diff --git a/auth.go b/auth.go
index 5df876c..1b4bdf0 100644
--- a/auth.go
+++ b/auth.go
@@ -7,6 +7,8 @@ import (
 )
 
 // GetAccessToken returns struct of TokenResponse
+// No need to call SetAccessToken to apply new access token for current Client
+// Endpoint: POST /v1/oauth2/token
 func (c *Client) GetAccessToken() (*TokenResponse, error) {
 	buf := bytes.NewBuffer([]byte("grant_type=client_credentials"))
 	req, err := http.NewRequest("POST", fmt.Sprintf("%s%s", c.APIBase, "/v1/oauth2/token"), buf)
@@ -29,6 +31,7 @@ func (c *Client) GetAccessToken() (*TokenResponse, error) {
 }
 
 // GetAuthorization returns an authorization by ID
+// Endpoint: GET /v1/payments/authorization/ID
 func (c *Client) GetAuthorization(authID string) (*Authorization, error) {
 	buf := bytes.NewBuffer([]byte(""))
 	req, err := http.NewRequest("GET", fmt.Sprintf("%s%s", c.APIBase, "/v1/payments/authorization/"+authID), buf)
@@ -48,6 +51,7 @@ func (c *Client) GetAuthorization(authID string) (*Authorization, error) {
 
 // CaptureAuthorization captures and process an existing authorization.
 // To use this method, the original payment must have Intent set to "authorize"
+// Endpoint: POST /v1/payments/authorization/ID/capture
 func (c *Client) CaptureAuthorization(authID string, a *Amount, isFinalCapture bool) (*Capture, error) {
 	isFinalStr := "false"
 	if isFinalCapture {
@@ -70,6 +74,7 @@ func (c *Client) CaptureAuthorization(authID string, a *Amount, isFinalCapture b
 }
 
 // VoidAuthorization voids a previously authorized payment
+// Endpoint: POST /v1/payments/authorization/ID/void
 func (c *Client) VoidAuthorization(authID string) (*Authorization, error) {
 	buf := bytes.NewBuffer([]byte(""))
 	req, err := http.NewRequest("POST", fmt.Sprintf("%s%s", c.APIBase, "/v1/payments/authorization/"+authID+"/void"), buf)
@@ -89,6 +94,7 @@ func (c *Client) VoidAuthorization(authID string) (*Authorization, error) {
 
 // ReauthorizeAuthorization reauthorize a Paypal account payment.
 // PayPal recommends to reauthorize payment after ~3 days
+// Endpoint: POST /v1/payments/authorization/ID/reauthorize
 func (c *Client) ReauthorizeAuthorization(authID string, a *Amount) (*Authorization, error) {
 	buf := bytes.NewBuffer([]byte("{\"amount\":{\"currency\":\"" + a.Currency + "\",\"total\":\"" + a.Total + "\"}}"))
 	req, err := http.NewRequest("POST", fmt.Sprintf("%s%s", c.APIBase, "/v1/payments/authorization/"+authID+"/reauthorize"), buf)
@@ -104,5 +110,4 @@ func (c *Client) ReauthorizeAuthorization(authID string, a *Amount) (*Authorizat
 	}
 
 	return auth, nil
-
 }
diff --git a/before-commit.sh b/before-commit.sh
new file mode 100755
index 0000000..afe577d
--- /dev/null
+++ b/before-commit.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+go fmt ./...
+golint ./...
+go vet ./...
+go test -v ./...
diff --git a/client.go b/client.go
index 35259ab..515edf6 100644
--- a/client.go
+++ b/client.go
@@ -12,6 +12,7 @@ import (
 )
 
 // NewClient returns new Client struct
+// APIBase is a base API URL, for testing you can use paypalsdk.APIBaseSandBox
 func NewClient(clientID string, secret string, APIBase string) (*Client, error) {
 	if clientID == "" || secret == "" || APIBase == "" {
 		return &Client{}, errors.New("ClientID, Secret and APIBase are required to create a Client")
@@ -27,7 +28,8 @@ func NewClient(clientID string, secret string, APIBase string) (*Client, error)
 	}, nil
 }
 
