Texts

• Codex Alexandrinus (facsimile flipbook)
• Codex Sinaiticus (manuscript images and transcriptions, OT LXX [partial] and NT)
• Codex Vaticanus (flipbook)
• Old Testament in Greek, 9 vols. (Brooke, McLean) - Genesis to Esther, Esdras, Judith, and Tobit. Includes extensive textual notes.
• Origenis Hexaplorum quae supersunt (Hebrew, transliterated Greek, Aquila and Symmachus texts of the LXX), v. 1 ; v. 2 (Internet Archive flipbook, v.1, v.2)
• Septuagint version of the Old Testament (Brenton) - Greek text with English translation.
• Septuaginta - (Rahlfs, 2nd ed.) Text only. No critical apparatus.
• Swete, The Old Testament in Greek according to the Septuagint, v.1, v.2, v.3 (1895-1899)

Translations

• New English Translation of the Septuagint
• Septuagint version of the Old Testament (Brenton) - Greek text with English translation.

Concordances

• Hatch & Redpath. Concordance of the Septuagint (1892), vol.1 ; vol. 2 (PDF downloads available for each volume.)
• Hatch & Redpath, Concordance of the Septuagint (Supplement volume)

Introductions/Grammar

• LXX with parsing
• Oxford Handbook of the Septuagint
• Swete, An Introduction to the Old Testament in Greek (1900; copy is 1989 reprint)
• Swete, The Old Testament in Greek according to the Septuagint, v.1, v.2, v.3 (1895-1899)
• Thackeray, Grammar of the OT in Greek, according to the Septuagint (v.1, 1909)

• Dead Seas Scrolls Electronic library Biblical texts (Brill)

  Contains high resolution images of the Biblical Dead Sea Scrolls and all the texts, in the original languages and in translation.

• Dead Seas Scrolls Electronic library Non-Biblical texts (Brill) Contains high resolution images of the Non-Biblical Dead Sea Scroll fragments and all the texts, in the original languages and in translation.

• Dictionary of Qumran Aramaic
• Digital Dead Sea Scrolls 
  High resolution, interactive images of many of the major scrolls in original form, including clickable translation.
• Discoveries in the Judaean Desert Index 

• Inventory of Manuscripts from Qumran 

• Leon Levy Dead Sea Scrolls Digital Library 

  "The Israel Antiquities Authority (IAA) is very proud to present the Leon Levy Dead Sea Scrolls Digital Library, a free online digitized virtual library of the Dead Sea Scrolls. Hundreds of manuscripts made up of thousands of fragments – discovered from 1947 and until the early 1960’s in the Judean Desert along the western shore of the Dead Sea – are now available to the public online. The high resolution images are extremely detailed and can be accessed through various search options on the site."

• Orion Study Center for the Study of the Dead Sea Scrolls and Associated Literature 

  Not a searchable index to DJD but it provides tables of contents to each volume to assist in the difficult task of discerning which text is in which volume. Click on each volume's title link.

Aramaic

• Comprehansive Aramaic Lexicon (Hebrew Union College; use navigation links in left column to search)
• Cook, Dictionary of Qumran Aramaic (2015)
• Dictionary of the Targumim, the Talmud...(Jastrow, 1903)
• Marshall, Manual of the Aramaic Language of the Palestinian Talmud (1929)

Syriac

• Brock, Pocket Gorgias Syriac-English Dictionary (1917)
• Coakley, Robinson's Paradigms and Exercises in Syriac Grammar (2013)
• Luzzatto, Grammar of the Biblical Chaldaic Language and the Talmud Babli idioms (1876)
• Noeldeke, Compendious Syriac Grammar (1904)
• Payne Smith, Compendious Syriac Dictionary, (1903)

• ACU Ancient Coins Collection
  High quality images and extensive descriptions.

• Electronic Text Corpus of Sumerian Literature
  Transliterated and translated texts, fully searchable
• Electronic Tools and Ancient Near East Archives
• Leuven Database of Ancient Books (Trismegistos)

Lexica

• 2-Letter Lookup - Simplified lexicon lookup (Hebrew, Greek, etc.) using multiple lexicons.
• GNT Reader - Click on any Greek word to get parsing and lexical information in right sidebar.
• Greek-English Reference Manual to the Vocabulary of the Greek New Testament - Entries provide Greek word, number of occurrences, Strong's number, grammatical information, pronunciation, and English translation.
• Greek Dictionary (Mounce)
• lexidium - Greek and Latin lexicon compiled from numerous existing lexica
• Louw & Nida, Semantic Dictionary of New Testament Greek
• Manual Greek Lexicon of the New Testament (Abbott-Smith, 1922)
• Vocabulary of the Greek Testament (Moulton, 1929)
• Online Lidell-Scott-Jones Greek-English Lexicon (Classical Greek; note that the Greek language examples are keyed to Thesaurus Linguae Graecae, requiring a login to see them.)

Grammar

• Concise Exegetical Grammar of NT Greek (Greenlee, 2012)
• Elementary New Testament Greek (Dongell, 2014)
• Going Deeper with New Testament Greek - Intermediate Grammar (Kostenberger et al., 2020)
• The Greek New Testament Analyzed - Parsing for  NT Greek words (Guillemette, 1986)
• Intermediate Greek Grammar (Mathewson, 2016 - Full text link on the left)
• Pedalion - Greek grammatical index that "moves between the language’s formal, semantic, and syntactic levels, so as to overcome the static character of a traditional grammar." Very helpful. 
• Syntax of the Moods and Tenses in New Testament Greek (Burton, 3rd ed., 1898)

Thesaurus Linguae Graecae (TLG)  [create a personal account or log into it, upper right]  ||    Video Tutorials for TLG
Database in Greek of all known ancient Greek writings up to 600 A.D. Allows the user to search for Greek words or phrases as they were used in a particular writer or work or time period, resulting in excerpts, a few lines long, of all passages that embody the particular word(s) that have been searched.
Note that when you first log into TLG, you will be asked to set up a free personal account. Every time you go back to TLG, you will need to log in again, using the login screen at the top right of the initial TLG page.
There is no translation included with TLG. 

Loeb Classical Library - Electronic texts of Greek and Latin authors, with English translations on opposing pages.  This is the entire collection

Many Loeb volumes are public domain and thus available in open access full text. Links to available volumes - Listed in series number order. (In most cases, the "Archive" link is more reliable than the "Google" link.)  Wikipedia Index to Loeb volumes by author.

• Library of Ancient Texts Online
  Greek texts 
• Internet Classics Archive 
  Greek and Roman authors in English Translation.
• Corpus Scriptorum Latinorum
  ​Latin texts 
• Monastica 
  "Monastica is an open access digital platform for research on the transmission of the so called Sayings of the Desert Fathers, known in Greek as the Apophthegmata Patrum and in Latin as the Verba Seniorum, as well as closely related early monastic literature. It is a dynamic library of texts as well as a complex relational database and advanced tools for scholarly collaboration in gathering, analysing, visualizing, publishing and sharing the complex fluid textual tradition of the Sayings of the Desert Fathers in multiple languages."

• Milligan, Selections from the Greek Papyri with Translations and Notes (1912)
• Oxyrhynchus Papyri vols. 1-14
• Oxyrhynchus Papyri Vol. 15
  Further volumes are avalable through Internet Archive: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 26, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75,76, 77, 78, 79, 80, 81, 82, 83 (volumes without links are not available full text)

Index Thomisticus - A searchable index to all the works of Thomas Aquinas in Latin