Useful ABAP resources

Reference

• ABAP Language Documentation
• Clean ABAP Guidelines and cheat-sheet

Learning

• SAP Learning Journey: Get Started with ABAP Programming (free)

Tutorials

• ABAP Platform for Developers (free)

Training

• Free online classes at openSAP in particular Writing Testable Code in ABAP (free)
• SAP Learning Journey and Certification (paid)
• ABAP Academy (paid)

Open Source ABAP

• abapGit
• dotabap.org