(const char *a_group)
 }
 
 /**
- * Read several items with conditoin
- *
- * a_group - group name
- * a_id - read from this id
- * a_count_out[in], how many items to read, 0 - no limits
- * a_count_out[out], how many items was read
+ * @brief Reads some objects from a PostgreSQL database by conditions.
+ * @param a_group a group name string
+ * @param a_id id
+ * @param a_count_out[in] a number of objects to be read, if equals 0 reads with no limits
+ * @param a_count_out[out] a number of objects that were read 
+ * @return If successful, a pointer to an objects, otherwise a null pointer. 
  */
 dap_store_obj_t *dap_db_driver_pgsql_read_cond_store_obj(const char *a_group, uint64_t a_id, size_t *a_count_out)
 {
@@ -493,7 +514,11 @@ dap_store_obj_t *dap_db_driver_pgsql_read_cond_store_obj(const char *a_group, ui
     return l_obj;
 }
 
-
+/**
+ * @brief Gets a list of group names from a PostgreSQL database by a_group_mask.
+ * @param a_group_mask a group name mask
+ * @return Returns a pointer to a list of group names if successful, otherwise a null pointer.
+ */
 dap_list_t *dap_db_driver_pgsql_get_groups_by_mask(const char *a_group_mask)
 {
     if (!a_group_mask)
@@ -524,6 +549,12 @@ dap_list_t *dap_db_driver_pgsql_get_groups_by_mask(const char *a_group_mask)
     return l_ret_list;
 }
 
+/**
+ * @brief Reads a number of objects from a PostgreSQL database by a_group and a_id.
+ * @param a_group a group name string
+ * @param a_id id starting from which the quantity is calculated
+ * @return Returns a number of objects.
+ */
 size_t dap_db_driver_pgsql_read_count_store(const char *a_group, uint64_t a_id)
 {
     if (!a_group)
@@ -551,6 +582,12 @@ size_t dap_db_driver_pgsql_read_count_store(const char *a_group, uint64_t a_id)
     return l_ret;
 }
 
+/**
+ * @brief Checks if an object is in a PostgreSQL database by a_group and a_key.
+ * @param a_group a group name string
+ * @param a_key a object key string
+ * @return Returns true if it is, false it's not.
+ */
 bool dap_db_driver_pgsql_is_obj(const char *a_group, const char *a_key)
 {
     if (!a_group)
@@ -577,6 +614,10 @@ bool dap_db_driver_pgsql_is_obj(const char *a_group, const char *a_key)
     return l_ret;
 }
 
+/**
+ * @brief Flushes a PostgreSQ database cahce to disk.
+ * @return Returns 0 if successful, else a error code less than zero.
+ */
 int dap_db_driver_pgsql_flush()
 {
     PGconn *l_conn = s_pgsql_get_connection();
diff --git a/modules/global-db/dap_chain_global_db_hist.c b/modules/global-db/dap_chain_global_db_hist.c
index 9404776f360d6b9d7f5066707b3781ce80b78311..aafef57f07da99f0fb8317dd8e98fe7c285a5cd0 100644
--- a/modules/global-db/dap_chain_global_db_hist.c
+++ b/modules/global-db/dap_chain_global_db_hist.c
@@ -28,6 +28,12 @@ typedef struct dap_tx_data{
 
 #define LOG_TAG "dap_chain_global_db_hist"
 
+/**
+ * @brief Packs members of a_rec structure into a single string.
+ * 
+ * @param a_rec a pointer to the structure
+ * @return Returns the string.
+ */
 static char* dap_db_history_pack_hist(dap_global_db_hist_t *a_rec)
 {
     char *l_ret = dap_strdup_printf("%c%s%u%s%s%s%s", a_rec->type, GLOBAL_DB_HIST_REC_SEPARATOR, a_rec->keys_count,
@@ -35,6 +41,13 @@ static char* dap_db_history_pack_hist(dap_global_db_hist_t *a_rec)
     return l_ret;
 }
 
+/**
+ * @brief Unpacks a single string into a structure.
+ * 
+ * @param l_str_in the string
+ * @param a_rec_out the structure
+ * @return Returns 1 if successful, otherwise -1. 
+ */
 static int dap_db_history_unpack_hist(char *l_str_in, dap_global_db_hist_t *a_rec_out)
 {
     char **l_strv = dap_strsplit(l_str_in, GLOBAL_DB_HIST_REC_SEPARATOR, -1);
@@ -49,6 +62,11 @@ static int dap_db_history_unpack_hist(char *l_str_in, dap_global_db_hist_t *a_re
     return 1;
 }
 
