How Andrew Antos Grew Within to $20M ARR in 18 Months, Then Sold His $10M Business to Bet On It

TL;DR: Within is an enterprise AI company that builds what its customers call a "company brain" — a map of how work actually gets done inside a large organization, used to decide where AI agents should go and to give those agents company-specific context. It is the rebranded version of Klarity, founded in 2017 by Andrew Antos (CEO), a former M&A attorney from Europe, and Nischal Nadhamuni (CTO), who met in an entrepreneurship class at MIT. Public trackers put total funding at roughly $90–92 million as of September 2026, including a $70 million Series B, with backers including Nat Friedman, Daniel Gross, Scale Venture Partners and Tola Capital. Customers include OpenAI, DoorDash, ServiceNow, Salesforce, JLL and McKesson. The remarkable part of the story: the product started as a throwaway internal widget, hit $350K ARR in five weeks, grew to roughly $20 million ARR in about 18 months, and Antos then sold off the roughly $10 million business he had spent years building to go all in on it. He told the whole story on The Product Market Fit Show.

What does Within do?

Within sits underneath a company's AI strategy rather than on top of it.

Big enterprises want to deploy AI agents. The blocker is that nobody has written down how the work actually happens — and the real process is almost never the documented one.

"These complicated business processes in enterprise run on exceptions. You have one happy path and that applies to twenty percent of things and then eighty percent is an exception of some kind." — Andrew Antos, Within

The original version of the product took a Zoom recording of someone doing their job and turned it into a full business requirements document — screenshots, steps, exceptions and all — in minutes instead of the hours a forward-deployed engineer would spend writing it up. That grew into a system that observes work at scale and produces a structured map of it.

Antos is careful to distinguish this from documentation software:

"The way we think about it is more like we're a context layer or a company brain. It's a new data plane, how work gets done, how people make decisions, how they get approvals, how long things take, and do that at scale through observation. Rather than building SOPs to help people onboard." — Andrew Antos, Within

Once the map exists, the customer can find the automatable work, quantify what it is worth, and build the agents. As Antos put it on the show, customers are now "building these dream teams of people and agents with it."

Key stat: DoorDash mapped more than 3,800 processes in 14 weeks using Within, per the company's 2026 reporting.

Who founded Within?

Within was founded by Andrew Antos and Nischal Nadhamuni in 2017.

Antos is originally from Europe and had exactly one job before starting the company: corporate M&A attorney. He came to the US for grad school, cross-registered for a startup course at MIT, and met Nadhamuni there.

"We walked around Cambridge for three hours after that and we both had this feeling that AI is happening, and it's happening without us." — Andrew Antos, Within

The signal that convinced them in 2017 was not a product or a benchmark. It was student behavior.

"Professors would have sign-ups for machine learning courses at 07:00am or 07:30am in the morning and there would be students in sleeping bags sleeping overnight." — Andrew Antos, Within

That turned into a durable heuristic he still uses for finding markets early:

"Look at what people on the fringes are doing. Because oftentimes what starts as a fringe activity or as a fringe interest then becomes mainstream." — Andrew Antos, Within

How much has Within raised?

• Total funding: roughly $90–92 million, per public funding trackers as of September 2026.
• That total includes a $70 million Series B.
• Investors include Nat Friedman, Daniel Gross, Scale Venture Partners and Tola Capital. The company is also listed in the Y Combinator company directory.
• Customers named publicly include OpenAI, DoorDash, ServiceNow, Salesforce, JLL and McKesson, plus several of the largest private equity funds by AUM.

Note that the "Within" name is new. The company operated as Klarity for most of its life, and the rebrand landed the day before this episode was recorded — which is why most historical funding coverage is filed under Klarity.

The three separate times Within found product market fit

Antos has now been through the search three times in one company. Each attempt was faster than the last, and the gap between them is the most useful data in the story.

Attempt one: AI contract review for lawyers (2017–2020). The first product was an NDA review tool with no application at all — a customer forwarded an NDA to a dedicated email address and got a marked-up version back in three to fifteen minutes. It signed real logos, including Salesforce. It did not generalize.

"We started with law firms and made zero progress." — Andrew Antos, Within

Moving to in-house legal teams helped, because they were not billing by the hour. It still capped out.

"It was basically a lifestyle business, right? It just didn't grow fast enough because the problem is not big enough for a sufficient number of people and so that naturally caps your growth." — Andrew Antos, Within

Key stat: after two and a half years on the legal product, the company was at roughly $800K ARR — Antos's own number on the show.

Attempt two: document AI for finance teams (2020–2024). Rather than pick an industry, they sliced the market by function, on the logic that they had no unfair advantage in any particular vertical. Finance teams read the same documents lawyers do — contracts, POs, invoices, expense receipts — and there are far more of them. The team gave itself three months to build and a hard number to hit.

They set the bar at $250K ARR from a minimum of eight customers in six months, and hit roughly $340K from eight customers. That business — Antos describes it as "a mini Palantir for complex financial workflows" — grew 2x to 2.5x a year to about $10 million ARR.

Attempt three: the side widget (2024–today). At the company's own conference, roughly 500 people, they launched a year's worth of sophisticated new product plus one small internal tool on the side.