-// SetLogFile func
+// SetLogFile will set/change a full path to a log file
+// If log file is set paypalsdk will log all requests and responses to this file
 func (c *Client) SetLogFile(filepath string) error {
 	c.LogFile = filepath
 
@@ -115,6 +117,7 @@ func (c *Client) NewRequest(method, url string, payload interface{}) (*http.Requ
 	return http.NewRequest(method, url, buf)
 }
 
+// log will dump request and response to the log file
 func (c *Client) log(req *http.Request, resp *http.Response) {
 	if c.LogFile != "" {
 		os.OpenFile(c.LogFile, os.O_CREATE, 0755)
diff --git a/doc.go b/doc.go
index 41a04f9..4170a81 100644
--- a/doc.go
+++ b/doc.go
@@ -1,6 +1,6 @@
 /*
 Package paypalsdk provides a warepper to PayPal API (https://developer.paypal.com/webapps/developer/docs/api/).
-The first thing you do is to create a Client.
+The first thing you do is to create a Client (you can select API base URL using paypalsdk contsnts).
   c, err := paypalsdk.NewClient("clientID", "secretID", paypalsdk.APIBaseSandBox)
 Then you can get an access token from PayPal:
   accessToken, err := c.GetAccessToken()
diff --git a/order.go b/order.go
index 9ed6dfe..5c64e97 100644
--- a/order.go
+++ b/order.go
@@ -2,7 +2,8 @@ package paypalsdk
 
 import "fmt"
 
-// GetOrder retreives order
+// GetOrder retreives order by ID
+// Endpoint: GET /v1/payments/orders/ID
 func (c *Client) GetOrder(orderID string) (*Order, error) {
 	order := &Order{}
 
@@ -19,7 +20,8 @@ func (c *Client) GetOrder(orderID string) (*Order, error) {
 	return order, nil
 }
 
-// AuthorizeOrder POST /v1/payments/orders/<Order-Id>/authorize
+// AuthorizeOrder - Use this call to authorize an order.
+// Endpoint: POST /v1/payments/orders/ID/authorize
 func (c *Client) AuthorizeOrder(orderID string, amount *Amount) (*Authorization, error) {
 	type authRequest struct {
 		Amount *Amount `json:"amount"`
@@ -40,7 +42,8 @@ func (c *Client) AuthorizeOrder(orderID string, amount *Amount) (*Authorization,
 	return auth, nil
 }
 
-// CaptureOrder POST /v1/payments/orders/<Order-Id>/capture
+// CaptureOrder - Use this call to capture a payment on an order. To use this call, an original payment call must specify an intent of order.
+// Endpoint: POST /v1/payments/orders/ID/capture
 func (c *Client) CaptureOrder(orderID string, amount *Amount, isFinalCapture bool, currency *Currency) (*Capture, error) {
 	type captureRequest struct {
 		Amount         *Amount   `json:"amount"`
@@ -63,7 +66,9 @@ func (c *Client) CaptureOrder(orderID string, amount *Amount, isFinalCapture boo
 	return capture, nil
 }
 
-// VoidOrder POST /v1/payments/orders/<Order-Id>/do-void
+// VoidOrder - Use this call to void an existing order.
+// Note: An order cannot be voided if payment has already been partially or fully captured.
+// Endpoint: POST /v1/payments/orders/ID/do-void
 func (c *Client) VoidOrder(orderID string) (*Order, error) {
 	order := &Order{}
 
diff --git a/payment.go b/payment.go
index a667244..3a8dbe8 100644
--- a/payment.go
+++ b/payment.go
@@ -12,14 +12,15 @@ type ListPaymentsResp struct {
 	Payments []Payment `json:"payments"`
 }
 
