One Friday in March, several hundred volunteers filed into the headquarters of GitHub, in South Beach, San Francisco. The space looked like a warehouse turned into a rec center for an exceptionally wealthy university—aged-leather couches, wagon-wheel chandeliers suspended over long raw-wood tables, a snack station with candy dispensers, young people playing Ping-Pong, foosball, and pool. In the wide-open main room, an orange shipping container made a visual pun on the work that GitHub does: “shipping code.” As the volunteers arrived, they were issued neon-green wristbands and blank name tags on which they could write their pronouns and professions—“E” for engineer, “D” for designer, “P” for press. You could add a purple heart sticker if you had training as a listener, or an orange circle if you preferred not to be photographed. New arrivals clustered near the refrigerators, which were stocked with beers and LaCroix sparkling water, and made tentative conversation.

“You’re from data viz, right?”

A nod.

“I recognize you from the Slack.”

A woman asked the organizers whether a friend could join. “She’s a dev-ops engineer!”

Did the friend have photo I.D. on her?

She did not.

The organizers politely declined. They had spent weeks vetting the crowd, asking questions of some six hundred and forty applicants in hopes of screening out anyone who might make others feel unsafe. The few hundred engineers and activists who had ultimately shown up, most of them women, would be spending the weekend coming up with tech-enabled ways to improve access to abortion.

At eight P.M., Kate Bertash, the thirty-year-old startup employee who had spearheaded the hackathon, took to the stage, wearing a bright-red skirt and a black T-shirt that read “RESIST.” She welcomed everyone and stressed that the goal of the weekend was “collaboration, not competition.” At eight-thirty, spokespeople for the teams that had been forming in the hackathon’s Slack channel lined up to make thirty-second pitches for their projects. One team planned to create an online fund-raising tool for women seeking abortions. Another proposed building an anonymous social network, since women who share abortion stories on Facebook are often bullied. Other teams would make smartphone apps that could tell a woman her options based on her age, weeks into pregnancy, and Zip code. They would design bots to search government sites, using keywords to pull and parse new legislation that might affect access. The event materials used the language of reproductive justice, calling for prenatal care, healthy food, clean water, and child care for women who want to become mothers—as well as abortion for women who do not. Still, the organizers expected pushback. “We got our first bloody fetus on the hashtag!” the social-media manager, Andrea Grimes, exclaimed around nine P.M. “We didn’t even do much publicity.”

Opponents of abortion have contested Roe v. Wade more or less continuously since the case was decided, in 1973, but the fundamental right to privacy on which Justice Harry Blackmun based his ruling has proved resilient. In the past few decades, rather than challenging that legal principle, opponents have focussed on making abortion more difficult to obtain. At the state level, they have been remarkably successful in passing legislation that restricts abortion coverage to private insurance plans, that requires repeated visits to the clinic, that mandates counselling sessions on a fetus’s capacity to feel pain. Sixty per cent of women who seek abortions in America have children already; seventy-five per cent live near or below the poverty line. For those who cannot afford to lose wages, or to pay for lodging and child care, in addition to the procedure itself, these obstacles often prove insurmountable.

The aim of the hackathon was to respond with what Grimes called “subversions and workarounds.” The event at GitHub was not the first attempt. In September, three volunteers put together an Abortion Access Hackathon at the University of California, Davis. Between twenty and thirty people attended. Emily Loen, one of the organizers, had tried to invite a Google-affiliated developers’ group to participate, but the group said no because, one member wrote, the subject was too “politically biased.” (A Google spokesman declined to comment.) For the San Francisco iteration, the organizers agreed to focus their efforts on abortion funds—grassroots organizations that offer women financial and logistical support. Though smaller and less well-known than Planned Parenthood, the National Network of Abortion Funds connects patients with the sorts of local clinics that still perform the majority of abortions in the United States. Bertash, who had been raising money for abortion funds in her home state of Texas, read about the U.C. Davis event, e-mailed Loen, and asked for her help replicating it. “It’s not that these are complex and unknown problems,” Bertash told me. “Other industries have come up with a host of solutions, where it is lucrative to solve them. If this were about finding a Crossfit class, someone would have set up the script.” Shireen Whitaker, a masters student who coörganized the Davis event, added, “It makes sense that San Francisco would take it and make it a thousand times bigger.”

The tech industry is not known for attending to the needs of women. But the Abortion Access Hackathon did appeal to a core industry belief—that even the most intractable problems can be solved if only you break them down into the right set of engineering decisions. As the weekend wore on, the hackers eased into their designated spaces and rhythms. The team making Vettit, a program to automate the process of screening clinic volunteers by aggregating and scanning their social media, set up near the entrance. Whitaker was thrilled. “Right now, I spend all my time researching antis,” she said—abortion opponents who attempt to infiltrate clinics undercover. On a sofa across the room, volunteers with Access Women’s Health Justice were trying to connect Twilio, a communications platform, with Geopointe, a data-mapping tool. Geopointe would identify volunteers who might be able to help with a need somewhere—giving a woman a ride to a clinic, say, or watching her children—and Twilio would send them a text. At one of the busiest tables, Colin Fleming, a volunteer from the D.C. Abortion Fund, was managing a large team of Ruby on Rails developers. Fleming said that he had travelled from Washington to San Francisco for the hackathon because DCAF (pronounced “decaf”) desperately needed better Web apps. Until recently, the organization’s C.M.s—case managers—had relied on a clunky Excel spreadsheet. “This is going to make C.M.s’ lives so much easier,” he effused.

In some ways, the weekend at GitHub recalled older feminist gatherings. Many participants were recent graduates of get-girls-to-code boot camps; many brought children. A stroller stood parked next to one of the cafeteria tables, its drowsy inhabitant attracting passersby; two small boys in giant Giants caps clambered on the shipping container; a gangly eleven-year-old lounged on a sofa in blue headphones, watching something on her iPad. “There have always been networks of women who share the knowledge they need,” Loen told me. Abortion was not criminalized in the United States until the eighteen-sixties. In many times and places—as far back as ancient Rome—it was assumed that nurses and midwives could help end unwanted pregnancies. If women once gathered to pass around herbs and vines and illegal diaphragms and D.I.Y. abortion kits, why not code?

The organizers were talking about repeating the hackathon in New York, Los Angeles, and Austin. They spoke with the can-do optimism that is characteristic of the tech industry, but their conversations were tempered with a quiet acknowledgement of the new reality: already, the Trump Administration has emboldened opponents of reproductive choice. Last fall, on the campaign trail, Trump pledged to appoint Supreme Court justices who would overturn Roe v. Wade. In his first week in the Oval Office, he signed an executive order that bars the federal government from funding international organizations that so much as provide information on abortion. State legislators, meanwhile, have lately introduced bills to criminalize abortion starting as early as six weeks, to require women to provide written permission from the fetus’s father, to mandate the burial of fetal remains, and to allow doctors to withhold genetic-test results if they think that the truth might lead a patient to end her pregnancy. The attitudes driving these policies cannot be programmed away.