Breaking $10.5M SEED — Stilta raises round led by Andreessen Horowitz /// 180M patents, 250M papers, 1T+ web pages searched per query /// 868 prior-art references found in ~30 minutes /// YC W26 · Stockholm · founded Dec 2025 /// Customers include Roche, Maersk, Alfa Laval /// Breaking $10.5M SEED — Stilta raises round led by Andreessen Horowitz /// 180M patents, 250M papers, 1T+ web pages searched per query /// 868 prior-art references found in ~30 minutes /// YC W26 · Stockholm · founded Dec 2025 /// Customers include Roche, Maersk, Alfa Laval ///
Company Legal Tech · Agentic AI · YC W26

Stilta Taught AI to Read 180 Million Patents So Lawyers Don't Have To

A four-person Stockholm team left McKinsey to point networks of AI agents at the slowest, most document-heavy corner of law. Then a16z and Y Combinator handed them $10.5 million to keep going.

Put a patent number into Stilta's software, add whatever context you have, and step back. Within about half an hour, in one demonstration, the platform surfaced 868 prior-art references against a single wireless-networking patent. A human research team would have stopped somewhere around reference number forty, not because the rest didn't exist, but because reading them was never worth the cost. Stilta's bet is that the cost just changed.

Stilta is a Stockholm company, part of Y Combinator's Winter 2026 batch, building what it calls agentic AI for high-stakes patent work. The pitch is narrow on purpose: run invalidity, infringement, and freedom-to-operate analyses in minutes, across patents, scientific literature, and archived web pages, and return something a lawyer can actually defend - a claim chart with citations, not a confident paragraph. In May 2026, a few months after launching, the company raised a $10.5 million seed round led by Andreessen Horowitz, with Y Combinator and operators from OpenAI, Legora, Lovable, Sana, and Listen Labs joining in.

$10.5M
Seed round, May 2026
180M
Patents indexed
~3x
Recall vs. general AI
4
Founders, ex-McKinsey

01 / THE PROBLEMThe forgotten filing cabinet

Patent work has a peculiar economics problem. Every large company owns patents - sometimes thousands of them - and most of those patents sit untouched. As Stilta CEO Oskar Block puts it, many are "never enforced, never licensed, never even analyzed properly because the cost of doing so was prohibitive." The analysis that would tell you whether a patent is worth defending, whether a competitor is infringing it, or whether it could be licensed for revenue, has historically required specialist lawyers reading documents by hand and billing by the hour.

That makes the analysis expensive, which makes companies do less of it, which means value sits latent in portfolios nobody has the budget to examine. The bottleneck isn't legal judgment. It's reading.

"The question isn't really whether the legal system is prepared for AI. It's whether companies are prepared for what becomes possible when the analytical bottleneck disappears." Oskar Block, CEO & Co-Founder

02 / THE PRODUCTA room full of specialists, in software

Here is how it works in practice. A user enters a patent and the relevant context. From there, a network of AI agents fans out - searching for patents that might conflict with the claim, flagging similar intellectual property, pulling the filing and court history of the patent in question. The agents work in parallel and converge on an answer.

1

Input

Enter a patent number plus any product docs, prior art, or context.

2

Agents fan out

Parallel agents search patents, literature, and web archives at once.

3

Converge

Findings are reconciled the way a panel of specialists would.

4

Claim chart

Output is a color-coded chart with pinpointed, source-backed citations.

Block describes the agents this way: "They reason in parallel and converge the way a room full of specialists would, but at a scale no human team can match." The product ships three core analyses - invalidity, infringement, and freedom-to-operate - plus portfolio analysis that surfaces licensing opportunities across patents a company already owns.

What Stilta searches on every query
Patents~180M
Scientific publications~250M
Archived web pages (Internet Archive)1T+
The corpus is the moat. Bars are scaled for legibility, not to exact proportion - a trillion web pages would otherwise dwarf everything. Source: Stilta.

03 / THE DIFFERENCEBuilt for the auditor, not the applause

Plenty of people have typed a patent question into ChatGPT. The problem in legal work is that a plausible answer is worthless if you can't trace it to a source and take it to court. Stilta's design centers on that constraint: every output is meant to be auditable, tied back to specific evidence, and the practitioner stays in control rather than handing decisions to an autonomous system. The company reports internal benchmarks showing roughly three times better recall than general-purpose models like ChatGPT, Claude, and Perplexity on prior-art search.

Prior-art recall — internal benchmark
3x
Stilta
1x
ChatGPT
1x
Claude
1x
Perplexity
Relative recall on prior-art search, per Stilta's own testing. Benchmarks are self-reported and approximate. Source: Stilta.

The company is sometimes described as "Cursor for patent practitioners" - a reference to the AI coding tool that assists rather than replaces. Its named competitors in the emerging agentic-patent space include Patlytics, Solve Intelligence, and DeepIP. The broader alternative is the status quo: traditional patent databases and manual review inside law firms.

"Patent litigation runs on labor-intensive workflows that haven't meaningfully changed in decades." David Haber, Andreessen Horowitz

04 / THE TEAMFrom consulting to the courtroom's back office

Stilta was founded in December 2025 by four engineers who met in and around McKinsey and its AI arm, QuantumBlack. Oskar Block, the CEO, previously worked at McKinsey, Goldman Sachs, and Swedish unicorns, and had already founded two companies, bootstrapping one past $1M in revenue. Oscar Adamsson, Chief Product Officer, advised more than 50 CEOs at McKinsey and is a competitive mathematician. Petrus Werner, the CTO, built and deployed AI systems at QuantumBlack and Amazon Web Services. Tobias Estreen, a second-time founder with a physics and machine-learning background, led agentic AI teams at QuantumBlack.

The through-line is enterprise deployment in security-reviewed environments, which shows up in how Stilta sells: per-tenant isolation by default, no training on customer data, and a customer's choice of US or EU data residency. For IP work, where the material is often privileged, that posture is part of the product.

Founded
December 2025
HQ
Stockholm, Sweden
Batch
Y Combinator W26
Seed lead
Andreessen Horowitz

05 / THE MARKETWho's actually buying

Stilta's customers split into two groups: in-house IP and legal teams at large enterprises, and the IP law firms that serve them. Cited customers and pilots include Roche, Maersk, Alfa Laval, and the robotics maker KUKA, alongside three of the world's five largest IP firms. By the company's own breakdown, roughly two-thirds of customers are corporate in-house teams and one-third are law firms, split evenly between the United States and Europe.

The business model is straightforward B2B SaaS - software sold into legal departments and firms - though Stilta has not disclosed pricing or revenue. What it has disclosed is a thesis: when the cost of analysis collapses, companies will run analyses they never could before, and some of those forgotten patents will turn out to be worth defending.

Companies hold patents "never enforced, never licensed, never even analyzed properly because the cost of doing so was prohibitive." Oskar Block, on the value hiding in existing portfolios

Whether Stilta becomes the default tool for patent teams or one of several in a crowding field is still an open question - the company is only months old. But the shape of the wager is clear enough. Reading was the bottleneck. Stilta made reading cheap. The interesting part is what people do once the bottleneck is gone.

#patent-intelligence #agentic-ai #legal-tech #prior-art #yc-w26 #a16z #stockholm #saas #intellectual-property