Crossref [Link]
Crossref makes research outputs easy to find, cite, link, assess, and reuse. We’re a not-for-profit membership organization that exists to make scholarly communications better. We rally the community; tag and share metadata; run an open infrastructure; play with technology; and make tools and services—all to help put scholarly content in context.

Directory of Research Journals Indexing [Link]
DRJI provides ready access to education literature to support the use of educational research and information to improve practice in learning, teaching, educational decision-making, and research. Directory of Research Journals Indexing is a free online service that helps you to find web resources for your articles and research.

Eurasian Scientific Journal Index [Link]
The ESJI provides indexing of major international journals and proceedings. Author can get information about international journal impact factor, proceedings (research papers) and information on upcoming events. All the journal pages have pointers to Web pages of the publishers which are integrated into the ESJI stream pages.

Index Copernicus World List [Link]
The growing interest in the ICI Journals Master List database, the number of applications and the number of journals which had not met the criteria required for the indexation, have inspired us to create a global database of scientific journals the ICI World of Journals. 

Scilit [Link]
Scilit is a comprehensive, free database for scientists using a new method to collate data and indexing scientific material. Our crawlers extract the latest data from CrossRef and PubMed on a daily basis. This means that newly published articles are added to Scilit immediately.