toolkit, toolbox

(They are not in Longman dictionary)

• toolkit [n] a set of software applications that aid a task; also written "tool kit", also called toolset.
• toolbox [n] a box or case in which tools are kept.

[source: dictionary.reference.com]

According that toolkit means group of tools, so it needn't be plural forms (toolkits does not mean many tools but many sets of tools).