-// CreatePaymentResp returned by CreatePayment
+// CreatePaymentResp contains Payment Info and Links slice
 type CreatePaymentResp struct {
 	*Payment
 	Links []Links `json:"links"`
 }
 
-// CreateDirectPaypalPayment sends request with payment
+// CreateDirectPaypalPayment sends request to create a payment with payment_method=paypal
 // CreatePayment is more common function for any kind of payment
+// Endpoint: POST /v1/payments/payment
 func (c *Client) CreateDirectPaypalPayment(amount Amount, redirectURI string, cancelURI string, description string) (*PaymentResponse, error) {
 	buf := bytes.NewBuffer([]byte("{\"intent\":\"sale\",\"payer\":{\"payment_method\":\"paypal\"}," +
 		"\"transactions\":[{\"amount\":{\"total\":\"" + amount.Total +
@@ -47,6 +48,8 @@ func (c *Client) CreateDirectPaypalPayment(amount Amount, redirectURI string, ca
 }
 
 // CreatePayment creates a payment in Paypal
+// Depending on the payment_method and the funding_instrument, you can use the payment resource for direct credit card payments, stored credit card payments, or PayPal account payments.
+// Endpoint: POST /v1/payments/payment
 func (c *Client) CreatePayment(p Payment) (*CreatePaymentResp, error) {
 	req, err := c.NewRequest("POST", fmt.Sprintf("%s%s", c.APIBase, "/v1/payments/payment"), p)
 	if err != nil {
@@ -63,7 +66,8 @@ func (c *Client) CreatePayment(p Payment) (*CreatePaymentResp, error) {
 	return response, nil
 }
 
-// ExecuteApprovedPayment executes approved payment
+// ExecuteApprovedPayment - Use this call to execute (complete) a PayPal payment that has been approved by the payer. You can optionally update transaction information when executing the payment by passing in one or more transactions.
+// Endpoint: POST /v1/payments/payment/paymentID/execute
 func (c *Client) ExecuteApprovedPayment(paymentID string, payerID string) (*ExecuteResponse, error) {
 	buf := bytes.NewBuffer([]byte("{\"payer_id\":\"" + payerID + "\"}"))
 	req, err := http.NewRequest("POST", fmt.Sprintf("%s%s", c.APIBase, "/v1/payments/payment/"+paymentID+"/execute"), buf)
@@ -88,6 +92,7 @@ func (c *Client) ExecuteApprovedPayment(paymentID string, payerID string) (*Exec
 }
 
 // GetPayment gets a payment from PayPal
+// Endpoint: GET /v1/payments/payment/ID
 func (c *Client) GetPayment(paymentID string) (*Payment, error) {
 	p := Payment{}
 
@@ -109,6 +114,7 @@ func (c *Client) GetPayment(paymentID string) (*Payment, error) {
 }
 
 // GetPayments retrieve payments resources from Paypal
+// Endpoint: GET /v1/payments/payment/
 func (c *Client) GetPayments() ([]Payment, error) {
 	var p ListPaymentsResp
 
diff --git a/sale.go b/sale.go
index c16f114..1fe6e0e 100644
--- a/sale.go
+++ b/sale.go
@@ -3,6 +3,9 @@ package paypalsdk
 import "fmt"
 
 // GetSale returns a sale by ID
+// Use this call to get details about a sale transaction.
+// Note: This call returns only the sales that were created via the REST API.
+// Endpoint: GET /v1/payments/sale/ID
 func (c *Client) GetSale(saleID string) (*Sale, error) {
 	sale := &Sale{}
 
@@ -20,7 +23,8 @@ func (c *Client) GetSale(saleID string) (*Sale, error) {
 }
 
 // RefundSale refunds a completed payment.
-// Amount can be sent to make a partial refund only
+// Use this call to refund a completed payment. Provide the sale_id in the URI and an empty JSON payload for a full refund. For partial refunds, you can include an amount.
+// Endpoint: POST /v1/payments/sale/ID/refund
 func (c *Client) RefundSale(saleID string, a *Amount) (*Refund, error) {
 	type refundRequest struct {
 		Amount *Amount `json:"amount"`
@@ -42,6 +46,8 @@ func (c *Client) RefundSale(saleID string, a *Amount) (*Refund, error) {
 }
 
