Short answer — several third‑party award‑search engines let you check award availability across many airlines/programs at once. The most-used options are:

• Seats.aero — searches award availability across dozens of airline loyalty programs and lets you compare results from multiple programs in one place (free + Pro tiers). (seats.aero.)
• Point.me — paid service that searches 30+ airline programs / 100+ airlines and shows which transferable points can book each result. Good for beginners. (upgradedpoints.com)
• ExpertFlyer — long‑running tool that can display award & upgrade inventory for many airlines (subscription required); supports alerts. (expertflyer.com)
• AwardTool — commercial award search that lets you query many programs/dates and set alerts (Pro features for wider coverage). (frequentmiler.com)
• PointsYeah — newer tool with multi‑program searches (free + paid tiers) and date/explore features. (nerdwallet.com)
• Roame (roame.travel) — app/web tool that searches many airline loyalty programs (free tier + paid SkyView) and supports region/countrywide searches and alerts. (help.roame.travel)
• SeatSpy — focused on a set of airlines (British Airways, KLM/Air France, United, American, Virgin Atlantic, etc.) but shows long‑range calendars and alerts across those carriers. (seatspy.com)
• Points Path (browser extension) — injects award prices from multiple programs into Google Flights searches (free + Pro with extra programs). (pointspath.com)
• AwardFares / AwardTravelFinder / Roame and other smaller engines — several niche tools also exist that aggregate multiple programs (coverage and reliability vary). (awardfares.com)

Important caveats (read before you rely on results):

• Coverage varies by tool — no single tool covers every airline or every loyalty program. Check each tool’s “supported programs” list for the routes/programs you care about. (docs.seats.aero)
• Award inventory is dynamic and some tools show “phantom” or delayed inventory; always confirm availability on the airline/program website (or call the program) before transferring points. (wsj.com)

If you want, tell me the route(s) and program(s) you care about and I’ll say which of these tools is most likely to show good results for that specific search.