Often our best critical editions for patristic sources are from the venerable Sources Chrétiennes series (SC), a mainstay for anyone working on early Christian studies, ancient theology, and ancient philosophy. The Loeb Classical Library (LCL) went online years ago, and Brepols brings us SC Online. It will include searchable, online editions with French translations not only of Greek and Latin sources, but sources in Syriac, Aramaic, and Georgian.
While TLG or LCL online do permit (very) limited browsing without a subscription, SC does not appear to be there (yet). A subscription will be required to use the resource, and prices are targeted towards institutions. More information can be found at Brepols’ site for the resource here. For a list of the 200 titles that are available online at launch, see here.