The 11 best startups from Y Combinator’s S19 Demo Day 1

tY Combinator, the genesis for many of the companies that have shaped Silicon Valley including Airbnb, PagerDuty and Stripe, has minted another 200 some graduates. Half of those companies made their pitch to investors today during Day 1 of Y Combinator’s Summer 2019 Demo Day event and we’re here to tell you which startups are on the fast-track to the unicorn club.

Eighty-four startups presented (read the full run-through of every company plus some early analysis here) and after chatting with investors, batch founders and of course, debating amongst ourselves, we’ve nailed down the 11 most promising startups to present during Day 1. We’ll be back Tuesday with our second round of top picks.

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Compound provides wealth management for startup employees, helping them figure out what their stock options actually mean, forecast their value over time and optimize against things like potential taxes. Launched two weeks ago, they currently have 200 startup employees as customers.

Young tech workers and startup employees are at the beginning of their financial independence. New grads often aren’t equipped with the best savings and financial planning strategies right off the bat. Compound is jumping on the opportunity to start a financial relationship with soon-to-be-rich customers who are already accruing equity at high-growth startups.

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PopSQL provides collaborative SQL query editing. You can store SQL queries you run regularly, grouping them into folders that can be kept private or shared amongst your team. Version history tracks changes so it can be reverted if/when something breaks. It currently has more than 100 paying companies, and is making $13K per month. It plans to build a marketplace for apps that run on top of your company’s database.

SQL database queries can be a nightmare, especially if they’re not something you’re used to dealing with every day. PopSQL lets you hammer on queries collaboratively until they’re working exactly as you want — then you can save them for future use and share them amongst your team members. And when you’ve spent the last 45 minutes trying to figure out why your query isn’t working only for a team mate to fix it in thirty seconds, you can use version control to see exactly what they changed. PopSQL says its product has already found customers in companies like Instacart, Redfin, and DoorDash.

demoday LEGACY


Legacy is a male fertility startup building a mail-in sperm testing product that helps people test their reproductive health without leaving their home. The company sells a kit that users can use and send back to them, at which point Legacy is able to analyze the sperm and let users know whether everything is in good working order.

Legacy has already raised some money – $1.5 million to be exact. The company’s long-term goal is to leverage its growing collection of data, which is end-to-end encrypted and HIPAA-compliant, to become a research center for male fertility. That, the founders admit, will take many years and more capital (they are expecting to begin fundraising again very soon), but they aren’t in a rush. Read more about Legacy’s story here. 

As tech startups enter the fertility sector in drovers, Legacy presents an interesting opportunity to bring awareness to male fertility issues. Though it’s up against competition, including another venture-backed male sperm storage company, Dadi, it’s poised to take control of the market thanks to its well-versed and highly credible team.

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Rent the Backyard

Imagine building and then renting out a studio apartment in your own backyard. Well, that’s what Rent the Backyard is all about. Rent the Backyard handles everything from the construction of the studio to selecting the tenant to occupy it. In exchange, the startup takes a 50% cut of the rent. So far, Rent the Backyard has 10 signed letters of intent from homeowners, with more than 1,200 people on its waitlist.

Many homeowners simply can’t afford the upfront cost of building these small units, explains Rent The Backyard co-founder Brian Bakerman. By providing the financing, Rent the Backyard can unlock new income and make homeownership more affordable. At the same time, it can also help renters by creating more apartments. Rent The Backyard and Node, featured below, are a pair of much-needed creative solutions to the housing crisis. More on Rent the Backyard here. 

demoday node


Node wants to use an Ikea-like assembly process to build sustainable backyard cottages — a market the founders say is worth $100 billion and growing quickly. In the past year 25 cities have passed legislation to allow these buildings. Node ships a flat pack of materials that it says only take a few days to assemble into a turnkey backyard cottage or sustainable vacation home. They’ve sold 11 homes in the past two weeks, and the founders are optimistic that they could reach 50% margins with their tech. Early target markets include Seattle, Portland and Vancouver.

As mentioned, both Rent the Backyard and Node are tech-enabled solutions to the housing crises that plague big cities like San Francisco. Node is currently only available in Seattle, Portland and Vancover, but with a little help from VCs, the startup should be able to scale beyond and establish easy-to-build structures across the U.S.




After adding one line of code with Courier, developers can, first, send messages through every communication channel to users. Courier then measures users’ response rates on each channel (Slack, WhatsApp, Facebook Messenger etc.) and determines where notifications should be directed.

Ninety percent of people who say “email is broken” probably just spent the last hour unsubscribing from newsletters and spam. Brand communication has so many distinct avenues but email has always seemed to be the safest, Courier finds the most effective notification channel for a given user (be it email, SMS, Slack, WhatsApp, or any of myriad other options) and then routes all of your messaging that way. This user data can then help other customers of their’s find out how to reach you best.

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Juno College of Technology

JCT is creating the technical university of the future. The startup operates a coding bootcamp, expected to do $3 million in revenue by the end of 2019. Similar to Lamda School, they offer income-share agreements, but “the similarities stops there,” explained the founder. Juno says it places 87% of students who complete their nine-week long program.

Few startups have the acolytes that Lambda School does, Juno is following the company with an income-share agreement that pays the startup back in a percent of your salary, but it’s doing so on a tighter time frame for more basic skills focused on front-end web development. The courses may be keeping students from the upper echelons of software engineering jobs that Lambda School may open up, but the shorter time commitment and dedicated career placement team can help people get into positions they might not have otherwise.


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Billing itself as the Robinhood for India, this startup is allowing users to trade U.S. stocks from India for ₹0 commission. As it is now, Indians don’t have Social Security numbers, preventing them to trade U.S. stocks. GreenTiger provides commission-free trades on NASDAQ and NYSE, and allows users to start trading in two minutes. GreenTiger provides fractional shares, allowing Indian traders to start trading with as little as ₹100. These ex-Microsoft founders describe the opportunity as worth $7.2 billion.

For what GreenTiger lacks in UI originality (that interface seems like a pretty clear Robinhood copy), they make up for in platform reach. Taking on the Indian market with fractional shares could potentially enable people there to gain access to global markets and become more literate on financial matters.

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This is a construction startup that automates workflows and manages bids from subcontractors. To date, Basis has four signed contracts within three weeks of operating. The big vision is to become a full-fledged platform for the construction industry.

What do you get when you combine a former Uber employee with a fast-growing buzzworthy industry? A venture-funded startup. In all seriousness, Basis, led by a former employee of Uber’s Advanced Technologies Group, brings a much-needed tech infusion to an antiquated market worth billions. Funding in U.S.-based construction tech companies hit $3.1 billion last year, a huge jump from $731 million. Funding in the sector is expected to grow significantly in 2019, putting Basis on the fast-track to market domination.

demoday Epic Aerospace

Epic Aerospace

Epic is manufacturing inexpensive space tugs to deliver satellites into geostationary orbit. The 21-year-old founder has been building rockets since he was 16, and is now managing a team of seven aerospace engineers with Epic Aerospace.

The founder describes propulsion as one of the biggest problems for satellite companies, in that it can take up to two years to qualify new satellite systems and can cost up to $30 million. The problem they’re solving is moving satellites from low Earth orbit directly into geostationary orbit. Epic’s tug is half the cost of the competition and is reusable. They’re currently working with Satellogic, and chasing what the founder says is a $3.1 billion geostationary insertion market.