The menu at the top of the previewer in the HTML 5 version of eFileCabinet Online on https://app.efilecabinet.com/#/main provides you with a number of options to make specific modifications to documents, all without requiring you to check the document out of EFCO.

Search
The search function allows you to search for text contained within a document

Note: when it comes to image files like pdfs, the files will have to have been properly indexed/processed through a pdf editor's OCR engine in order for that text to be searchable via the previewer in EFCO)

Annotate
The annotate function allows you to add different annotations (text boxes, approval stamps, etc) to your documents in EFCO.

Redact
The redact function allows you to redact specific information within a document (or even entire pages).

E-Sign
The e-sign function allows you to place your signature on a document straight from the previewer (no additional third party electronic signature software needed)

Form Template
The form template function allows you to set up specific requirements on a document that need be performed (for example, setting up a signature space allows you to leave a space for another user to apply a signature to).