SwingVision app gives tennis players from amateurs to pros a rare commodity: Data

By Joe Lemire, SportTechie
James Blake and Andy Roddick are among those who have invested in the technology.getty images

Swupnil Sahai and Richard Hsu were high school tennis players who became roommates at UC Berkeley a decade ago. They bonded over the sport before each pursued careers in STEM. Hsu earned a master’s in computer science at Stanford before working at LinkedIn and then at an AI-based software startup acquired by Cisco. Sahai, meanwhile, earned a doctorate in statistics from Columbia and then worked at Tesla in its autonomous driving division.


Those complementary careers in tech — and their unifying love of tennis — reunited Sahai and Hsu on their own startup, SwingVision, which uses a single iPhone or iPad camera to track shots, tag and clip videos, and provide automated line calls.

The product, graduated from Techstars SportsTech Melbourne Accelerator, has been featured in multiple Apple keynotes and commercials, and became the official ball-tracking app of three major organizations — the Intercollegiate Tennis Association, Tennis Australia and the U.K.’s Lawn Tennis Association. SwingVision also closed a $2 million seed round led by Tennis Australia that includes backing from retired stars James Blake and Andy Roddick, as well as MyFitnessPal co-founders Albert and Mike Lee, and former Strava and current Homebase CFO Jason Liu.

At Tesla, Sahai worked on tracking objects from a single camera, even filing some patents related to that technology.

“That’s where the spark came because I was working on all these algorithms to track pedestrians and vehicles around the car using the camera,” Sahai said, “and so I was thinking, ‘Well, why can’t they use something like that to track the tennis ball?’ And there was basically nothing out there to do that at the consumer level.”

Hawk-Eye has proved itself as a line-calling arbiter at the Grand Slam level, but its enterprise system is too costly for even some pro tournaments. PlaySight is more affordable for tennis clubs and college programs, but isn’t accessible by lower tiers — including the millions of amateur players.

SwingVision, which typically costs $149.99 per year, succeeds because of its simplicity. A player simply needs to hang an iOS device behind the baseline, at least five feet in the air, and press record. The app can provide data such as shot speed, location tendencies and an accuracy score for forehands, backhands and serves. It can measure a shot’s proximity to the baseline and sidelines and calculate a player’s distance run during a match.


One popular feature, Sahai said, is the edited playback of a match. The time spent retrieving balls and drinking water is removed, and a two-hour match can be condensed to 20 minutes. Players can also filter highlights automatically, such as “all rallies of at least five shots.”

SwingVision is the first investment for Tennis Australia’s newly launched Wildcard Ventures fund and follows a prior agreement to distribute the app to association coaches. Tennis Australia’s head of innovation, Machar Reid, said players at all levels — from “young kids through to Ash Barty,” the women’s world No. 1 — can benefit. Even the pros, for instance, suffer from a real lack of information and analytics not only when training but also during competitions.

“Something James told me,” Sahai said of Blake, a former world No. 4, “which surprised me but makes sense, is [that] outside of the matches that they play on center court, they have no data at all.”

Those wearing an Apple Watch have access to additional features such as a wrist-worn line challenge, needing only a single tap to be shown a slow-motion replay zoomed in on the ball.

“For the really close calls, this is already more accurate than the players because the phone’s recording at 60 frames per second,” said Sahai, who serves as CEO with Hsu as CTO. “Typically, humans see at about 24 frames per second. So, it’s seeing at a better fidelity than a human can.”

Sahai admits that the app isn’t consistently accurate enough to replicate Hawk-Eye Live’s real-time line calling for tournaments but expects to be there next year. He says professional line judges average 92% accuracy on shots that land within 10 centimeters of a boundary line, so the goal is to surpass that benchmark while also logging near-100% accuracy on all other shots. A live scoring app — with an automated umpire announcing each point — is also in the works to deliver “that Grand Slam experience” to all players, Sahai said.

“It’s something that PlaySight tried to tackle in a really infrastructure-laden way, but if you’re able to do it through a means that’s more scalable, we’re like, holy heck, you’re addressing a real problem for the sport,” Reid said.

The addition of Roddick and Blake as investors was, in part, fortuitous. Sahai played high school tennis with John Lamble, who later played on the ATP Tour and worked with Dr. David Clarke, who developed CrampsAway — which used Blake as the face of the product. Blake invested first, then introduced the SwingVision team to Roddick at an exhibition match in Texas.

Roddick was duly impressed with the app and, Sahai said, also grateful for help finding his phone before he had to catch a flight. Blake tried calling Roddick, but the phone was silenced — at which point Sahai introduced him to the “Find my iPhone” feature.

Upon retrieving his device, Roddick jokingly offered a five-figure Venmo payment on the spot.

For more reporting and analysis at the intersection of sports and technology go to

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