Chess Prep - openings trainer by Tomasz Bogun

Web Apps

Catastrophes & Tactics in the Chess Opening - Volume 3: Flank Openings: Winning in 15 Moves or Less: Chess Tactics, Brilliancies & Blunders in the Chess Opening (Winning Quickly at Chess): Hansen

Chess Openings Trainer Pro - Apps on Google Play

GitHub - davidgma/chess-opening-trainer: Obsolete: Training program to help learn chess openings.

FRITZ TRAINER - Basic Opening Strategy

Chess Openings Trainer by Piero Toffanin

Chess Trainer Hub - RagChess

Specialized Chess Opening Tactics - by Hansen, Carsten

CHESS BOOK: CHESS OPENING TRAP OF THE DAY by Bruce Alberston 9781580422178

Dvoretsky: World's Best Chess Trainer - Forward Chess