We have customized a few existing tools to suit our testing and production. Maybe they will also be useful for you as well.
Devanagari Type Design Resource Listing: Our list of recommended books, websites, and tools useful for Devanagari type design.
Lists of words useful for testing type: Random and fun, we’ve made these collections over the years to be used to evaluate your type.
Kern-On: A sweet new kerning helping plugin for Glyphs
RMX Tools: Invaluable plugins for Glyphs that help scale and fine-tune your characters. I’ve saved days or weeks of work thanks to these plugins!
JAF Text Generator: Simple but handy website to generate sample text to proof fonts
Wakamaifondue: Website to test out your variable fonts
Alphabet’s Tools: Alphabet (the company) offers several tools especially useful in helping to define character sets and test for language support.
Hyperglot: Made by Rosetta, this tool might just be the definitive source for checking for language support.
Type Drawers: Not a tool, but an active forum of discussions about anything type-related.