Top 5 LLM Gateways in 2025: The Complete Guide to Choosing the Best AI Gateway

Yusuf Ishola· June 16, 2025

Running multiple LLMs in production is complex. You need to manage different API formats, handle provider outages, optimize costs, and monitor performance—all while keeping latency low.

Fortunately, LLM Gateways (or LLM routers) can help solve these problems, acting as intelligent gateways between your application and AI providers and becoming a must-have for anyone building production-scale AI applications.

This guide evaluates the top 5 LLM Gateways available today, with a focus on real-world utility and production readiness.

Let's dive in!

TL;DR

Here's a quick overview of the top 5 LLM Gateways:

Table of Contents

• Why You Need an LLM Gateway
• How to Choose the Best LLM Router
• Top 5 LLM Gateways: In-Depth Comparison
• 1.Helicone AI Gateway
• 2. OpenRouter
• 3. Portkey
• 4. LiteLLM
• 5. Unify AI
• Which LLM Router is Best for You?
• Conclusion

Why You Need an LLM Gateway

Integrating LLMs via direct API calls seems simple until you hit production and start to scale. Here are some things that could go wrong:

• Provider Lock-in: Your codebase becomes tightly coupled to a given provider's API format. Switching to a different provider means rewriting everything.

• No Redundancy: When your provider goes down (and they all do), your application goes down with it.

• Cost Blindness: You discover your AI spend only when the monthly bill arrives. By then, it's too late.

• Performance Guesswork: You don't know which provider is fastest for your use case, or how to optimize routing.

LLM routers abstract these complexities behind a unified interface while adding intelligent routing, automatic failovers, and real-time observability.

How to Choose the Best LLM Router

Here are five key things to consider when selecting the best LLM router:

• Core Functionality: How well does it route requests, unify APIs, and handle deployments?
• Optimization: What cost-saving features, caching mechanisms, and performance tools does it offer?
• Integration: How easy is setup? What frameworks are supported? How customizable is it?
• Reliability: Does it provide monitoring, load-balancing, and failover capabilities?
• Scalability: How easy is it to scale as your application grows?

Top 5 LLM Gateways: In-Depth Comparison

Scroll to see the full table —>

Let's now take a look at each router in detail.

1.Helicone AI Gateway

The Helicone AI Gateway is one of the few LLM routers written in the highly performant Rust programming language.

It provides ultra-fast performance (e.g., 8ms P50 latency) and is horizontally scalable. It also features a single binary deployment, making it simple to run on AWS, GCP, Azure, on-prem, Kubernetes, Docker, or bare metal.

It also integrates seamlessly with Helicone's observability tools, providing real-time insights into provider performance and usage patterns.

Standout Features

• Speed: Built with Rust making it lightweight and super fast.
• Latency + PeakEWMA Load-Balancing: Tracks real-time latency and load across providers using moving averages. Routes to the fastest available provider for up to 40% latency reduction.
• Built-in Observability: Native cost tracking, latency metrics, and error monitoring with Helicone's LLM Observability tools and OpenTelemetry integrations. Real-time dashboards show provider performance and usage patterns.
• Intelligent Caching: Redis-based caching with configurable TTL reduces costs by up to 95%. Cross-provider compatibility—cache OpenAI responses, serve for Anthropic requests.
• Multi-Level Rate Limiting: Granular controls across users, teams, providers, and global limits. Distributed enforcement prevents quota overruns in multi-instance deployments.
• Health-Aware Routing: Automatic provider health monitoring with circuit breaking. Removes failing providers and tests for recovery without manual intervention.
• Regional Load-Balancing: Routes to nearest provider regions automatically for global applications.

