I was looking today for some quick timeline information on OT authorship, so I pulled up the Old Testament Books Timeline tool for the first time. I must say, I was quite disappointed with what I found. The three sources used in the Timeline tool all placed Job as the first book written in the Bible—two of them placed it as early as 2100 BC!
Now, this isn't an utterly unheard of viewpoint. But it's certainly not the consensus of modern critical scholars. David Clines in the Word Biblical Commentary (certainly not a bastion of liberalism) says this of Job's dating:
"Most scholars today would date the composition of the Book of Job to some point between the seventh and the second centuries b.c.e., with the probability that a prose folktale of a pious sufferer existed long before the largely poetic book itself was written."
Once I saw that I pretty much gave up on getting much out of the tool. I'm not arguing that these sources with older dating should be excluded, but at least one source that reflects the more modern critical consensus should be included. To leave that out creates the misleading impression that the dates given are widely agreed upon.
I have to say that the NT Books Timeline is considerably better. The majority of sources are older, and demonstrated by the fact that most of them put Matthew as the first Gospel written, but there are at least a few sources that lay out a timeline with Markan priority (Robinson and Peterson).
One feature that might alleviate some of the tendency of these tools to present a misleading level of certainty would be a link to the source. Each of these dates has to be pulled from a particular page in the source material—to be able to read the author's reasoning and cautions would be quite helpful.