Slightly facetiously, I'm mildly tempted to vote to close as a duplicate. However, I shan't and shall merely point out that most of the answers to the question: Is a free alternative to MathSciNet possible?Is a free alternative to MathSciNet possible? are relevant to this question, particularly mine. The question Errata database?Errata database? which covers similar ground.
(The rForum mentioned in the latter has stalled a little. It could be revived if sufficient interest is shown.)