Pros & Cons

Getting Started with Helicone AI Gateway

Here's how to migrate from direct API calls to AI Gateway in minutes:

Run container, adding necessary API keys

docker run -d --name helix \
  -p 8080:8080 \
  -e OPENAI_API_KEY=your_openai_key \
  -e ANTHROPIC_API_KEY=your_anthropic_key \
  helicone/helix:latest

Use any model via the OpenAI SDK

from openai import OpenAI

client = OpenAI(
    base_url="http://localhost:8080/ai",
    api_key="sk--xxxx" # Dummy key, gateway manages auth
)

# Route to any provider through the same interface, we handle the rest.
response = client.chat.completions.create(
    model="anthropic/claude-3-5-sonnet",  # Or openai/gpt-4o, gemini/gemini-2.5-pro, etc.
    messages=[{"role": "user", "content": "Hello from Helix!"}]
)

And that's it!

2. OpenRouter

OpenRouter provides a unified API that gives you access to hundreds of AI models through a single endpoint, while automatically handling fallbacks and selecting the most cost-effective options.

It focuses on providing a simple, user-friendly interface for non-technical users than robust features for production-scale applications.

Standout Features

• User-Friendly Interface: Web UI allows direct interaction without coding
• Extensive Model Support: Access to hundreds of models through a unified API
• Pass-through billing: Centralized billing for all providers
• Automatic Fallbacks: Seamlessly switches providers during outages
• Quick Setup: <5 minutes from signup to first request

Best For: Teams wanting immediate access to multiple LLMs without complex setup, especially when non-technical stakeholders need direct access.

3. Portkey

Portkey's AI Gateway is a comprehensive platform designed to streamline and enhance AI integration for developers and organizations.

Built on top of Portkey—an observability tool, it serves as a unified interface for interacting with over 100 AI models, offering advanced tools for control, visibility, and security in your Generative AI apps.

Standout Features

• Advanced Guardrails: Enforce content policies and output controls

• Virtual Key Management: Secure API key handling for teams

• Configurable Routing: Automatic retries, fallbacks with exponential backoff

• Prompt Management: Built-in tools for prompt versioning and testing

• Enterprise Features: Compliance controls, audit trails, and SSO support

• Observability: Detailed analytics, custom metadata, and alerting

Best For: Development teams needing detailed control over routing behavior and enterprise-grade security features.

4. LiteLLM

LiteLLM is an LLM router that focuses on flexibility, offering a unified interface across 100+ LLM providers with completely free, open-source access.

It excels at advanced routing algorithms and comprehensive team management through highly customizable configurations.

Standout Features

• Advanced Routing Strategies: Latency-based, usage-based, cost-based routing with customizable algorithms
• Comprehensive Load-Balancing: Multiple algorithms including least-busy, latency-based, and usage-based with Kubernetes scaling
• Team Management: Virtual keys, budget controls, tag-based routing, and team-level spend tracking
• Production Features: Pre-call checks, cooldowns for failed deployments, alerting via Slack/email, and 15+ observability integrations

Best For: Engineering teams building production LLM infrastructure who need maximum control, extensive provider support, and advanced routing capabilities.

5. Unify AI

Unify.AI is a highly customizable LLMOps platform that prioritizes simplicity and customization over complexity.

It's designed for developers who want to build custom interfaces for logging, evaluations, guardrails, and other LLM operations without the overhead of advanced features.

Standout Features

• Simple Interface: Clean UI for basic routing needs
• Provider-Level Routing: Route between different AI providers
• Basic Caching: Simple response caching to reduce costs

Best For: Small projects or teams with basic routing needs who only need to switch between providers, not specific models.

Which LLM Router is Best for You?

Conclusion

LLM gateways are becoming essential infrastructure for production AI applications. While all five options solve basic routing needs, they differ significantly in sophistication and capabilities.

Helicone AI Gateway provides a robust set of production-grade features like latency load-balancing and built-in observability. OpenRouter excels at simplicity. Portkey offers enterprise controls. LiteLLM provides open-source flexibility. Unify.AI covers basic needs.

This guide should serve as a good starting point for your decision-making process. Good luck!