The official website for the United Nations. Pre-set to English but can be changed into other languages. Includes documents, a treaty collection, research guides, yearbooks of the United Nations, news, and more!
The United Nations Digital Library includes UN documents, voting data, speeches, maps, and open access publications. The platform provides access to UN-produced materials in digital format and bibliographic records for print UN documents starting in 1979. System features include linked data between related documentation such as resolutions, meeting records and voting, and refining of searches by UN body, agency or type of document. [Taken from UN website]
For researchign international law: "The International Law Commission was established by the General Assembly, in 1947, to undertake the mandate of the Assembly, under article 13 (1) (a) of the Charter of the United Nations to "initiate studies and make recommendations for the purpose of ... encouraging the progressive development of international law and its codification"." [Taken from International Law Commission website]