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ps-fuzz

Prompt fuzzing tool for LLM security testing

open sourceupdated Aug 16, 2026

ps-fuzz by Prompt Security is a security testing tool with 680+ GitHub stars that fuzzes system prompts against dynamic LLM-based attack scenarios including jailbreaks, prompt injection, and data extraction attempts. It helps developers harden their GenAI applications by simulating adversarial attacks in a controlled environment, turning LLM security into a testable and reproducible quality gate.

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ps-fuzz automates the security testing of GenAI applications by subjecting system prompts to a comprehensive suite of attack simulations. The tool generates dynamic adversarial inputs covering jailbreak attempts, prompt injection techniques, data extraction attacks, and system prompt leakage scenarios. Each test produces a detailed report showing which attacks succeeded and which defenses held, giving developers concrete guidance on where to strengthen their prompt engineering.

The testing approach treats prompt security like traditional fuzzing: systematically exploring edge cases and attack surfaces that manual testing would miss. Teams can integrate ps-fuzz into CI/CD pipelines to run prompt security regression tests whenever system prompts are modified, catching regressions before they reach production. This transforms LLM security from an ad-hoc concern into a structured, automated quality gate.

With 680+ GitHub stars and project activity into 2026, ps-fuzz addresses the growing need for practical LLM security testing tools. As organizations deploy more AI-powered features, the attack surface for prompt injection and related vulnerabilities expands rapidly. The tool is developed by Prompt Security, a company focused on GenAI security, and serves both security researchers and application developers building with LLMs.

Pricing

Free and open-source

Platforms

Python CLI, CI/CD pipelines

Categories

Tags

Use Cases

PromptLayer logo

PromptLayer

Prompt registry, observability, and evaluation workflows for LLM applications.

PromptLayer is a prompt management, observability, and evaluation platform for LLM applications. Teams use its Prompt Registry, visual editor, request logs, Tables, evaluations, Tool Registry, and Skill Collections to version prompts, replay requests, compare variants, run datasets, and ship prompt changes without redeploying code. Pricing starts with Free $0 for 5 users and 2.5K requests/month, Pro $49/month, Team $500/month, and Enterprise custom.

freemium
Guardrails AI logo

Guardrails AI

Validate and structure LLM outputs with composable Guards

Guardrails AI is an open-source Python and JavaScript framework for validating and structuring LLM outputs using composable Guards built from a Hub of pre-built validators. It handles structured data extraction with Pydantic models, content safety checks including toxicity, PII detection, competitor mentions, and bias filtering, plus automatic re-prompting when validation fails. The Guardrails Hub offers dozens of validators from regex matching to hallucination detection via LLM judges.

free
NVIDIA logo

NeMo Guardrails

Programmable safety rails for LLM applications

NeMo Guardrails is NVIDIA's open-source toolkit for adding programmable safety rails to LLM applications. It supports five guardrail types — input, dialog, retrieval, execution, and output rails — covering content safety, jailbreak detection, topic control, PII masking, hallucination detection, and fact-checking. The toolkit uses Colang, a domain-specific language for defining conversational constraints, and integrates with OpenAI, Azure, Anthropic, HuggingFace, and LangChain/LangGraph.

free

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Used in Stacks

Comparisons

ps-fuzz vs Garak vs NeMo Guardrails — Prompt Injection Testing & LLM Security Tools Compared

As LLM-powered applications become production staples, prompt injection and jailbreak attacks represent some of the most dangerous threat vectors. Developers need tools that can systematically test their systems against these attacks before deployment. This comparison examines three distinct approaches to LLM security: ps-fuzz for targeted prompt fuzzing, Garak for comprehensive vulnerability scanning, and NeMo Guardrails for runtime protection and enforcement.

FAQ

What is ps-fuzz?

ps-fuzz by Prompt Security is a security testing tool with 680+ GitHub stars that fuzzes system prompts against dynamic LLM-based attack scenarios including jailbreaks, prompt injection, and data extraction attempts. It helps developers harden their GenAI applications by simulating adversarial attacks in a controlled environment, turning LLM security into a testable and reproducible quality gate.

Is ps-fuzz free?

Yes — ps-fuzz is open source and free to use. Free and open-source

Is ps-fuzz open source?

Yes — ps-fuzz is open source.

What are the best ps-fuzz alternatives?

The top editor-verified ps-fuzz alternatives are PromptLayer, Guardrails AI, NeMo Guardrails.

How does ps-fuzz score in our review?

Our hands-on review scores ps-fuzz 72/100 overall, based on speed, privacy, and developer-experience testing.