Background. Elsevier relies on the peer review process to uphold the quality and validity of individual articles and the journals that publish them. ... Despite many criticisms about the integrity of peer review, the majority of the research community still believes peer review is the best form of scientific evaluation.

Are all Elsevier journals peer reviewed?

All articles in open access journals which are published by Elsevier have undergone peer review and upon acceptance are immediately and permanently free for everyone to read and download.

Is Elsevier credible?

They're generally legitimate. The negative reviews and boycotts aren't about the quality of the journal, but are because of Elsevier's alleged high prices (see The Cost of Knowledge). Elsevier publishes some of the best journals in some fields, e.g. The Lancet and Cell.