I have a very specific set of criteria for a font I need, and wondered if there was any online tool that would allow me to choose the specific anatomy of different characters and show me a font that matches? For example, a sans serif font with a single storey lower-case "a", a lower-case "t" with a tail, a closed "4", a lower case "g" with an open loop, an upper case "J" with a top bar..etc. I have tried the "Identify fonts by sight" question tool on fonts.com, but it doesn't ask me questions about the characters I'm especially interested in. Is there any tool in existence that does what I need?! I should add that I'm not looking to identify a font I've seen - I simply need a font that matches my criteria and would like to know what my options are. Many thanks!
Try Identifont and then pick "don't know" to the characters you don't care about?
Identifont is a tool used to identify fonts with questions about specific characters, exactly the things you name.