YC Spring 2026 (P26) company

Silmaril

Runtime security for AI that self-improves

b2bindustrial4 public signals

About Silmaril

Silmaril is the first runtime security for AI that self-improves. 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.

Public traction evidence

Each signal links to the public source used for attribution.

  1. X

    Garry Tan post about Silmaril prompt injection defense

    Garry Tan wrote that Silmaril (misspelled Simaril) YC Spring 2026 is SOTA prompt injection defense for LLMs.

  2. X

    Garry Tan reply about using Silmaril

    Garry Tan replied that he uses Silmaril for shell-level prompt injection and infiltration blocking.

  3. LinkedIn

    Grey Baker post about Silmaril

    Grey Baker highlighted Silmaril and its work on prompt-injection defense.

  4. YouTube

    Silmaril: The world's first self-healing prompt injection defense

    Learn about the firewall and book a call: silmaril.dev