 // GetRefund by ID
+// Use it to look up details of a specific refund on direct and captured payments.
+// Endpoint: GET /v1/payments/refund/ID
 func (c *Client) GetRefund(refundID string) (*Refund, error) {
 	refund := &Refund{}
 
diff --git a/types.go b/types.go
index 2614a31..212683f 100644
--- a/types.go
+++ b/types.go
@@ -15,7 +15,7 @@ const (
 )
 
 type (
-	// Address struct
+	// Address https://developer.paypal.com/webapps/developer/docs/api/#address-object
 	Address struct {
 		Line1       string `json:"line1"`
 		Line2       string `json:"line2,omitempty"`
@@ -26,13 +26,13 @@ type (
 		Phone       string `json:"phone,omitempty"`
 	}
 
-	// Amount to pay
+	// Amount https://developer.paypal.com/webapps/developer/docs/api/#amount-object
 	Amount struct {
 		Currency string `json:"currency"`
 		Total    string `json:"total"`
 	}
 
-	// Authorization represetns PayPal authorization
+	// Authorization rhttps://developer.paypal.com/webapps/developer/docs/api/#authorization-object
 	Authorization struct {
 		Amount                    *Amount    `json:"amount,omitempty"`
 		CreateTime                *time.Time `json:"create_time,omitempty"`
@@ -47,7 +47,7 @@ type (
 		ProtectionEligibilityType string     `json:"protection_eligibility_type,omitempty"`
 	}
 
-	// Capture struct
+	// Capture https://developer.paypal.com/webapps/developer/docs/api/#capture-object
 	Capture struct {
 		Amount         *Amount    `json:"amount,omitempty"`
 		IsFinalCapture bool       `json:"is_final_capture"`
@@ -69,7 +69,7 @@ type (
 		Token    *TokenResponse
 	}
 
-	// CreditCard struct
+	// CreditCard https://developer.paypal.com/webapps/developer/docs/api/#creditcard-object
 	CreditCard struct {
 		ID             string   `json:"id,omitempty"`
 		PayerID        string   `json:"payer_id,omitempty"`
@@ -85,7 +85,7 @@ type (
 		ValidUntil     string   `json:"valid_until,omitempty"`
 	}
 
-	// CreditCardToken struct
+	// CreditCardToken https://developer.paypal.com/webapps/developer/docs/api/#creditcardtoken-object
 	CreditCardToken struct {
 		CreditCardID string `json:"credit_card_id"`
 		PayerID      string `json:"payer_id,omitempty"`
@@ -100,7 +100,7 @@ type (
 		Value    string `json:"value,omitempty"`
 	}
 
-	// ErrorResponse is used when a response has errors
+	// ErrorResponse https://developer.paypal.com/webapps/developer/docs/api/#error-object
 	ErrorResponse struct {
 		Response        *http.Response `json:"-"`
 		Name            string         `json:"name"`
@@ -110,7 +110,7 @@ type (
 		Details         []ErrorDetail  `json:"details"`
 	}
 
-	// ErrorDetail map to error_details object
+	// ErrorDetail https://developer.paypal.com/webapps/developer/docs/api/#errordetails-object
 	ErrorDetail struct {
 		Field string `json:"field"`
 		Issue string `json:"issue"`
@@ -123,13 +123,13 @@ type (
 		State string        `json:"state"`
 	}
 
-	// FundingInstrument struct
+	// FundingInstrument https://developer.paypal.com/webapps/developer/docs/api/#fundinginstrument-object
 	FundingInstrument struct {
 		CreditCard      *CreditCard      `json:"credit_card,omitempty"`
 		CreditCardToken *CreditCardToken `json:"credit_card_token,omitempty"`
 	}
 
