This is a list of several apps and websites that I have found to be useful and enjoy using. All of the apps can be found in the App Store on iOS devices; I am not sure about Google Play or any other OS.
The Bible App: Quite possibly one of the best free Bible apps out there. You can browse through hundreds of Bible translations in various languages, highlight, take notes, make text images, follow a Bible reading plan, and lots more.
PocketSword: Probably the fastest Bible app out there. It doesn’t allow highlighting or many of the other features that the Bible App offers, but what it lacks in features it makes up for in content. There are again hundreds of translations to choose from, including various commentaries and study helps. It even has the Hebrew Old Testament and the Greek New Testament, not to mention the Latin Vulgate and various other old translations.
NET Bible Online: The New English Translation (NET) of the Bible is quite the piece of work! It is a dynamic equivalence translation, meaning that it is a looser translation than say, the ESV or the NASB. But what is truly remarkable about this translation is the over 60,000 footnotes explaining the translator’s decisions, significant historical contexts, and textual critical issues. It allows one to look right over the translators’ shoulders as they wrestle with the text of Scripture and attempt to render it in clear, modern English. This translation with all of its notes is also available on the Bible App, and the translation itself with limited notes is available on PocketSword. Print editions are also available. (See also: www.bible.org)
Reformation Network (RefNet): The Reformation Network is an outreach of Ligonier Ministries. It has 24-hours a day, 7 days a week programming from Reformed pastors and Bible teachers, with music and Bible readings thrown in. One of the best segments is Spurgeon’s “Morning and Evening,” played every, well, morning and evening.
Grace to You Sermons: This app has the majority of John MacArthur’s sermons and Bible lessons, along with videos from the various conferences that Dr. MacArthur has put together. Great resource for solid Bible teaching.
Ligonier Ministries: Ligonier Ministries is the brain child of RC Sproul, and on this app you can find most of his teaching series and listen to his daily podcast, Renewing Your Mind. Another excellent resource for solid Reformed Bible teaching.
SermonAudio: SermonAudio is an archive of hundreds of thousands of sermons from across the globe. Any church that uses it will upload its sermons to the website, and they are all available from the app. My favorites are the Phoenix Reformed Baptist Church and Alpha and Omega Ministries. On SermonAudio you can also find various podcasts.
Ask Pastor John: This app is Pastor John Piper’s weekday podcast answering listener questions. Always a great resource for answers to tough questions coming from a good pastor.
Desiring God: John Piper’s ministry, with thousands of sermons available and dozens of books free for download.
John Calvin Commentary App: 22,000 pages of commentary by the one and only John Calvin, condensed into one app. Easily navigable, well laid out, and excellent content. Highly recommended.
Matthew Henry Commentary App: The whole of Matthew Henry’s six volume commentary on the entire Bible put into one beautifully designed app – what more do you need? From the same developer who created the John Calvin commentary app.
Christian Creeds and Reformed Confessions: This app contains several historic creeds and confessions from years gone by, including the Apostle’s Creed, the Athanasian Creed, the Heidelberg Catechism, the Westminster Confession of Faith, and more. Great resource for all your creedal needs.
Alpha and Omega Ministries: The ministry outreach of James White. On their YouTube channel and SermonAudio, Dr. White’s biweekly podcast, “The Dividing Line,” can be heard, as well as the numerous moderated public debates that Dr. White has participated in against Muslims, Mormons, Jehovah’s Witnesses, Roman Catholics, and Atheists. I also suggest you visit his IRC chat channel to fellowship with fellow believers and get questions answered.
The Spurgeon Archive: This excellent resource was created by Phil Johnson. It contains the majority of Spurgeon’s sermons and published works.
Michael Hall’s Theology Blog: Michael Hall is a friend of mine who has proven himself to be a very serious student of the Scriptures. On his blog, he intends to share the truth of the Reformed Christian faith. Not only this, but to provide application of the truths of Scripture to our lives. Michael is a gifted writer and a darn good exegete. You would do well to read his stuff. You can also find him on Instagram: @michaelhalltheology.
BioLogos: This website is chock full of resources pertaining to the intersection of modern day science and biblical faith. Tread carefully, however, because not every article is entirely orthodox in its assertions. What I have found most helpful in understanding the perspective of “evolutionary creationism” is the BioLogos Forum, which invites people from all perspectives (young earth, old earth, atheism, etc.) to converse and dialogue about science and faith.