This is live pricing from Travelpayouts' aggregation of 40+ booking engines. The $413 fare is the cheapest current round-trip from San Francisco (SFO) to BOS on Southwest flight WN257, departing 2026-08-01 at 20:05 with return on 2026-08-08.

Clicking "Book this flight" opens Kiwi.com with this exact flight pre-filtered — same airline, same dates, same passenger count.