-	// Item struct
+	// Item https://developer.paypal.com/webapps/developer/docs/api/#item-object
 	Item struct {
 		Quantity    int    `json:"quantity"`
 		Name        string `json:"name"`
@@ -146,7 +146,7 @@ type (
 		ShippingAddress *ShippingAddress `json:"shipping_address,omitempty"`
 	}
 
-	// Links struct
+	// Links https://developer.paypal.com/webapps/developer/docs/api/#itemlist-object
 	Links struct {
 		Href    string `json:"href"`
 		Rel     string `json:"rel"`
@@ -166,7 +166,7 @@ type (
 		Links         []Links    `json:"links,omitempty"`
 	}
 
-	// Payer struct
+	// Payer https://developer.paypal.com/webapps/developer/docs/api/#payer-object
 	Payer struct {
 		PaymentMethod      string              `json:"payment_method"`
 		FundingInstruments []FundingInstrument `json:"funding_instruments,omitempty"`
@@ -174,7 +174,7 @@ type (
 		Status             string              `json:"payer_status,omitempty"`
 	}
 
-	// PayerInfo struct
+	// PayerInfo https://developer.paypal.com/webapps/developer/docs/api/#itemlist-object
 	PayerInfo struct {
 		Email           string           `json:"email,omitempty"`
 		FirstName       string           `json:"first_name,omitempty"`
@@ -186,7 +186,7 @@ type (
 		TaxID           string           `json:"tax_id,omitempty"`
 	}
 
-	// Payment struct
+	// Payment https://developer.paypal.com/webapps/developer/docs/api/#payment-object
 	Payment struct {
 		Intent              string        `json:"intent"`
 		Payer               *Payer        `json:"payer"`
@@ -199,7 +199,7 @@ type (
 		ExperienceProfileID string        `json:"experience_profile_id,omitempty"`
 	}
 
-	// PaymentLink structure
+	// PaymentLink https://developer.paypal.com/webapps/developer/docs/api/#paymentlink-object
 	PaymentLink struct {
 		Href string `json:"href"`
 		Rel  string `json:"rel"`
@@ -211,13 +211,13 @@ type (
 		Links []PaymentLink `json:"links"`
 	}
 
-	// RedirectURLs for redirect_urls
+	// RedirectURLs https://developer.paypal.com/webapps/developer/docs/api/#redirecturls-object
 	RedirectURLs struct {
 		ReturnURL string `json:"return_url,omitempty"`
 		CancelURL string `json:"cancel_url,omitempty"`
 	}
 
-	// Refund will be returned by RefundSale
+	// Refund https://developer.paypal.com/webapps/developer/docs/api/#refund-object
 	Refund struct {
 		ID            string     `json:"id,omitempty"`
 		Amount        *Amount    `json:"amount,omitempty"`
@@ -228,7 +228,7 @@ type (
 		UpdateTime    *time.Time `json:"update_time,omitempty"`
 	}
 
-	// Sale will be returned by GetSale
+	// Sale https://developer.paypal.com/webapps/developer/docs/api/#sale-object
 	Sale struct {
 		ID                        string     `json:"id,omitempty"`
 		Amount                    *Amount    `json:"amount,omitempty"`
@@ -246,7 +246,7 @@ type (
 		Links                     []Links    `json:"links,omitempty"`
 	}
 
-	// ShippingAddress for shipping_address
+	// ShippingAddress https://developer.paypal.com/webapps/developer/docs/api/#shippingaddredd-object
 	ShippingAddress struct {
 		RecipientName string `json:"recipient_name,omitempty"`
 		Type          string `json:"type,omitempty"`
@@ -266,7 +266,7 @@ type (
 		Type         string `json:"token_type"`
 	}
 
-	// Transaction is for transaction object
+	// Transaction https://developer.paypal.com/webapps/developer/docs/api/#transaction-object
 	Transaction struct {
 		Amount         *Amount   `json:"amount"`
 		Description    string    `json:"description,omitempty"`