Budget airlines flying from SFO to Denver offer affordable travel options between San Francisco and Denver. These airlines prioritize cost-effective services, making them a popular choice for travelers looking to save on flights from SFO to Denver. While amenities may be more basic compared to premium carriers, passengers can expect competitive fares, flexible booking options, and convenient flight times, making it an excellent choice for budget-conscious travelers. Popular budget airlines on this route include Southwest, Spirit, and Frontier.