"Everybody's like, OK, this is cool. But everybody wants to talk about that one little thing that we launched on the side." — Andrew Antos, Within

It was not even a product. It was a widget. People started asking how to buy it anyway, and the first twelve to fourteen deals each had a different pricing model because pricing was being invented live in the conversations.

Key stat: the new product did ~$350K ARR in five weeks and over $1 million the following quarter — the same revenue that took six months on the previous product, and about a year on the one before that.

Antos's framing of why they moved: it was not only the growth rate. It was that the old business ran on professional services and delivery, and they were bad at it.

"We were trying to crack that problem every single day for a couple of years, and we were just really struggling with it. We were not good at it." — Andrew Antos, Within

Why he sold a $10M business instead of running both

The new product overtook a roughly $10 million ARR business in about a year. Running both was the obvious answer, and it is the wrong one for a company that wants to grow fast.

The decision rule Antos used was not financial:

"You always need to optimize for the customer. Because the customer keeps your business alive, and then you optimize for the team. Because the team supports the customer." — Andrew Antos, Within

A professional services firm that had already been supporting some of the implementations for years asked to take the business over. It bought the product line and hired every person supporting it, so customers kept the same product and the same people, and Within pointed the entire company at the new business. Antos estimates that new business went from roughly zero to about $20 million ARR in a year and a half.

The 30 and 100 rule

The most portable idea in the episode is Antos's pair of numbers.

"You want to talk to roughly thirty people to validate an idea or invalidate an idea. Ten is not enough because you can always find Ten friendlies or ten unfriendlies. Fifty or a hundred is to difficult, too many." — Andrew Antos, Within

And on the other end:

"You truly find the core of the product market fit once you sell a hundred customers. It doesn't mean everybody's super happy and everybody's at a huge deal size but around a hundred. You actually have a hundred goes at it and then the motion kind of reveals itself." — Andrew Antos, Within

Thirty conversations to decide whether to build. One hundred closed customers before you believe the shape of the fit.

Key lessons from Andrew Antos's playbook

1. Nine out of ten things fail, and the incremental ones are the failures. Antos's mental model inverted over ten years: he now assumes most bets don't work, and that a bet which "kind of works" is a bet that didn't. The one in ten "works so well that it carries everything else." 2. You cannot increment your way out of slow growth. Optimizing a demo-to-close rate from 40% to 50% is real. Going from 10% to 50% is a market problem, not a go-to-market problem. 3. Set the kill metric before you run the experiment. Four to five hypotheses per quarter, ninety-day cycles, one owner and one number each. For the MCP connector the bar was 100 qualifying users in 90 days. 4. Build the listening system, not just the recordings. Within pipes every customer conversation into Salesforce, enriches it with product usage and support tickets into a "Customer 360" database, and runs agents over it that report daily to each team. Crucially, the opinions are weighted: existing customers count most, a single first meeting that goes nowhere counts least. 5. Ship in the customer's words, not yours. The team debated calling the product an "intelligence layer." Customers called it a company brain, so that is what it is called now. 6. One channel that works beats ten that are fine. Within runs zero Google ads and puts most of its marketing budget into events — including renting a Palo Alto storefront for a month as a pop-up data art gallery built from its State of Agentic Work survey.

For more on enterprise AI companies scaling through this same window, see Tessl and spec-driven development, Model ML's $75M Series A and Augment's AI teammate for logistics.

FAQ: Within

Q: What is Within? A: Within is an enterprise AI company that maps how work actually gets done inside a large organization into a structured "company brain," then uses that context to find automation opportunities and run AI agents alongside employees. It was previously called Klarity.

Q: Who is the CEO of Within? A: Andrew Antos, who co-founded the company in 2017 with CTO Nischal Nadhamuni. Antos was a corporate M&A attorney before starting the company; the two met in an entrepreneurship class at MIT.

Q: Is Within the same company as Klarity? A: Yes. Klarity rebranded to Within in 2026 to reflect its move beyond finance-team document automation into enterprise-wide AI transformation. Older funding and press coverage is filed under the Klarity name.

Q: How much funding has Within raised? A: Roughly $90–92 million in total as of September 2026 according to public funding trackers, including a $70 million Series B. Investors include Nat Friedman, Daniel Gross, Scale Venture Partners and Tola Capital.

Q: Who are Within's customers? A: Publicly named customers include OpenAI, DoorDash, ServiceNow, Salesforce, JLL and McKesson, along with several of the largest private equity funds by assets under management. DoorDash mapped more than 3,800 processes in 14 weeks on the platform.

Q: How fast did Within grow? A: On the show, Antos said the product did about $350K ARR in its first five weeks and over $1 million the next quarter, reaching roughly $20 million ARR in about a year and a half.

Sources: Listen to the Full Founder Story

• Andrew Antos, Co-Founder & CEO of Within — found product market fit three separate times in one company, then sold the $10M business he had built to focus entirely on the third one.

Listen to the full interview: He sold his 8-figure business to bet on a side app — then grew it 20x in a year.

Listen to the full episode at pmf.show for the complete story.

Last updated: September 2026