Here are the best sites and tools for finding and booking award flights, grouped by purpose so you can pick the right tool for each step (search, monitor, or have someone book for you):

Top search & availability tools

• ExpertFlyer — paid, powerful award/upgrade availability searches and alerts (works well for many airlines and for spotting partner inventory). Good if you want fine-grain control and flight alerts. (expertflyer.com)
• Seats.aero — fast, modern award-search engine that searches many programs and provides alerts and booking instructions (free tier + Pro). Great for broad, quick searches and monitoring. (docs.seats.aero)
• SeatSpy — specialty tool for checking British Airways/Avios reward availability with calendar view and alerts (excellent if you use Avios). (seatspy.com)
• AwardHacker — free, simple tool to show which frequent‑flyer programs typically offer the lowest-mileage redemptions for a route; good for planning where to transfer points (note: it doesn’t show live inventory). (awardhacker.com)

Concierge / paid booking services (they search + book for you)

• Juicy Miles (also known as JuicyMiles) and similar “award-booking” services — they’ll search options across programs and can complete bookings for a fee (handy when itineraries are complex or you don’t want to deal with partner calls). Useful if you value time over the service fee. (cntraveler.com)

Tracking & organization tools

• AwardWallet — tracks balances, expirations and reservations across many programs (useful to avoid losing miles), though programs sometimes limit automatic tracking so expect occasional manual work or gaps.

Other useful notes and real‑world tips

• Always search both the airline’s own website and partner programs. Some partner sites show award space that the carrier’s site does not, and availability can vary by program. Tools above help surface possibilities, but final booking is often best done on the program that has the seats you want.
• Tools that aggregate award availability can be imperfect or stale (cache limits, API restrictions) — if a tool shows availability, verify immediately on the airline/program site or by calling the program.
• Use alerts (ExpertFlyer, Seats.aero, SeatSpy) for high-demand routes and premium cabins — new seats are released irregularly.
• If you’re stuck or booking a complicated multi‑partner itinerary, using a paid award-booking agent can save time and sometimes money versus trying to stitch routes yourself.
• Compare several tools — each has different coverage and quirks; using 2–3 in parallel increases chances of finding the right award.

If you want, tell me: which origin/destination, dates (or flexible?), cabin class, and what miles/points you have — I can suggest which tools to check first and a step‑by‑step search plan.