diff --git a/data/apiclient.go b/data/apiclient.go
index 0971ba3..a1f6552 100644
--- a/data/apiclient.go
+++ b/data/apiclient.go
@@ -47,7 +47,7 @@ func (a *ApiClient) Call(method, route string, requestBody io.Reader, useKey boo
 
 	if useKey {
 		if a.Key == "" {
-			return response, fmt.Errorf("Call to API required a key but none was provided. See --help for instructions on providing an API key.")
+			return response, fmt.Errorf("L'appel au serveur API requiert une clé, mais aucune n'était donnée. Voir --help pour les instructions sur comment fournir une clé API.")
 		}
 
 		request.Header.Add("Authorization", fmt.Sprintf("Bearer %s", a.Key))
@@ -87,7 +87,7 @@ func (a *ApiClient) GetHealth() (string, error) {
 	}
 
 	if response.Message == "" {
-		return response.Message, errors.New("Could not confirm that API server is up, no response message")
+		return response.Message, errors.New("Impossible de confirmer l'état du serveur API.")
 	}
 
 	return response.Message, nil
diff --git a/data/dataclient.go b/data/dataclient.go
index 2398bd0..8715e89 100644
--- a/data/dataclient.go
+++ b/data/dataclient.go
@@ -87,7 +87,7 @@ func (d *DataClient) InsertTransactions(transactions []models.Transaction) ([]mo
 		// Check values
 		if transaction.MembreID == "" {
 			tx.Rollback()
-			return rowsInserted, errors.New("Cannot insert transaction with no membre_id")
+			return rowsInserted, errors.New("Impossible d'insérer une transaction sans membre_id")
 		}
 
 		rows, err := tx.NamedQuery("INSERT INTO transactions (membre_id, given_at, is_perpetual) VALUES (:membre_id, current_timestamp, :is_perpetual) RETURNING id, membre_id, is_perpetual;", &transaction)
@@ -126,7 +126,7 @@ func (d *DataClient) GetTransaction(membreID string, is_perpetual bool) (models.
 	}
 
 	if transaction.ID == "" {
-		return transaction, fmt.Errorf("No transaction found")
+		return transaction, fmt.Errorf("Aucune transaction trouvée")
 	}
 
 	return transaction, nil
diff --git a/handlers/transaction.go b/handlers/transaction.go
index ecd20d9..c6c6a15 100644
--- a/handlers/transaction.go
+++ b/handlers/transaction.go
@@ -19,7 +19,7 @@ func GetTransactions(c echo.Context) error {
 
 	client, err := data.NewDataClientFromViper()
 	if err != nil {
-		response.Message = fmt.Sprintf("Error during data.NewDataClientFromViper(): %s", err)
+		response.Message = fmt.Sprintf("Erreur pendant data.NewDataClientFromViper(): %s", err)
 
 		return c.JSON(statusCode, response)
 	}
@@ -28,19 +28,19 @@ func GetTransactions(c echo.Context) error {
 	transactions, err := client.ListTransactions()
 	response.Data.Transactions = transactions
 	if err != nil {
-		response.Message = fmt.Sprintf("Error during client.ListTransactions(): %s", err)
+		response.Message = fmt.Sprintf("Erreur pendant client.ListTransactions(): %s", err)
 
 		return c.JSON(statusCode, response)
 	}
 
 	if len(transactions) == 0 {
-		response.Message = "No transactions found"
+		response.Message = "Aucune transaction trouvée"
 		statusCode = http.StatusNotFound
 
 		return c.JSON(statusCode, response)
 	}
 
-	response.Message = "List successful"
+	response.Message = "Liste complétée"
 	statusCode = http.StatusOK
 
 	return c.JSON(statusCode, response)
@@ -55,21 +55,21 @@ func PostTransactions(c echo.Context) error {
 
 	if err := c.Bind(&transactions); err != nil {
 		statusCode = http.StatusBadRequest
-		response.Message = fmt.Sprintf("Error during c.Bind(): %s", err)
+		response.Message = fmt.Sprintf("Erreur pendant c.Bind(): %s", err)
 
 		return c.JSON(statusCode, response)
 	}
 
 	client, err := data.NewDataClientFromViper()
 	if err != nil {
-		response.Message = fmt.Sprintf("Error during data.NewDataClientFromViper(): %s", err)
+		response.Message = fmt.Sprintf("Erreur pendant data.NewDataClientFromViper(): %s", err)
 
 		return c.JSON(statusCode, response)
 	}
 	defer client.DB.Close()
 
 	if len(transactions) == 0 {
-		response.Message = fmt.Sprintf("Nothing to do")
+		response.Message = fmt.Sprintf("Rien à faire")
 		statusCode = http.StatusOK
 
 		return c.JSON(statusCode, response)
@@ -91,20 +91,20 @@ func PostTransactions(c echo.Context) error {
 	// Check if membre_id exists according to bottin
 	for _, transaction := range transactions {
 		if transaction.MembreID == "" {
-			response.Message = fmt.Sprintf("Cannot insert transaction without a membre_id")
+			response.Message = fmt.Sprintf("Impossible d'insérer une transaction sans membre_id (numéro étudiant)")
 			statusCode = http.StatusBadRequest
 
 			return c.JSON(statusCode, response)
 		}
 		membre, err := bottinApiClient.GetMembre(transaction.MembreID)
 		if err != nil {
-			response.Message = fmt.Sprintf("Error during bottinApiClient.GetMembre(): %s", err)
+			response.Message = fmt.Sprintf("Erreur pendant bottinApiClient.GetMembre(): %s", err)
 
 			return c.JSON(statusCode, response)
 		}
 
 		if membre.ID == "" {
-			response.Message = fmt.Sprintf("Cannot insert transaction for non-existent membre %s", membre.ID)
+			response.Message = fmt.Sprintf("Aucun membre avec numéro étudiant '%s' dans le bottin de l'AGECEM", membre.ID)
 			statusCode = http.StatusNotFound
 
 			return c.JSON(statusCode, response)
@@ -118,17 +118,17 @@ func PostTransactions(c echo.Context) error {
 		transaction, err := client.GetTransaction(transaction.MembreID, transaction.IsPerpetual)
 		if err != nil {
 			if err.Error() != "sql: no rows in result set" {
-				response.Message = fmt.Sprintf("Error during client.GetTransaction(): %s", err)
+				response.Message = fmt.Sprintf("Erreur pendant client.GetTransaction(): %s", err)
 			}
 		}
 
 		if transaction.ID != "" {
-			agendaType := "non-perpetual"
+			agendaType := "non-perpétuel"
 			if transaction.IsPerpetual {
-				agendaType = "perpetual"
+				agendaType = "perpétuel"
 			}
 
-			response.Message = fmt.Sprintf("Membre %s already received %s", transaction.MembreID, agendaType)
+			response.Message = fmt.Sprintf("Membre %s a déjà son agenda %s", transaction.MembreID, agendaType)
 
 			statusCode = http.StatusBadRequest
 
@@ -139,13 +139,13 @@ func PostTransactions(c echo.Context) error {
 	insertedTransactions, err := client.InsertTransactions(transactions)
 	response.Data.Transactions = insertedTransactions
 	if err != nil {
-		response.Message = fmt.Sprintf("Error during client.InsertTransactions(): %s", err)
+		response.Message = fmt.Sprintf("Erreur pendant client.InsertTransactions(): %s", err)
 
 		return c.JSON(statusCode, response)
 	}
 
 	statusCode = http.StatusCreated
-	response.Message = "Insert successful"
+	response.Message = "Insertion complétée"
 
 	return c.JSON(statusCode, response)
 }