I’ve linked in the past to Indentifont, which asks you a series of questions about a font to help identify it.
But I only just found out that there are several services that can identify a font based on an image of characters from the font.
- WhatTheFont, from MyFonts. Finds matches among their fonts. Also available as a mobile app.
- Find my Font. Not limited to MyFonts fonts, but the desktop version does cost money (after a free trial period). But they too have a mobile app, which appears to be free.
- Font Moose. Beta software, limited to MyFonts fonts, and in my one attempt to use it so far, it didn’t correctly identify the font. But it did give me some interestingly similar fonts.