Silmaril
A self-healing prompt-injection defense for AI apps and agents. Silmaril's multi-head classifier weighs user intent, app context and execution state to block harmful actions before they happen, integrates into frameworks like LangGraph in about five lines, and retrains continuously as new attacks appear. YC 2026.
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Our take
A self-healing prompt-injection defense for AI apps and agents. Its multi-head classifier weighs user intent, app context and execution state to block harmful actions before they happen, drops into frameworks like LangGraph in about five lines, and retrains continuously. The company reports catching 2x more attacks at 10x lower latency. YC 2026.
Best for
Teams shipping AI agents that need prompt-injection protection without slowing the app down.
Pros
- Context-aware, not just keyword filtering
- ~5 lines to integrate (e.g. LangGraph)
- Retrains continuously against new attacks
- Built for agents, low added latency
Cons
- Very new (founded 2026)
- Headline metrics are vendor-reported
- Security tool needs ongoing trust-building
How it compares
Against static guardrail libraries, Silmaril's pitch is a defense that understands application context and improves itself rather than relying on fixed rules.
Full review
Silmaril is a prompt-injection defense built for AI-native applications and agents. Its multi-head classifier evaluates user intent, application context and execution state together, aiming to catch harmful outcomes before they happen rather than matching known bad strings.
It integrates into agentic frameworks like LangGraph in roughly five lines and retrains continuously as new attack patterns emerge. The founders previously built security frameworks at AWS and Amazon; the company is part of Y Combinator's 2026 batch and reports catching twice as many attacks at a tenth of the latency of leading defenses, though those figures are self-reported.
Cloudkart Trust Graph
3.6/5- Actual Utility4/5
Source: Initial LLM-authored rubric (backfill)
- Ease of Use4/5
Source: Initial LLM-authored rubric (backfill)
- Pricing Fairness3/5
Source: Initial LLM-authored rubric (backfill)
- Reliability3/5
Source: Initial LLM-authored rubric (backfill)
- Differentiation4/5
Source: Initial LLM-authored rubric (backfill)
Scored as of . Each score is versioned and auditable; vendors cannot buy it.
How this score is set
- Editorial rubric
- Primary signal — five dimensions, 3.6/5 average.
- Community reviews
- None yet.
- Pricing verified
- Not yet verified
- Independence
- Score set by our editorial team before any affiliate relationship is considered. No vendor can buy it.
Frequently asked questions
- Is Silmaril free, and how much does it cost?
- Silmaril is a paid tool.
- Who is Silmaril best for?
- Teams shipping AI agents that need prompt-injection protection without slowing the app down.
- How is Silmaril rated on Cloudkart.ai?
- Silmaril scores 3.6 out of 5 on the Cloudkart.ai rubric, which weighs actual utility, ease of use, pricing fairness, reliability and differentiation. Scores are set editorially and can never be bought.
Community reviews
No community reviews yet. Be the first to share how Silmaril works for you.
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