+/**
+ * @brief Gets a current time with a suffix.
+ * 
+ * @return Returns a string containing a current time and a suffix.
+ */
 static char* dap_db_new_history_timestamp()
 {
     static pthread_mutex_t s_mutex = PTHREAD_MUTEX_INITIALIZER;
@@ -75,7 +93,13 @@ static char* dap_db_new_history_timestamp()
 }
 
 /**
- * Add data to the history log
+ * @brief Adds data to the history log.
+ * 
+ * @param a_type a type of record
+ * @param a_store_obj a pointer to the object structure
+ * @param a_dap_store_count a number of objects
+ * @param a_group a group name string
+ * @return Returns true if successful, otherwise false.
  */
 bool dap_db_history_add(char a_type, pdap_store_obj_t a_store_obj, size_t a_dap_store_count, const char *a_group)
 {
@@ -127,7 +151,10 @@ bool dap_db_history_add(char a_type, pdap_store_obj_t a_store_obj, size_t a_dap_
 }
 
 /**
- * Get last id in log
+ * @brief Gets last id of the log.
+ * 
+ * @param a_group_name a group name string
+ * @return Returns id if succeessful.
  */
 uint64_t dap_db_log_get_group_last_id(const char *a_group_name)
 {
@@ -141,7 +168,9 @@ uint64_t dap_db_log_get_group_last_id(const char *a_group_name)
 }
 
 /**
- * Get last id in log
+ * @brief Gets last id of local.history group.
+ * 
+ * @return Returns id if succeess.
  */
 uint64_t dap_db_log_get_last_id(void)
 {
@@ -149,8 +178,10 @@ uint64_t dap_db_log_get_last_id(void)
 }
 
 /**
- * Thread for reading log list
- * instead dap_db_log_get_list()
+ * @brief A function for a thread for reading a log list
+ * 
+ * @param arg a pointer to the log list structure
+ * @return Returns NULL.
  */
 static void *s_list_thread_proc(void *arg)
 {
@@ -218,7 +249,12 @@ static void *s_list_thread_proc(void *arg)
 }
 
 /**
- * instead dap_db_log_get_list()
+ * @brief Starts a thread that readding a log list
+ * @note instead dap_db_log_get_list()
+ * 
+ * @param a_addr a pointer to the structure
+ * @param a_flags flags
+ * @return Returns a pointer to the log list structure if successful, otherwise NULL pointer.
  */
 dap_db_log_list_t* dap_db_log_list_start(dap_chain_node_addr_t a_addr, int a_flags)
 {
@@ -260,7 +296,10 @@ dap_db_log_list_t* dap_db_log_list_start(dap_chain_node_addr_t a_addr, int a_fla
 }
 
 /**
- * Get number of items
+ * @brief Gets a number of objects from a log list.
+ * 
+ * @param a_db_log_list a pointer to the log list structure
+ * @return Returns the number if successful, otherwise 0.
  */
 size_t dap_db_log_list_get_count(dap_db_log_list_t *a_db_log_list)
 {
@@ -273,6 +312,12 @@ size_t dap_db_log_list_get_count(dap_db_log_list_t *a_db_log_list)
     return l_items_number;
 }
 
+/**
+ * @brief Gets a number of rest objects from a log list.
+ * 
+ * @param a_db_log_list a pointer to the log list structure
+ * @return Returns the number if successful, otherwise 0.
+ */
 size_t dap_db_log_list_get_count_rest(dap_db_log_list_t *a_db_log_list)
 {
     if(!a_db_log_list)
@@ -283,10 +328,13 @@ size_t dap_db_log_list_get_count_rest(dap_db_log_list_t *a_db_log_list)
     pthread_mutex_unlock(&a_db_log_list->list_mutex);
     return l_items_rest;
 }
+
 /**
- * Get one item from log_list
+ * @brief Gets an object from a list.
+ * 
+ * @param a_db_log_list a pointer to the log list
+ * @return Returns a pointer to the object.
  */
-
 dap_db_log_list_obj_t *dap_db_log_list_get(dap_db_log_list_t *a_db_log_list)
 {
     if(!a_db_log_list)
@@ -318,6 +366,12 @@ dap_db_log_list_obj_t *dap_db_log_list_get(dap_db_log_list_t *a_db_log_list)
     return l_list ? (dap_db_log_list_obj_t *)l_list->data : NULL;
 }
 
