Is there a sefer, a website, or an app with all the concepts in Shas? Halachic Concepts such as - "Women are exempt from time-bound commandments".
Aspaklaria is very good and it's free.
Please take a look at HaMafteach, I think it fits the description you mentioned. It is in English.
From description of book:
HaMafteach locates for you every topic, saying, anecdote, maxim, parable, significant subject matter, law, Biblical exegesis, and Biblical and Talmudic personality mentioned in the Talmud. The English edition includes a transliteration of Hebrew and Aramaic words and phrases, and a new integrated glossary. Hamafteach is an invaluable sefer for Rebbeim, teachers, authors of seforim, researchers and scholars, as well as for anyone who wishes to swim in the yam shel Talmud.
If you are looking for a "readable book" which you can read from beginning to end to understand key talmudic concepts (rather than a dictionary or encyclopedia), then R Adin Steinsaltz' Reference Guide to the Talmud
clearly and concisely explains the Talmud’s fundamental structure, concepts, terminology, assumptions, and inner logic; provides essential historical and biographical information; and includes appendixes, a key to abbreviations, and a comprehensive index.
Practically it describes talmudic methodology, terminology, hermeneutical principles and halakhic concepts (there are more than 100 pages of these in my edition). It covers "Women are exempt from time-bound commandments" both under "mitzvot" and "women" and they are cross-references in the index.
Kesef Nivchar brings the gemara and primary Rishonim arranged by concept, covering 160 concepts:
http://hebrewbooks.org/19582 (There are newer prints available.)