Where to find real market gaps — RFS lists, review mining, and problems people already pay to avoid

The frame A market gap is a problem people already work around badly — with a spreadsheet, a manual process, three tools taped together, or by just putting up with it. You are not looking for something nobody has thought of. You are looking for something enough people hate enough to pay to stop doing. The trap is inventing a gap from your armchair. "Nobody has built this" is usually either false, or true for a reason you haven't found yet. A real gap has people on the other side of it you can name and talk to this week. Where gaps are written down for you · Y Combinator — Requests for Startups. A published list of problems YC actively wants funded, with the reasoning behind each. Not a to-do list — a map of where experienced investors think the openings are. · Y Combinator Startup Library. Talks and essays, several of them specifically on finding and judging ideas. · "How to Get Startup Ideas" by Paul Graham. The one essay to read first. "Live in the future, then build what's missing" and "make something you yourself want" both come from here. · r/SomebodyMakeThis and subreddits like it. People posting the thing they wish existed, unprompted. Noisy one post at a time; the pattern across fifty is signal. Where gaps hide in plain sight · One- and two-star reviews of the incumbent — G2, Capterra, the App Store, Amazon. People tell you exactly what is missing and how angry it makes them, for free. · Support forums and community Slacks for tools you already use. The question asked every week whose answer is always "you can't do that yet" or "here's a workaround". · Your own last month. The tasks you dreaded, the tool you rage-quit, the spreadsheet you rebuilt for the third time. · A friend's industry you don't work in. Ask what the most annoying part of their week is, and why the software they were handed doesn't fix it. The test for whether a gap is real Get to five people who have the problem now — not "would find it interesting", have it now — and ask what they do about it today. If the honest answer is "nothing, it's not that bad", the gap isn't real yet. If they show you the ugly workaround they built themselves, you have found something. Then write one sentence each for: who has this, what it costs them today, and why now. If you can't fill all three in, keep looking.