Trylon Gateway: The Open Source Firewall for LLMs

Building production-grade LLM applications means managing risks: prompt injections, toxic responses, data leaks, and inconsistent behavior. Trylon Gateway is an open-source AI Gateway that provides the essential guardrails to manage these risks, ensuring your AI applications are secure, reliable, and responsible.

It acts as a high-performance, self-hosted proxy that sits between your application and models from OpenAI, Google Gemini, and Anthropic Claude, giving you complete control over every interaction.

How It Works

Trylon intercepts API calls to and from LLMs. It applies your custom policies locally to validate, sanitize, or block requests and responses in real-time, all within the security of your own infrastructure.

Why Choose Trylon Gateway?

• Defend Against Attacks: Implement a critical defense layer against common vulnerabilities like prompt injections, insecure outputs, and data exfiltration.
• Ensure Data Privacy & Compliance: Automatically find and redact PII (Personally Identifiable Information) before it leaves your network, helping you build compliant applications.
• Enforce Brand Safety: Use the powerful policy engine to implement content filtering, blocking toxicity, profanity, and other undesirable language to protect your users and your brand.
• Unify Your AI Stack: Act as a single LLM firewall and proxy for multiple providers. Swap models without changing your application's core safety logic.
• High-Performance & Self-Hosted: Built with FastAPI, Trylon Gateway is fast. Running in your own infrastructure means you have complete control and data privacy.

Use Cases

• Public-facing Chatbots: Prevent users from submitting sensitive data and ensure the LLM does not respond with toxic or off-brand content.
• Internal AI Tools: Protect against the accidental leakage of internal secrets, API keys, or project codenames in prompts or responses.
• Regulated Industries (Healthcare, Finance): Build a foundational layer for HIPAA or GDPR compliance by implementing strong PII redaction and logging policies.
• Content Generation Platforms: Ensure that AI-generated content adheres to community guidelines and safety standards.

Quick Start

The fastest way to deploy your own AI Gateway.

Prerequisites: Docker and Docker Compose.

1. Clone the repository:

   git clone https://github.com/trylonai/gateway.git
   cd gateway
   

2. Prepare your environment:

   # Copy the example environment file. No edits are needed to run the quick start.
   cp .env.example .env
   
   # An example policies.yaml and docker-compose.yml are already present.
   

3. Launch the Gateway:

   docker-compose up -d
   

   Note: The first launch will take several minutes. The gateway needs to download the machine learning models (~1.5GB+). Subsequent launches will be much faster because the models are stored in a persistent Docker volume (trylon_hf_cache).

   You can monitor the download progress and see when the application is ready by watching the logs:

   docker-compose logs -f
   

4. Test a Guardrail in Action

   The default policies.yaml comes with a PII guardrail enabled to block any request containing an email address. Let's test it.

   curl -s -X POST "http://localhost:8000/v1/chat/completions" \
     -H "Authorization: Bearer $OPENAI_API_KEY" \
     -H "Content-Type: application/json" \
     -d '{
       "model": "gpt-3.5-turbo",
       "messages": [{"role": "user", "content": "My email address is [email protected]"}]
     }' | jq
   

   You'll see a response with finish_reason: "content_filter", confirming the block. Congratulations! You've just seen a guardrail in action without writing any code.

API Usage & Examples

For detailed, runnable examples, please see the /examples directory.

1. OpenAI Proxy (POST /v1/chat/completions)

Configure your OpenAI client to point to the Trylon Gateway.

import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ.get("OPENAI_API_KEY"), # Your REAL OpenAI key
    base_url="http://localhost:8000/v1"      # Your Trylon Gateway URL + /v1
)

Pro-Tip: To reliably detect blocks, use client.with_raw_response to inspect the X-Trylon-Blocked: true header or check for finish_reason: "content_filter".

2. Gemini & Claude Proxies

Trylon offers the same drop-in proxy capability for Google Gemini and Anthropic Claude.

import google.generativeai as genai
genai.configure(
    api_key=os.environ.get("GEMINI_API_KEY"),
    client_options={"api_endpoint": "http://localhost:8000"},
    transport='rest'
)

from anthropic import Anthropic
client = Anthropic(
    api_key=os.environ.get("ANTHROPIC_API_KEY"),
    base_url="http://localhost:8000/anthropic"
)

3. Direct Validation (POST /safeguard)

For custom workflows, use the /safeguard endpoint to validate content without proxying.

curl -s -X POST "http://localhost:8000/safeguard" \
  -H "Content-Type: application/json" \
  -d '{
    "messages": [
      {"role": "user", "content": "My email is [email protected]."}
    ]
  }' | jq

Response:

{
  "safety_code": 10,
  "message": "Potentially sensitive information detected.",
  "action": 0
}

Policy Configuration (policies.yaml)

This file is the heart of your AI Gateway. All rules are defined here. See the full Policy Configuration Guide for detailed mappings and advanced examples.

Contributing

We are building a community dedicated to making AI safer and more reliable. Contributions are welcome!

• Check out the open issues to see where you can help.
• Read our CONTRIBUTING.md guide to get started.
• Have an idea for a new guardrail? Open a feature request!

Relationship to Trylon AI Cloud

This open-source project is the core data plane that powers the Trylon AI commercial platform. Our cloud offering builds on this core to provide an enterprise-ready solution with: a UI for policy management, centralized observability, team collaboration (RBAC/SSO), and managed API key security.