Short answer — there’s no single universal database, but you can compare award availability using a mix of specialist aggregators, alliance/airline tools, calendar search sites, and expert services. Use aggregators to find options quickly, then always verify and book on the airline or partner site. Useful places to check:

Aggregators / paid services

• ExpertFlyer — award and upgrade search, alerts, good for many carriers (paid subscription).
• Point.Me (formerly Juicy Miles) — searches award availability and builds itineraries across programs (paid).
• AwardWallet — tracks balances and can show some availability and alerts (free + paid features).
• SeatSpy — strong for UK/European carriers (e.g., BA) and specific routes (subscription).
• KVS Tool — award/upgrade availability search for certain alliances (paid).

Free tools / comparison helpers

• AwardHacker — shows which programs/routes commonly require how many miles (good for planning but doesn’t show live availability).
• Airline alliance calendars and multi-search pages — e.g., ANA, United, Aeroplan, and British Airways sites let you search partner award seats (useful to compare how different programs see the same flight).
• Individual airline websites — many show partner award availability if you search directly (e.g., United.com, Aeroplan, Avianca LifeMiles, Alaska, etc.). Searching the same date on several airline sites often reveals which program has access.

Forums / community tools

• FlyerTalk and Reddit (r/awardtravel) — users share tips, tricks, and real-time availability finds.
• Dedicated blogs and seat-finding posts often point to less-known program quirks.

Travel agents and concierge services

• Award booking services / specialist agents — they search multiple programs and can book complex itineraries for a fee (useful if you don’t want to spend time hunting or if availability is fragmented).

Practical tips

• Search the same flight on multiple programs — partner inventory can show up for some programs but not others.
• Use flexible dates and calendars — weeks/month view helps spot availability.
• Set alerts where available (ExpertFlyer, SeatSpy, AwardWallet) because award inventory changes rapidly.
• Be ready to verify and book immediately — holds rarely last long; price and seat can disappear.
• Remember blackout rules, carrier-imposed surcharges, and differing partner routing rules can change the “best” option beyond just mileage cost.

If you want, tell me the route, dates (or flexible window), and which points currencies you have and I can suggest the best specific places to search and a step-by-step plan for finding seats.