I apologize for a question that is not about mathematics, but I believe it is of interest to research mathematicians, and I believe there may be people on MathOverflow who can answer it objectively. If it is deemed unacceptable, I can survive.
For many years, I (and many others I know) have used a ranking of mathematics journals produced by the Australian Mathematical Society in 2009, formerly found here https://austms.org.au/Rankings/AustMS_final_ranked.html.
Without wishing to get into a debate on the usefulness or methodology of ranking journals, I found the list useful for judging what journals to submit papers to, and for justifying to deans or hiring committees the quality of journals that I or others (e.g. job, tenure applicants) have published in. I understand that it was getting out of date and I certainly did not agree with every grade there. But since it was made by mathematicians, rather than some trite formula, and since it used a simple A*/A/B/C grading scheme, it was solid and easy to reference and cite. For example, I planned to use it to help justify to deans an upcoming tenure decision.
It was also the top rated answer to this MO question about journal rankings. Unfortunately, the link above is now dead.
Question 1: Does anyone know if this ranking is permanently gone from the internet? If the society has "disavowed" it as incorrect or out of date? If they are revising it? Or if the link has simply changed?
I was able to find a "cached" version, so I still have access to the information. But I do not know how long this will be up, and it detracts from any semblance of authority if it is no longer hosted on a reputable website.
If this list is gone forever,
Question 2: Do people have suggestions for a replacement with similar features? (Made by a reputable institution, with input from mathematicians rather than a trite formula, and easy to explain to non-mathematicians.)
I understand that the second question has some overlap with the prior MO question linked above.
Best Answer
There are several sources online that rank math journals by impact factor (and, this comes from a professor's webpage) or journal citation reports. However, it is important to realize that impact factor is a highly unstable metric, as discussed here.
Thomson Reuters has a list ranking by JCR, which appears to now be behind a paywall called InCites (though you might be able to access it through your library). If I remember correctly there was also an option to rank by impact factor.
The Institute for Scientific Information (ISI) is another source that maintains a database. And there's Scimago mentioned by Yemon. And you can look up impact factors over the years at bioxbio.com.
Another ranking by impact factor was SciJournal.org, but their website also appears to be down. A general way to solve the issue of disappearing website is the WayBack machine. For SciJournal, here is a recent snapshot from 2020. For the Australian list, here is a July, 2020 snapshot. In the same spirit as the Australian list, I am aware of a Chilean list that breaks journals into categories such as "Muy Buena," "Buena," and "aceptable" (I'm not sure if this is actually the third category). I've heard that this breakdown is not super well-regarded.
Lastly, an alternative to impact factor, that I've read about but have not yet looked into, is scite.