Paypal Express- Checkout
This service helps you streamline the checkout process for a buyer. The payment experience is on paypal.com (a redirection from the merchant's site) and then the buyer is returned to the merchant's site for payment confirmation. To use this service, the merchant must have a PayPal Business/Merchant account
Express checkout Payment: https://developer.paypal.com/webapps/developer/docs/classic/express-checkout/gs_expresscheckout/
1. Signup developer.paypal.com using your information and login using your email and password.
Email: muna.physio@gmail.com
Pass: Tashnim#321
2. After login click "My Apps & Credentials" -> "Generate Credential".
3. Generate v.zero Credential Page. Select a "Sandbox developer account". for me muna.physio-facilitator@gmail.com(US). Click "Generate Credential"
4. Credential Generated. 
Sandbox Account: muna.physio-facilitator@gmail.com
Access Token:    access_token$sandbox$pfkpck3b38tsknjg$af2b31c61d2eefe3285cc4211983e0e0
Expiry Date:     07 Nov 2026
5. Logout and Login again.
6. Click "Sandbox". Click on your email address(BUSINESS type) and then click "Profile" link. For me muna.physio-facilitator@gmail.com. 
From the Profile tab collect email id and set a new password. for me it's
Business Email: muna.physio-facilitator@gmail.com
Password: aminulsumon
From the API Credentials tab you get your API credential (Username, Password & Signature). This is your Business Account.
Business Account Username: muna.physio-facilitator_api1.gmail.com
Password: 42R988D6B676SJ52
Signature: AFcWxV21C7fd0v3bYYYRCpSSRl31ADbR0BpkYjJvJ1lRwBwXXmXDlsEh

7. Click on your email address(PERSONAL type) and then click "Profile" link
Buyer Email: muna.physio-buyer@gmail.com
Password: aminulsumon
From the funding tab get bank account and CC info
Bank Account Number: 21139676
Bank Routing Number: 325272063
Credit Card Number: 4032037107806941
Credit Card Type: VISA
Expiration Date: 12/2021

8. I clone buyer account and set the following information
Buyer Email: muna.physio-buyer-1@gmail.com
Password: aminulsumon
Full Name: Buyer Amin
Credit Card Number: 4032037187964826
Credit Card Type: VISA
Expiration Date: 12/2021

Credential for Login Paypal:
https://developer.paypal.com/developer/login
Email: aminulsumon@gmail.com
Pass: Tashnim#123

Credential of Seller(Business Account):
Email: muna.physio-facilitator_api1.gmail.com
Pass : aminulsumon

Credential of Buyer(Buyer Account):
Email: muna.physio-buyer@gmail.com
Pass: aminulsumon



OLDCredential While Purchase: (>>>>>>>>>>>>>> OLD ACCOUNTS START <<<<<<<<<<<<<<<<<<<)
Buyer Info:
Email: aminul-personal1@gmail.com
Password: goodluck01
Email address: aminul-buyer@gmail.com (Not working)
Password: goodluck01
Email address: brown.buyer@gmail.com (Not working)
Password:  goodluck01
You can create "Personal(buyer account)" and "Business(merchant account)" after login at developer.paypal.com (using your actual email & pass during signup) click "Create Account".
Test account can also create from sandbox.paypal.com
(>>>>>>>>>>>>>> OLD ACCOUNTS END <<<<<<<<<<<<<<<<<<<)

PayPal checkout - credit card tab by default
The only way to do that is with Express Checkout. In your SetExpressCheckout request you set SOLUTIONTYPE=Sole and LANDINGPAGE=Billing.

Error and Solution:
===================================
Error: Security header is not valid
Solution: First check your credentials are correct or not(API username, password & signature). if it's correct then make sure you have no proxy in your browser.

Error: SetExpressCheckout failed: Could not resolve host: api-3t.sandbox.paypal.com(6)
Solution: make sure you have no proxy in your browser.

/********************** ELLIOTT PAYPAL INFOMRATION STARTS ****************************/
Paypal.com
user : info@getasnapshot.com
pass : R3set2017

Sandbox Account Credentials:
Username: info-facilitator_api1.getasnapshot.com
Password: ZFHJ77HM94W2DJ4X
Signature: AFcWxV21C7fd0v3bYYYRCpSSRl31ASb3ps2gYLRK5n-8q5uF5Oa9Zjt0

Sandbox Account
Email: info-facilitator@getasnapshot.com
Access Token: access_token$sandbox$b6362cfq44p8b47s$e21c8401a25ed7e9e2188fc748a67831
Expiry Date: 07 Nov 2026

Business/Marchent Credentials
Login Email: info-facilitator@getasnapshot.com
Password: aminyoga

Classic TEST API Credentials
Username:  info-facilitator_api1.getasnapshot.com
Password:  ZFHJ77HM94W2DJ4X
Signature: AFcWxV21C7fd0v3bYYYRCpSSRl31ASb3ps2gYLRK5n-8q5uF5Oa9Zjt0

Buyer Credentials:
Email ID: info-buyer@getasnapshot.com
Password: aminyoga
Bank Account Number: 08850418394
Routing Number: 325272063
Credit Card Number: 4032032762269899
Credit Card Type: VISA
Expiration Date: 12/2021
/********************** ELLIOTT PAYPAL INFOMRATION END ****************************/