This "Master English" App is very effective and helpful "All in One tool" for those are studying English Speaking and Grammar in indeed.
Making sure that this app helps you speak fluently and improve your grammar. In this "Master English" application, there are parts such as Speaking Parts and Grammar Parts and in each part, they are categorized into the levels including with quiz sections.
Besides those items can be studied with audio, online and online modes with ease.

>> GRAMMAR PART:
Consisting of main features:
1. Parts of Speech
2. Verb to Be
3. Verb to Have
4. Verb to Do
5. 12 kinds of Tenses
6. Comparison
7. Active & Passive Voices
8. Direct & Indirect Speeches
9. Four Types of Sentences
10. Five Kinds of Clauses
11. 14 kinds of Phrases
12. Inversion Usage
13. General Grammar Sections

>> SPEAKING PART:
Main feature, all with audios:
1. Spoken Patterns (1/2)
2. Basic Listening:
3. Intermediate Listening (1/2)
4. Advance Listening (1/2)
5. Business English
6. Idiom & Phrases
7. Common Phrasal Verbs
8. Daily Conversation
9. Common Expression
10. Common Idiom
11. Interview Lessons

App's Features:
>>Listening & Reading Transcriptions with audio
>>Two listening modes: Online or Offline