+/**
+ * @brief Deallocates memory of a list item
+ * 
+ * @param a_item a pointer to the list item
+ * @returns (none)
+ */
 void dap_db_log_list_delete_item(void *a_item)
 {
     dap_db_log_list_obj_t *l_list_item = (dap_db_log_list_obj_t *)a_item;
@@ -326,7 +380,10 @@ void dap_db_log_list_delete_item(void *a_item)
 }
 
 /**
- * Get log diff as list_write
+ * @brief Deallocates memory of a log list.
+ * 
+ * @param a_db_log_list a pointer to the log list structure
+ * @returns (none)
  */
 void dap_db_log_list_delete(dap_db_log_list_t *a_db_log_list)
 {
diff --git a/modules/global-db/dap_chain_global_db_remote.c b/modules/global-db/dap_chain_global_db_remote.c
index 8bed4f838c9c191b7a8d2dbc0cd68d7558ff674c..3c51d5bec51b247045e1f4041e8fb7957ed6162f 100644
--- a/modules/global-db/dap_chain_global_db_remote.c
+++ b/modules/global-db/dap_chain_global_db_remote.c
@@ -15,9 +15,9 @@
 #define NODE_TIME_EXPIRED_DEFAULT 720
 
 /**
- * @brief Sets current node adress
+ * @brief Sets a current node adress.
  * @param a_address a current node adress
- * @param a_net_name a net name
+ * @param a_net_name a net name string
  * @return True if success, otherwise false
  */
 static bool dap_db_set_cur_node_addr_common(uint64_t a_address, char *a_net_name, time_t a_expire_time)
@@ -39,7 +39,11 @@ static bool dap_db_set_cur_node_addr_common(uint64_t a_address, char *a_net_name
 }
 
 /**
- * Set addr for current node and no expire time
+ * @brief Sets an adress of a current node and no expire time.
+ * 
+ * @param a_address an adress of a current node
+ * @param a_net_name a net name string
+ * @return Returns true if siccessful, otherwise false
  */
 bool dap_db_set_cur_node_addr(uint64_t a_address, char *a_net_name )
 {
@@ -47,7 +51,11 @@ bool dap_db_set_cur_node_addr(uint64_t a_address, char *a_net_name )
 }
 
 /**
- * Set addr for current node and expire time
+ * @brief Sets an adress of a current node and expire time.
+ * 
+ * @param a_address an adress of a current node
+ * @param a_net_name a net name string
+ * @return Returns true if siccessful, otherwise false
  */
 bool dap_db_set_cur_node_addr_exp(uint64_t a_address, char *a_net_name )
 {
@@ -55,10 +63,11 @@ bool dap_db_set_cur_node_addr_exp(uint64_t a_address, char *a_net_name )
     return dap_db_set_cur_node_addr_common(a_address,a_net_name,l_cur_time);
 }
 
-
-
 /**
- * Get addr for current node
+ * @brief Gets an adress of current node by a net name.
+ * 
+ * @param a_net_name a net name string
+ * @return Returns an adress if successful, otherwise 0.
  */
 uint64_t dap_db_get_cur_node_addr(char *a_net_name)
 {
@@ -105,7 +114,12 @@ uint64_t dap_db_get_cur_node_addr(char *a_net_name)
 }
 
 /**
- * Set last id for remote node
+ * @brief Sets last id of a remote node.
+ * 
+ * @param a_node_addr a node adress
+ * @param a_id id
+ * @param a_group a group name string
+ * @return Returns true if successful, otherwise false.
  */
 bool dap_db_set_last_id_remote(uint64_t a_node_addr, uint64_t a_id, char *a_group)
 {
@@ -119,7 +133,11 @@ bool dap_db_set_last_id_remote(uint64_t a_node_addr, uint64_t a_id, char *a_grou
 }
 
 /**
- * Get last id for remote node
+ * @brief Gets last id of a remote node.
+ * 
+ * @param a_node_addr a node adress
+ * @param a_group a group name string
+ * @return Returns id if successful, otherwise 0.
  */
 uint64_t dap_db_get_last_id_remote(uint64_t a_node_addr, char *a_group)
 {
@@ -138,7 +156,13 @@ uint64_t dap_db_get_last_id_remote(uint64_t a_node_addr, char *a_group)
 }
 
