Manual PHP

https://www.php.net/manual/pt_BR/

MANUAL MYSQL

https://downloads.mysql.com/docs/refman-4.1-pt.a4.pdf

PHP TESTER

http://phptester.net/

W3Schools

https://www.w3schools.com/

Json Formatter e Validator

https://jsonformatter.curiousconcept.com/#

Free Pragramming Books

https://github.com/EbookFoundation/free-programming-books