Silmaril YC Application

Spring 2026Active

Silmaril went through Y Combinator in the Spring 2026 batch as a B2B company. Below: what the company does, who founded it, and its application to YC, reconstructed question by question in the real YC form.

YC batch: Spring 2026
Industry: B2B
Team size: 2
Status: Active
Launched: 2026

Founders

Aum UpadhyayFounder
Eduardo VelascoFounder

What Silmaril does

Silmaril is self-healing prompt injection defense for AI native applications and agents. It understands application context to block 2x as many threats as current SOTA defenses with 10x lower latency. Customers plug us into agentic frameworks like LangGraph with 5 lines of code. Silmaril has stopped $28M of damages for customers.

Silmaril's YC application, reconstructed

Y Combinator application

Silmaril, Spring 2026 batch. The real form questions, answered from public data.

Founders2
Company7
Progress7
Idea4
Equity3
Curious2
Batch Preference1

Company

Company name

Silmaril

Describe what your company does in 50 characters or less.

Self-healing prompt injection defense

What is your company going to make? Please describe your product and what it does or will do.

We're building Silmaril, a defense system for AI native apps and agents that automatically detects and blocks prompt injection attacks. It uses knowledge of the app's context to prevent more threats than current defences and does so with lower latency. Customers connect it to frameworks like LangGraph using just a few lines of code.

Where do you live now, and where would the company be based after YC?

We live in San Francisco, CA, and plan to keep the company here after YC.

Explain your decision regarding location.

We choose to base in San Francisco to stay close to our customers, partners, and the AI startup ecosystem driving demand for prompt injection defense.

21 more answers in the full application

Founders, Progress, Idea, Equity, Curious, Batch Preference are in the full version. Create a free account to open it in YC Insights, next to every other YC batch.

See full application

Frequently Asked Questions

Is this the real Silmaril YC application?

No. Y Combinator keeps submitted applications private. This is a reconstruction: the real YC form questions, answered from Silmaril's public data (launch notes, founder backgrounds, product description). It shows how a company like Silmaril would present itself to YC, not the text they submitted.