Stripe, one of the world’s most valuable startups, may leave San Francisco.

The payments processing company, valued at $35 billion, is considering moving about 10 miles away to South San Francisco, said two people familiar with the company’s potential plans. The company is currently headquartered at 510 Townsend St. in South of Market.

The primary reason for the potential move is San Francisco’s lack of available office space, said one person, who wasn’t authorized to speak publicly. The city’s downtown vacancy rate is below 5%, and there are few options for growth.

“We don’t have any specific plans to announce, nor do we comment on speculation,” said Mike Manning, a Stripe spokesman. “But we’re always considering how best to expand Stripe’s presence across our global offices. The lack of available commercial real estate in San Francisco is a serious challenge for companies of all sizes, and Stripe is no exception.”

Stripe is considering a lease for part of developer Kilroy Realty’s Oyster Point project, a waterfront campus under construction totaling 2.5 million square feet, the people said. The area has historically been a biotech hub and is next to Genentech’s headquarters. Earlier this year, muscle treatment maker Cytokinetics Inc. signed a lease for 234,892 square feet at Oyster Point.

If it moves, Stripe would be one of the city’s largest corporate departures. A recent exodus is mostly affecting older firms outside the tech industry, such as McKesson and Bechtel. San Francisco tech companies have generally expanded across the Bay Area and country while keeping their headquarters in San Francisco.

In 2011, Twitter threatened to move to Brisbane. Instead, it moved to San Francisco’s Mid-Market after the city passed a payroll tax exemption in the area.

Stripe has 2,000 employees worldwide, and about half of them work in San Francisco. The company leases 300,000 square feet at 510 Townsend St.

Stripe’s potential move reflects San Francisco’s restrictions on office space pushing companies to look elsewhere, said Alicia John-Baptiste, CEO of urban-planning think tank SPUR. The city’s 1986 law Proposition M limits the amount of office space that can be approved each year, and a recent rezoning that would allow more offices in Central South of Market led to multiple lawsuits from opponents.

“We’re in a moment where there’s demand that literally can’t be met,” she said. “We’re limiting choices,” John-Baptiste said.

The move could also worsen commutes for Stripe workers, because public transit isn’t as robust compared with San Francisco, John-Baptiste said. While South San Francisco is served by Caltrain and BART, those stations are relatively far away from Oyster Point.

“It’s very challenging to provide sustainable transportation options in that part of the region,” she said.

Stripe builds software that allows customers to send payments to businesses, and its clients include tech giants Google, Microsoft and Uber. Stripe has raised about $1.2 billion and now has a higher valuation than Airbnb and Palantir.

Stripe also opposed November’s Proposition C, which raised taxes for San Francisco companies making more than $50 million in gross receipts a year.

CEO Patrick Collison wrote in October that Stripe was “happy to pay higher taxes” to help solve homelessness, but Prop. C wouldn’t be effective because the issue requires city policy changes.

Jon Zieger, Stripe’s general counsel, wrote on Medium that the measure would hurt “retailers, manufacturers and others who have low profit margins, many of which are already struggling as the economy transforms. It will hurt companies like Stripe, too.”

The measure passed with around 60% of voters in support. It isn’t clear whether Prop. C is a significant factor as Stripe considers a move.

Jack Dorsey, CEO of Square and Twitter, said last year Prop. C would disproportionately affect tech companies focused on financial transactions.

“Companies like Square and Stripe would be taxed at a significantly larger total contribution than much larger companies like Salesforce,” Dorsey wrote on Twitter in October.

Roland Li is a Chronicle staff writer. Email: roland.li@sfchronicle.com Twitter: @rolandlisf