ShovelScout

ShovelScout finds the public posts where people are already asking for something like what you sell. You type a phrase, say "invoice automation", and it goes through Reddit, Hacker News and a few business forums looking for the sentences where someone asks for a product, a recommendation, or an alternative to what they use now. Each result links back to the original thread, so you can read the conversation and answer there yourself instead of sending a cold message. Unlike a keyword search, you get the source link on every hit, so nothing is invented and you can check it yourself. You also get the writer's exact wording, handy for copy and positioning. It is free to search and needs no account. Only public posts are readable, so private groups and paid communities are out of reach.

Founders, indie developers, agencies and consultants who answer questions in public communities to find their next customers.

Most tools tell you that a keyword showed up somewhere. That still leaves you reading hundreds of threads to work out which ones are actually people asking for something. ShovelScout labels each result with what the poster wants, so you can skip the ones that are just discussion and open the ones that are a real question.