 /**
- * Set last hash for chain for remote node
+ * @brief Sets the last hash of a remote node.
+ * 
+ * @param a_node_addr a node adress
+ * @param a_chain a pointer to the chain stucture
+ * @param a_hash a 
+ * @return true 
+ * @return false 
  */
 bool dap_db_set_last_hash_remote(uint64_t a_node_addr, dap_chain_t *a_chain, dap_chain_hash_fast_t *a_hash)
 {
@@ -147,7 +171,11 @@ bool dap_db_set_last_hash_remote(uint64_t a_node_addr, dap_chain_t *a_chain, dap
 }
 
 /**
- * Get last hash for chain for remote node
+ * @brief Gets the last hash of a remote node.
+ * 
+ * @param a_node_addr a node adress
+ * @param a_chain a pointer to a chain structure
+ * @return Returns a hash if successful.
  */
 dap_chain_hash_fast_t *dap_db_get_last_hash_remote(uint64_t a_node_addr, dap_chain_t *a_chain)
 {
@@ -159,6 +187,12 @@ dap_chain_hash_fast_t *dap_db_get_last_hash_remote(uint64_t a_node_addr, dap_cha
     return (dap_chain_hash_fast_t *)l_hash;
 }
 
+/**
+ * @brief Gets a size of an object.
+ * 
+ * @param store_obj a pointer to the object
+ * @return Returns the size.
+ */
 static size_t dap_db_get_size_pdap_store_obj_t(pdap_store_obj_t store_obj)
 {
     size_t size = sizeof(uint32_t) + 2 * sizeof(uint16_t) + sizeof(time_t)
@@ -168,10 +202,10 @@ static size_t dap_db_get_size_pdap_store_obj_t(pdap_store_obj_t store_obj)
 }
 
 /**
- * serialization
- * @param a_old_pkt an object for multiplexation
- * @param a_new_pkt an object for multiplexation
- * @return NULL in case of an error
+ * @brief Multiples data into a_old_pkt structure from a_new_pkt structure.
+ * @param a_old_pkt a pointer to the old object
+ * @param a_new_pkt a pointer to the new object 
+ * @return Returns a pointer to the multiple object
  */
 dap_store_obj_pkt_t *dap_store_packet_multiple(dap_store_obj_pkt_t *a_old_pkt, dap_store_obj_pkt_t *a_new_pkt)
 {
@@ -188,6 +222,13 @@ dap_store_obj_pkt_t *dap_store_packet_multiple(dap_store_obj_pkt_t *a_old_pkt, d
     return a_old_pkt;
 }
 
+/**
+ * @brief Changes id in a packed structure.
+ * 
+ * @param a_pkt a pointer to the packed structure
+ * @param a_id id
+ * @return (none)
+ */
 void dap_store_packet_change_id(dap_store_obj_pkt_t *a_pkt, uint64_t a_id)
 {
     uint16_t l_gr_len;
@@ -197,9 +238,9 @@ void dap_store_packet_change_id(dap_store_obj_pkt_t *a_pkt, uint64_t a_id)
 }
 
 /**
- * serialization
- * @param a_store_obj an object for serialization
- * @return NULL in case of an error
+ * @brief Serializes an object into a packed structure.
+ * @param a_store_obj a pointer to the object to be serialized
+ * @return Returns a pointer to the packed sructure if successful, otherwise NULL.
  */
 dap_store_obj_pkt_t *dap_store_packet_single(pdap_store_obj_t a_store_obj)
 {
@@ -235,12 +276,13 @@ dap_store_obj_pkt_t *dap_store_packet_single(pdap_store_obj_t a_store_obj)
     assert(l_offset == l_data_size_out);
     return l_pkt;
 }
+
 /**
- * deserialization
- * @param store_obj_count[out] count of the output structures store_obj
- * @return NULL in case of an error*
+ * @brief Deserializes some objects from a packed structure into an array of objects.
+ * @param pkt a pointer to the serialized packed structure
+ * @param store_obj_count[out] a number of deserialized objects in the array
+ * @return Returns a pointer to the first object in the array, if successful; otherwise NULL.
  */
-
 dap_store_obj_t *dap_store_unpacket_multiple(const dap_store_obj_pkt_t *pkt, size_t *store_obj_count)
 {
     if(!pkt || pkt->data_size < 1)